A comprehensive analysis of Trehalose-6-phosphate synthase (TPS) gene for salinity tolerance in chickpea (Cicer arietinum L.)

Soil salinity affects various crop cultivation but legumes are the most sensitive to salinity. Osmotic stress is the first stage of salinity stress caused by excess salts in the soil on plants which adversely affects the growth instantly. The Trehalose-6-phosphate synthase (TPS) genes play a key role in the regulation of abiotic stresses resistance from the high expression of different isoform. Selected genotypes were evaluated to estimate for salt tolerance as well as genetic variability at morphological and molecular level. Allelic variations were identified in some of the selected genotypes for the TPS gene. A comprehensive analysis of the TPS gene from selected genotypes was conducted. Presence of significant genetic variability among the genotypes was found for salinity tolerance. This is the first report of allelic variation of TPS gene from chickpea and results indicates that the SNPs present in these conserved regions may contribute largely to functional distinction. The nucleotide sequence analysis suggests that the TPS gene sequences were found to be conserved among the genotypes. Some selected genotypes were evaluated to estimate for salt tolerance as well as for comparative analysis of physiological, molecular and allelic variability for salt responsive gene Trehalose-6-Phosphate Synthase through sequence similarity. Allelic variations were identified in some selected genotypes for the TPS gene. It is found that Pusa362, Pusa1103, and IG5856 are the most salt-tolerant lines and the results indicates that the identified genotypes can be used as a reliable donor for the chickpea improvement programs for salinity tolerance.

Stomata coordinate with plant hydraulics to regulate transpiration response to vapour pressure deficit in wheat

Genotypic variation in transpiration (Tr) response to vapour pressure deficit (VPD) has been studied in many crop species. There is debate over whether shoots or roots drive these responses. We investigated how stomata coordinate with plant hydraulics to mediate Tr response to VPD and influence leaf water status in wheat (Triticum aestivum L.). We measured Tr and stomatal conductance (gs) responses to VPD in well-watered, water-stressed and de-rooted shoots of eight wheat genotypes. Tr response to VPD was related to stomatal sensitivity to VPD and proportional to gs at low VPD, except in the water-stressed treatment, which induced strong stomatal closure at all VPD levels. Moreover, gs response to VPD was driven by adaxial stomata. A simple linear Tr response to VPD was associated with unresponsive gs to VPD. In contrast, segmented linear Tr to VPD response was mostly a function of gs with the breakpoint depending on the capacity to meet transpirational demand and set by the shoots. However, the magnitude of Tr response to VPD was influenced by roots, soil water content and stomatal sensitivity to VPD. These findings, along with a theoretical model suggest that stomata coordinate with plant hydraulics to regulate Tr response to VPD in wheat.

Alien chromosome segment from Aegilops speltoides and Dasypyrum villosum increases drought tolerance in wheat via profuse and deep root system

BACKGROUND

Recurrent drought associated with climate change is a major constraint to wheat (Triticum aestivum L.) productivity. This study aimed to (i) quantify the effects of addition/substitution/translocation of chromosome segments from wild relatives of wheat on the root, physiological and yield traits of hexaploid wheat under drought, and (ii) understand the mechanism(s) associated with drought tolerance or susceptibility in wheat-alien chromosome lines.

METHODS

A set of 48 wheat-alien chromosome lines (addition/substitution/translocation lines) with Chinese Spring background were used. Seedling root traits were studied on solid agar medium. To understand the influence of drought on the root system of adult plants, these 48 lines were grown in 150-cm columns for 65 d under full irrigation or withholding water for 58 d. To quantify the effect of drought on physiological and yield traits, the 48 lines were grown in pots under full irrigation until anthesis; after that, half of the plants were drought stressed by withholding water for 16 d before recording physiological and yield-associated traits.

RESULTS

The alien chromosome lines exhibited altered root architecture and decreased photochemical efficiency and seed yield and its components under drought. The wheat-alien chromosome lines T5DS·5S#3L (TA5088) with a chromosome segment from Aegilops speltoides (5S) and T5DL.5 V#3S (TA5638) with a chromosome segment from Dasypyrum villosum (5 V) were identified as drought tolerant, and the drought tolerance mechanism was associated with a deep, thin and profuse root system.

CONCLUSIONS

The two germplasm lines (TA5088 and TA5638) could be used in wheat breeding programs to improve drought tolerance in wheat and understand the underlying molecular genetic mechanisms of root architecture and drought tolerance.

GABA (γ-aminobutyric acid), as a thermo-protectant, to improve the reproductive function of heat-stressed mungbean plants

Rising global temperatures are proving to be detrimental for the agriculture. Hence, strategies are needed to induce thermotolerance in food crops to sustain the food production. GABA (γ-aminobutyric acid), a non-protein amino acid, can partially protect plants from high-temperature stress. This study hypothesises that declining GABA concentrations in the cells of heat-stressed mungbean plants increases the heat-sensitivity of reproductive function. Mungbean plants were grown in a natural, outdoor environment (29.3/16.1 ± 1 °C as mean day/night temperature, 1350-1550 µmol m-2 s-1 light intensity, 60-65% as mean relative humidity) until the start of the reproductive stage. Subsequently, two temperature treatments were imposed in a controlled environment-control (35/23 °C) and heat stress (45/28 °C)-at about 800 µmol m-2 s-1 light intensity and 65-70% as mean relative humidity, until pod maturity. In heat-stressed (HS) plants, endogenous GABA concentrations in leaf and anther samples had declined by 49 and 60%, respectively, and to a much lesser degree in the plants, exogenously supplemented with 1 mM GABA. The reproductive function of GABA-treated heat-stressed plants improved significantly in terms of pollen germination, pollen viability, stigma receptivity and ovule viability, compared to untreated HS controls. In addition, GABA-treated heat-stressed plants had less damage to membranes, photosynthetic machinery (chlorophyll concentration, chlorophyll fluorescence, RuBisCO activity were functionally normal) and carbon assimilation (sucrose synthesis and its utilisation) than the untreated HS controls. Leaf water status improved significantly with GABA application, including enhanced accumulation of osmolytes such as proline and trehalose due to increase in the activities of their biosynthetic enzymes. GABA-treated heat-stressed plants produced more pods (28%) and seed weight (27%) plant-1 than the untreated controls. This study is the first to report the involvement of GABA in protecting reproductive function in mungbean under heat stress, as a result of improved leaf turgor, carbon fixation and assimilation processes, through the augmentation of several enzymes related to these physiological processes.

Evolving gene banks: improving diverse populations of crop and exotic germplasm with optimal contribution selection

We simulated pre-breeding in evolving gene banks - populations of exotic and crop types undergoing optimal contribution selection for long-term genetic gain and management of population genetic diversity. The founder population was based on crosses between elite crop varieties and exotic lines of field pea (Pisum sativum) from the primary genepool, and was subjected to 30 cycles of recurrent selection for an economic index composed of four traits with low heritability: black spot resistance, flowering time and stem strength (measured on single plants), and grain yield (measured on whole plots). We compared a small population with low selection pressure, a large population with high selection pressure, and a large population with moderate selection pressure. Single seed descent was compared with S0-derived recurrent selection. Optimal contribution selection achieved higher index and lower population coancestry than truncation selection, which reached a plateau in index improvement after 40 years in the large population with high selection pressure. With optimal contribution selection, index doubled in 38 years in the small population with low selection pressure and 27-28 years in the large population with moderate selection pressure. Single seed descent increased the rate of improvement in index per cycle but also increased cycle time.

Salt tolerance of Beta macrocarpa is associated with efficient osmotic adjustment and increased apoplastic water content

The chenopod Beta macrocarpa Guss (wild Swiss chard) is known for its salt tolerance, but the mechanisms involved are still debated. In order to elucidate the processes involved, we grew wild Swiss chard exposed to three salinity levels (0, 100 and 200 mm NaCl) for 45 days, and determined several physiological parameters at the end of this time. All plants survived despite reductions in growth, photosynthesis and stomatal conductance in plants exposed to salinity (100 and 200 mm NaCl). As expected, the negative effects of salinity were more pronounced at 200 mm than at 100 mm NaCl: (i) leaf apoplastic water content was maintained or increased despite a significant reduction in leaf water potential, revealing the halophytic character of B. macrocarpa; (ii) osmotic adjustment occurred, which presumably enhanced the driving force for water extraction from soil, and avoided toxic build up of Na(+) and Cl(-) in the mesophyll apoplast of leaves. Osmotic adjustment mainly occurred through accumulation of inorganic ions and to a lesser extent soluble sugars; proline was not implicated in osmotic adjustment. Overall, two important mechanisms of salt tolerance in B. macrocarpa were identified: osmotic and apoplastic water adjustment.

Automated thresholding and analysis of microCT scanned bread dough

Computer aided x-ray microtomography is an increasingly popular method to investigate the structure of materials. Continuing improvements in the technique are resulting in increasingly larger data sets. The analysis of these data sets generally involves executing a static workflow for multiple samples and is generally performed manually by researchers. Executing these processes requires a significant time investment. A workflow which is able to automate the activities of the user would be useful. In this work, we have developed an automated workflow for the analysis of microtomography scanned bread dough data sets averaging 5 GB in size. Comparing the automated workflow with the manual workflow indicates a significant amount of the time spent (33% in the case of bread dough) on user interactions in manual method. Both workflows return similar results for porosity and pore frequency distribution. Finally, by implementing an automated workflow, users save the time which would be required to manually execute the workflow. This time can be spent on more productive tasks.

Identification of genome regions controlling cotyledon, pod wall/seed coat and pod wall resistance to pea weevil through QTL mapping

Pea weevil, Bruchus pisorum, is one of the limiting factors for field pea (Pisum sativum) cultivation in the world with pesticide application the only available method for its control. Resistance to pea weevil has been found in an accession of Pisum fulvum but transfer of this resistance to cultivated pea (P. sativum) is limited due to a lack of easy-to-use techniques for screening interspecific breeding populations. To address this problem, an interspecific population was created from a cross between cultivated field pea and P. fulvum (resistance source). Quantitative trait locus (QTL) mapping was performed to discover the regions associated with resistance to cotyledon, pod wall/seed coat and pod wall resistance. Three major QTLs, located on linkage groups LG2, LG4 and LG5 were found for cotyledon resistance explaining approximately 80 % of the phenotypic variation. Two major QTLs were found for pod wall/seed coat resistance on LG2 and LG5 explaining approximately 70 % of the phenotypic variation. Co-linearity of QTLs for cotyledon and pod wall/seed coat resistance suggested that the mechanism of resistance for these two traits might act through the same pathways. Only one QTL was found for pod wall resistance on LG7 explaining approximately 9 % of the phenotypic variation. This is the first report on the development of QTL markers to probe Pisum germplasm for pea weevil resistance genes. These flanking markers will be useful in accelerating the process of screening when breeding for pea weevil resistance.

First Report of Bituminaria Witches'-Broom in Australia Caused by a 16SrII Phytoplasma

Bituminaria bituminosa (L.) Stirt. is a perennial legume known as Arabian pea that is used as a forage in arid areas and for stabilization of degraded soils. It is widely distributed in the Mediterranean Basin with wider adaptation across the Canary Islands (4). In July 2010, during a survey for phytoplasma, some Canary Island B. bituminosa plants with typical phytoplasma symptoms, including stunted growth with small leaves, shortened internodes, and bushy growth, were found in seed multiplication nurseries at Medina, Perth, Western Australia (115°48.5'E; 32°13.2'S). Two samples from plants with clear disease symptoms and two visibly healthy plants were collected and total DNA was extracted with the Illustra DNA extraction kit Phytopure (GE Healthcare) according to the manufacturer's instructions. Direct and nested PCR were used to test the presence of phytoplasma 16S rDNA in samples with universal primers P1/P7 and R16F2n/R16R2, respectively (1,3). The PCR amplifications from all diseased samples yielded an expected product of 1.8 kb by direct and 1.2 kb by nested PCR, but not from the healthy plant samples. The direct PCR product was used as a template DNA in sequencing and the DNA sequence was deposited in the NCBI GenBank (Accession No. HQ404357). Sequence homology analysis indicated there was a perfect match between the two isolates. BLAST search of the NCBI GenBank revealed that B. bituminosa phytoplasma shares >99% sequence identity with Crotalaria witches'-broom phytoplasma (Accession No. EU650181.1), pear decline phytoplasma (Accession No. EF656453.1), and Scaevola witches'-broom phytoplasma (Accession No. AB257291.1). On the basis of BLAST analyses of 16S rRNA gene sequences, B. bituminosa phytoplasma in Western Australia appears to belong to the peanut witches'-broom group (16SrII-D) of phytoplasma. Restriction fragment length polymorphism analysis was also performed on nested PCR products of two samples of B. bituminosa phytoplasma by separate digestion with HaeIII, Hind6I, HpaII, MboI, RsaI, Tru9I, and T-HB8I restriction enzymes. Samples yielded patterns similar to alfalfa witches'-broom phytoplasma (Accession No. AF438413) belonging to subgroup 16SrII-D (2). To our knowledge, this is the first report of a phytoplasma of the 16SrII-D group infecting B. bituminosa in Australia and should be referred to as "Bituminaria witches'-broom phytoplasma" (BiWB). This report also indicates that the occurrence of the phytoplasma in B. bituminosa may be widespread in the Canary Islands and other species of Bituminaria might be susceptible to infection by Bituminaria witches'-broom phytoplasma. References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) A. J. Khan et al. Phytopathology 92:1038, 2002. (3) I.-M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:337, 2004. (4) P. Mendez et al. Grassland Sci. Eur. 11:300, 2006.

An epidemiological model for externally sourced vector-borne viruses applied to Bean yellow mosaic virus in lupin crops in a Mediterranean-type environment

A hybrid mechanistic/statistical model was developed to predict vector activity and epidemics of vector-borne viruses spreading from external virus sources to an adjacent crop. The pathosystem tested was Bean yellow mosaic virus (BYMV) spreading from annually self-regenerating, legume-based pastures to adjacent crops of narrow-leafed lupin (Lupinus angustifolius) in the winter-spring growing season in a region with a Mediterranean-type environment where the virus persists over summer within dormant seed of annual clovers. The model uses a combination of daily rainfall and mean temperature during late summer and early fall to drive aphid population increase, migration of aphids from pasture to lupin crops, and the spread of BYMV. The model predicted time of arrival of aphid vectors and resulting BYMV spread successfully for seven of eight datasets from 2 years of field observations at four sites representing different rainfall and geographic zones of the southwestern Australian grainbelt. Sensitivity analysis was performed to determine the relative importance of the main parameters that describe the pathosystem. The hybrid mechanistic/statistical approach used created a flexible analytical tool for vector-mediated plant pathosystems that made useful predictions even when field data were not available for some components of the system.

Growth responses of cool-season grain legumes to transient waterlogging

Transient waterlogging reduces the yield of cool-season grain legumes in several parts of the world. The tolerance of grain legumes to waterlogging may vary between and within species. This study investigated the effects of 7 days of waterlogging and subsequent recovery (10 days) on plant growth to evaluate the variation in tolerance among 7 cool-season grain legume species, in sand culture in glasshouse experiments. Additionally waterlogging tolerance of 6 faba bean genotypes was also evaluated. Tolerance to waterlogging as indicated by root and shoot growth (as % of drained controls) was ranked as follows: faba bean > yellow lupin > grass pea > narrow-leafed lupin > chickpea > lentil > field pea. Faba bean produced adventitious roots and aerenchyma leading to increased root porosity (9% gas volume per unit root volume). Among the 6 faba bean genotypes screened, accession 794 showed the best waterlogging tolerance, but it was also the slowest growing accession, which might have contributed to apparent tolerance (i.e. growth as % drained control). It is concluded that waterlogging tolerance in grain legumes varied between and within species, with faba bean being the most tolerant. The variation in tolerance identified within the limited set of faba bean genotypes evaluated suggests scope for further genetic improvement of tolerance in this species.

Response of chickpea (Cicer arietinum L.) varieties to time of sowing in Mediterranean-type environments of south-western Australia

Chickpea has become an important grain legume crop in Australia over the last decade. New varieties with improved seed yield and quality are being developed in Australia with varied phenological and agronomic traits. This study examined the optimum time of sowing of several desi chickpea varieties (Dooen, T1587, Sona and Tyson) varying in phenology over a range of dryland Mediterranean-type environments in south-western Australia. Chickpea showed good adaptation, particularly in the northern grain belt of Western Australia where growing conditions are warmer than southern areas. Seed yields varied widely depending on the time of sowing, location and seasonal conditions. Mean seed yields greater than 1000 kg/ha and up to 2000 kg/ha were achieved, but in some cases seed yields were less than 800 kg/ha. In the northern region, seed yield was almost doubled by sowing in early-May (1625 kg/ha) compared with late-June (754 kg/ha). In contrast to this, seed yields were generally lower in the southern regions and greater from late-June sowings (865 kg/ha) compared to earlier mid-May sowings (610 kg/ha). Seed yields were not clearly increased by altering sowing time to match the phenology of the variety to the growing season rainfall and temperatures, except at the early sowing times (April and early-May) where Tyson out-yielded all other varieties. This is most likely due to the lack of photoperiod-responsive, long-duration varieties to match early sowing and low temperatures limiting vegetative and reproductive growth in all varieties, especially in southern areas. However, it is likely that early flowering varieties will show greater adaptation and yield performance in short growing seasons, while later flowering varieties will be better suited to longer growing seasons. The study found that there were significant differences in the optimum sowing time between northern, central and southern sites, based on differences in mean daily temperatures and length of the growing season. Generally, the greatest seed yields were produced by sowing between mid to late June at southern sites, and early May at central and northern sites.

A water deficit during pod development in lentils reduces flower and pod numbers but not seed size

An experiment was conducted under controlled conditions in a glasshouse to determine the sensitivity of reproductive development of lentil (Lens culinaris Medikus) genotypes of different origins to water deficit. The 3 genotypes were Cassab (West Asia), Simal (South Asia), and ILL 7979 a crossbred between a West Asian genotype and a South Asian genotype. Two watering treatments, a well-watered control and a water-deficit treatment, were imposed from the beginning of podding. Leaf water relations, total dry matter production, leaf area, and number of flowers, pods, and seeds were measured from podding to maturity. In the well-watered plants the leaf water potential (ψleaf) before sunrise ranged from −0.6 to −0.8 MPa. When subjected to water deficit, ψleaf fell to about −3.0 MPa. Genotypes did not show variation in vegetative growth or seed yield under either well-watered or water-deficit conditions, but they differed significantly in the number of flowers, fruiting nodes, pods, and seeds, and harvest index (HI). Seed size in Cassab was 61% larger than ILL 7979 and 105% larger than Simal. The small-seeded genotypes produced the highest number of fruiting nodes and hence a greater number of flowers, pods, and seeds. Seed size was positively correlated with seed growth rate (r = 0.77**) and seed fill duration (r = 0.45*). The water deficit reduced plant height by about 20%, leaf area by 48–81%, and total dry matter by about 60% compared with well-watered plants. The water deficit reduced flower number by 35–46% and increased seed abortion (empty pods) by 17–46%. The water deficit had no effect on the maximum seed growth rate, seed fill duration, or final seed size in any of the 3 genotypes. Therefore, the 70% reduction in seed yield induced by the water deficit was primarily due to a reduction in pod and seed numbers (by 59–70%) rather than individual seed growth rate and seed size.

Physiological and seed yield responses to water deficits among lentil genotypes from diverse origins

The effect of water deficits at 2 growth stages on the physiology and growth of lentil (Lens culinaris Medikus subsp. culinaris) genotypes bred/selected for 3 regions was examined in a glasshouse experiment. The water regimes imposed were: (i) a well-watered control, (ii) water withheld at flowering, from 72 to 93 days after sowing (DAS), and (iii) water withheld from podding (93 DAS) to maturity. The genotypes were a West Asian genotype released in Australia (Cassab), 2 South Asian Nepali cultivars (Khajura 2 and Simal), and 3 crossbreds between West Asian and South Asian parents (ILL 6829, ILL 7979, and ILL 7982). ILL 7979 and Simal had significantly greater total dry matter, water use, seed yield, number of pods and seeds per plant, and harvest index (HI) than the other genotypes under well-watered conditions. Water deficits reduced seed yield by up to 60% in the crossbreds and the South Asian cultivar, Simal. However, seed yield was increased by the water deficit at flowering and the water deficit at podding in the West Asian genotype, Cassab, and the South Asian genotype, Khajura 2, respectively. In the other genotypes, withholding water at flowering or podding reduced leaf area (48–55%), total dry matter (32–50%), flower production (22–55%), and number of pods and seeds (27–66%), with significantly higher flower drop and empty pods when water was withheld. The higher seed yield in Cassab and Khajura 2 when water was withheld was related to the production of more flowers and the maintenance of pod and seed set when they were re-watered after the period of water deficit. When water was withheld during flowering, the West Asian genotype Cassab and the crossbred ILL 6829 used less water and hence maintained a high leaf water potential (ψleaf), whereas ψleaf decreased earlier to lower values in the crossbred ILL 7979 and the South Asian genotypes Khajura 2 and Simal. There were no significant differences in leaf net photosynthesis (PN), or stomatal conductance (gS), among genotypes during flowering and early podding, but PN and gS were reduced by 22–38 and 19–67%, respectively, when water was withheld. The lower ψleaf in ILL 7979, Simal, and Khajura 2 induced greater osmotic adjustment (OA) during the drying cycle at flowering, whereas there was no or little OA when water was withheld at podding. Variation in physiological traits (PN, gS, OA) under both watering regimes was not directly related to seed yield, but seed number was related to seed yield under both well-watered and water-deficit conditions.

Botrytis grey mould of chickpea: a review of biology, epidemiology, and disease management

Botrytis grey mould (BGM), caused by Botrytis cinerea Pers. ex. Fr., is an economically important disease of chickpea (Cicer arietinum L.), especially in areas where cool, cloudy, and humid weather persists. Several epidemics of BGM causing complete crop loss in the major chickpea-producing countries have been reported. The pathogen B. cinerea mainly survives between seasons on infected crop debris and seeds. Despite extensive investigations on pathological, physiological, and molecular characteristics of B. cinerea causing grey mould type diseases on chickpea and several other hosts, the nature of infection processes and genetic basis of pathogen variability have not been clearly established. This lack of information coupled with the need for repeated application of chemical fungicides forced the deployment of host plant resistance (HPR) as a major option for BGM management. Effective and repeatable controlled-environment and field-screening techniques have been developed for identification of HPR. Of the selected portion of chickpea germplasm evaluated for BGM resistance, only few accessions belonging to both cultivated and wild Cicer spp. were tolerant to BGM, and the search for higher levels of disease resistance continues. Fungicide application based on disease predictive models is helpful in precision-based fungicide application. Integrated disease management (IDM) of BGM has proved more effective than any of the individual disease management components in large-scale, on-farm studies conducted in India, Nepal, and Bangladesh. Further information on the biology of B. cinerea and epidemiology of the disease is needed to strengthen the IDM programs. In this paper the biology of B. cinerea including its variability, epidemiology of BGM, identified sources of resistance, and other management options, and available information on biochemical and genetic basis of disease resistance have been reviewed with a mention of future research priorities.

RAMP based fingerprinting and assessment of relationships among Australian narrow-leafed lupin (Lupinus angustifolius L.) cultivars

Narrow-leafed lupin is a major winter grain legume crop in the Australian farming system and a number of commercial cultivars are currently available to growers. A significant level of polymorphism was detected in narrow-leafed lupin cultivars by the randomly amplified microsatellite polymorphism (RAMP) approach, suggesting that cultivars harbour considerable DNA variation. Seventy-seven cultivar-specific markers were found among the 23 lupin cultivars examined and a dichotomous fingerprinting key was developed for the molecular identification of lupin cultivars. Cluster analysis of pairwise distance matrix computed from RAMP profiles grouped the 23 cultivars into 4–5 clusters, which generally agreed with their pedigree relationships.

Ascochyta blight of chickpea (Cicer arietinum L.): a review of biology, pathogenicity, and disease management

Ascochyta blight (AB), caused by Ascochyta rabiei is a major disease of chickpea (Cicer arietinum L.), especially in areas where cool, cloudy, and humid weather persists during the crop season. Several epidemics of AB causing complete yield loss have been reported. The fungus mainly survives between seasons through infected seed and in infected crop debris. Despite extensive pathological and molecular studies, the nature and extent of pathogenic variability in A. rabiei have not been clearly established. Accumulation of phenols, phytoalexins (medicarpin and maackiain), and hydrolytic enzymes has been associated with host-plant resistance (HPR). Seed treatment and foliar application of fungicides are commonly recommended for AB management, but further information on biology and survival of A. rabiei is needed to devise more effective management strategies. Recent studies on inheritance of AB resistance indicate that several quantitative trait loci (QTLs) control resistance. In this paper we review the biology of A. rabiei, HPR, and management options, with an emphasis on future research priorities.

Geographical patterns of genetic variation in the world collections of wild annual Cicer characterized by amplified fragment length polymorphisms

Cicer reticulatum, C. echinospermum, C. bijugum, C. judaicum, C. pinnatifidum, C. cuneatum and C. yamashitae are wild annual Cicer species and potential donors of valuable traits to improve chickpea (C. arietinum). As part of a large project to characterize and evaluate wild annual Cicer collections held in the world gene banks, AFLP markers were used to study genetic variation in these species. The main aim of this study was to characterize geographical patterns of genetic variation in wild annual Cicer germplasm. Phylogenetic analysis of 146 wild annual Cicer accessions (including two accessions in the perennial C. anatolicum and six cultivars of chickpea) revealed four distinct groups corresponding well to primary, secondary and tertiary gene pools of chickpea. Some possible misidentified or mislabelled accessions were identified, and ILWC 242 is proposed as a hybrid between C. reticulatum and C. echinospermum. The extent of genetic diversity varied considerably and was unbalanced between species with greatest genetic diversity found in C. judaicum. For the first time geographic patterns of genetic variation in C. reticulatum, C. echinospermum, C. bijugum, C. judaicum and C. pinnatifidum were established using AFLP markers. Based on the current collections the maximum genetic diversity of C. reticulatum, C. echinospermum, C. bijugum and C. pinnatifidum was found in southeastern Turkey, while Palestine was the centre of maximum genetic variation for C. judaicum. This information provides a solid basis for the design of future collections and in situ conservation programs for wild annual Cicer.

Growth and seed yield of lentil (Lens culinaris Medikus) genotypes of West Asian and South Asian origin and crossbreds between the two under rainfed conditions in Nepal

Nineteen diverse lentil genotypes, 8 originating from South Asia, 6 from West Asia, and 5 crossbreds using parents from South Asia and West Asia (or other Mediterranean environments), were evaluated for growth, phenology, yield, and yield components at Khumaltar in the mid-hill region of Nepal. Additionally, dry matter production, partitioning, root growth and water use of 8 selected genotypes from the 3 groups were measured at key phenological stages. The seed yield of the West Asian genotypes was only 330 kg/ha, whereas the South Asian genotypes produced a mean seed yield of 1270 kg/ha. The crossbreds had a significantly (P = 0.05) greater seed yield (1550 kg/ha) than the South Asian genotypes. The high seed yield of both the South Asian and crossbred genotypes was associated with rapid ground cover, early flowering and maturity, a long reproductive period, a greater number of seeds and pods, high total dry matter, greater harvest index, and high water use efficiency. West Asian genotypes, on the other hand, flowered 43 days later, matured 15 days later, and had a shorter reproductive period (by 22 days) than the crossbred and South Asian genotypes. The 23% greater seed yield in the crossbreds compared with the South Asian genotypes was the result of a similar increase in seed size (weight per seed). There were no significant differences in total root length (mean 4.7 km/m2), root dry matter (mean 95.5 g/m2), or water use among the 3 groups during the major part of the growing period. There was a significant difference in total water use due to the longer growing season of the West Asian genotype ILL 7983 and its ability to use late-season rainfall. Maximum water use efficiencies for seed yield of 7.0 kg/ha.mm and for above-ground dry matter of 18.9 kg/ha.mm were comparable with those reported in India and the Mediterranean environments of south-western Australia and Syria.

Genotype by environment studies across Australia reveal the importance of phenology for chickpea (Cicer arietinum L.) improvement

Chickpea (Cicer arietinum L.) genotypes comprising released cultivars, advanced breeding lines, and landraces of Australian, Mediterranean basin, Indian, and Ethiopian origin were evaluated at 5 representative sites (Merredin, WA; Minnipa, SA; Walpeup, Vic.; Tamworth, NSW; Warwick, Qld) over 2 years. Data on plant stand, early vigour, phenology, productivity, and yield components were collected at each site. Site yields ranged from 0.3 t/ha at Minnipa in 1999 to 3.5 t/ha at Warwick in 1999. Genotype by environment (G × E) interaction was highly significant. Principal components analysis revealed contrasting genotype interaction behaviour at dry, low-yielding sites (Minnipa 1999, Merredin 2000) and higher rainfall, longer growing-season environments (Tamworth 2000). Genotype clusters performing well under stress tended to yield well at all sites except Tamworth in 2000, and were characterised by early phenology and high harvest index, but were not different in terms of biomass or early vigour. Some of these traits were strongly influenced by germplasm origin. The material with earliest phenology came from Ethiopia, and southern and central India, with progressively later material from northern India and Australia, and finally the Mediterranean. There was a delay between the onset of flowering and podding at all sites, which was related to average temperatures immediately post-anthesis (r = –0.81), and therefore larger in early flowering material (>30 days at some sites). Harvest index was highest in Indian and Ethiopian germplasm, whereas crop height was greatest in Australian and Mediterranean accessions. Some consistently high yielding genotypes new to the Australian breeding program were identified (ICCV 10, BG 362), and the existing cultivar Lasseter was also confirmed to be very productive.

Utilisation of wild Cicer in chickpea improvement — progress, constraints, and prospects

Efforts to improve the yield and quality of cultivated chickpea (Cicer arietinum L.) are constrained by a low level of intraspecific genetic diversity. Increased genetic diversity can be achieved via the hybridisation of the cultivated species with the unimproved 'wild' relatives from within the 43 species of the Cicer genus. To date, the 8 species sharing an annual growth habit and chromosome number with C. arietinum have been the primary focus of screening and introgression efforts. Screening of these species has uncovered morphological characteristics and resistance to a number of abiotic and biotic stresses that are of potential value to chickpea improvement programs. Detailed analysis of protein and DNA, karyotyping, and crossability studies have begun to elucidate the relationships between the annual Cicer species. In comparison, perennial species have received little attention due to difficulties in collection, propagation, and evaluation. This review discusses the progress towards an understanding of genetic relationships between the Cicer species, and the introgression of genes from the wild Cicer species into the cultivated species.

Method of phosphorus fertiliser application and row spacing on grain yield of faba bean (Vicia faba L.)

Yield responses of faba bean (Vicia faba L.) cv. Fiord to applications of fertiliser phosphorus (P), as superphosphate, were measured in 2 field experiments. The P was either (i) placed with the seed while sowing at 6 cm depth and also cultivating at 3–4 cm below the seed (drilled P) or (ii) placed 3–4 cm below the seed while sowing at 6 cm depth (banded P). This was done when the seed and fertiliser were placed in rows at either the standard 19 cm apart (current recommendation) or 38 cm apart (makes it easier to sow into the stubble of the previous crop). Yield of dried shoots and seed (grain) increased with increasing amount of P applied (0–30 kg P/ha in experiment 1, 0–45 kg P/ha in experiment 2), but were unaffected by the method of P application or spacing between seed and fertiliser rows. Therefore, (i) up to 45 kg P/ha can be drilled with the seed while sowing faba bean crops (current farmer practice) and (ii) faba bean can be sown and fertilised at 38-cm spacings making it easier to sow into the stubble of the previous crop than the 19-cm spacing currently being practiced.

Grain yield responses of faba bean (Vicia faba L.) to applications of fertiliser phosphorus and zinc

Seed (grain) yield responses of faba bean (Vicia faba L. cv. Fiord) to applications of fertiliser phosphorus (0, 5, 10, 20 and 40 kg P/ha as triple superphosphate) and zinc (0, 0.5, 1 and 2 kg Zn/ha as zinc oxide) were measured in 3 field experiments conducted in 1997 and 1998 on neutral to alkaline soils in south-western Australia. Additions of fertiliser phosphorus significantly (P<0.001) increased grain yields by about 50 and 100% in 2 experiments, but in the third experiment differences in grain yield due to applications of fertiliser phosphorus were not significant (P>0.05). Increases in grain yields due to zinc fertiliser were small (<10%) and were only significant (P<0.05) in 1 experiment. This suggests the 3 sites chosen had adequate soil zinc for grain production of faba bean. In 1 experiment the increase in grain yield due to addition of phosphorus fertiliser was due to an increase in the number of pods per plant; numbers of seed per pod and mean seed weight were unaffected by additions of phosphorus and zinc fertiliser. Adding phosphorus and zinc fertiliser increased concentrations of both elements in grain, but had no effect on the concentrations of other nutrient elements (N, K, S, Ca, Mg, Na, Cu, Mn, Fe) measured in grain. These findings support results of a previous study in Western Australia indicating that phosphorus is the major nutrient element deficiency for grain production of faba bean in neutral to alkaline soils.

Remobilisation of carbon and nitrogen supports seed filling in chickpea subjected to water deficit

In the Mediterranean-type environment of south-western Australia, pod filling of chickpea occurs when net photosynthesis and nitrogen fixation is low as a result of the onset of terminal drought. Remobilisation of carbon (C) and nitrogen (N) from vegetative parts to developing seed may be an important alternative source of C and N for seed filling. The contribution of stored pre-podding C and N to seed filling was studied by labelling the vegetative tissues with the stable isotopes, 13C and 15N, prior to podding and following their subsequent movement to the seed. In ICCV88201, an advanced desi breeding line, 9% of the C and 67% of the N in the seed were derived from pre-podding C and N in well-watered plants compared with 13% of the seed C and 88% of the seed N in water-stressed plants. Furthermore, the contribution of pre-podding C and N was higher for earlier set compared with later set seeds. Pre-podding C and N were derived predominantly from the leaves with relatively little from the stems, roots, and pod walls. Genotypic variation in remobilisation ability was identified in contrasting desi (Tyson) and kabuli (Kaniva) cultivars. In well-watered Tyson, 9% of the seed C and 85% of the seed N were remobilised from vegetative tissues compared with 7% of the seed C and 62% of seed N in well-watered Kaniva. Water deficit decreased the amount of C remobilised by 3% in Tyson compared with 66% in Kaniva, whereas the total amount of N remobilised was decreased by 11% in Tyson and 48% in Kaniva. This was related to the maintenance of greater sink strength in Tyson, in which the number of filled pods was reduced by 66% in stressed plants compared with a 91% decrease in Kaniva. This indicates that better drought tolerance in desi genotypes is partly a consequence of better remobilisation and higher pod number. These studies show that C and N assimilated prior to podding can supplement the supply of current assimilates to the filling seed in both well-watered and water-stressed chickpea. Remobilisation of pre-podding N is an essential source of N for seed filling irrespective of environmental stress.

Seed growth of desi and kabuli chickpea (Cicer arietinum L.) in a short-season Mediterranean-type environment

The influence of terminal drought on the seed growth of 3 chickpea (Cicer arietinum L.) genotypes was examined in a field experiment at Merredin, Western Australia. Tyson, a small-seeded desi cultivar, ICCV88201, a desi breeding line (sister line to the recently released Sona cultivar) with medium-sized seed, and Kaniva, a kabuli cultivar with large seed, were grown under rainfed and irrigated conditions. In the rainfed plots, leaf water potential had decreased from above –1.2 MPa to about –2.5 MPa and net photosynthesis from 21 to 29 µmol CO2/m2. s to below 10 µmol CO2/m2.s, by the time seed filling commenced. Rainfed plants had significantly fewer pods than irrigated plants, regardless of genotype. In rainfed plants average seed weight was reduced by 19, 23 and 34% and yield by 74, 52 and 72% in Tyson, ICCV88201, and Kaniva respectively. Individual pods were tagged at pod set on previously-selected representative plants and were weighed separately from the rest of the plant over 6 subsequent harvests so that the rate and duration of seed fill could be measured. Genotypic differences in the maximum rate of seed fill were found to exist in chickpea. In both irrigated and rainfed conditions, Kaniva had the highest maximum rate of seed fill followed by ICCV88201 and Tyson. Both the rate and duration of seed growth were reduced in the rainfed plants, regardless of genotype. Reductions in the dry weight of the pod shell suggest that the remobilisation of dry matter from the pod may contribute 9–15% of the seed weight in rainfed chickpea.

Cool season grain legumes for Mediterranean environments: the effect of environment on non-protein amino acids in Vicia and Lathyrus species

Variation among a range of potentially deleterious non-protein amino acids found in the seeds of the genera Vicia and Lathyrus was determined by growing species at up to 31 sites covering the range of environments experienced in the cropping region of south-west Australia. γ-Glutamyl-S-ethenyl cysteine (GEC) concentrations in V. narbonensis were correlated to seed sulfur levels (r = 0.95, P < 0.001) in 1 of 2 genotypes, and shown to increase under conditions of increasing soil sulfur availability, pH, clay content, cation exchange capacity, concentration of exchangeable cations, and salinity. To capitalise on the agricultural potential of this species we recommend the selection of genotypes that break the linkage between GEC and seed sulfur. In Lathyrus species the degree of variation of β-N-oxalyl-L-α, β-diaminopropionic acid (ODAP) in the seed appears to be proportional to the species mean ODAP concentration; L. ochrus was more responsive than L. sativus, which was in turn more responsive than L. cicera. Seed ODAP concentrations in L. ochrus and L. sativus were positively correlated with soil phosphorus, and negatively correlated with clay content and salinity, and may constrain the species potential for human and animal consumption. In V. ervilia seed, canavanine concentrations were extremely variable in the field (0.01–0.17%), but are unlikely to reduce the stockfeed potential of this species for either monogastrics or ruminants.

Adaptation and seed yield of cool season grain legumes in Mediterranean environments of south-western Australia

A range of cool season grain legume species have shown considerable potential for soils unsuitable for the production of narrow-leafed lupin (Lupinus angustifolius L.) at limited sites in the Mediterranean-type environments of south-western Australia. In this study the adaptation of these grain legume species was compared by measuring crop phenology, growth, and yield in field experiments at a total of 36 sites over 3 seasons, with the aim of identifying species with suitable adaptation and seed yield for specific environments. The grain legumes examined appeared to fall into 3 categories: (i) field pea (Pisum sativum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.), and narbon bean (Vicia narbonensis L.) clearly had superior seed yield to the other species over a wide number of sites and years across south-western Australia (mean 1.0–2.3 t/ha); (ii) albus lupin (Lupinus albus L.), desi chickpea (Cicer arietinum L.), and Lathyrus cicera, L. sativus, and L. ochrus produced seed yields of 1–1.3 t/ha; and (iii) red lentil (Lens culinaris L.), bitter vetch (Vicia ervilia), and kabuli chickpea (Cicer arietinum L.) generally produced the lowest yields (0.6–1.0 t/ha). There were clear species × environment interactions. At low-yielding sites (<1.4 t/ha), field pea was the highest yielding species, while faba bean often produced the highest seed yields under more favourable conditions at high yielding sites. Lentil, bitter vetch, Lathyrus spp., and desi chickpea showed average response to increasing mean site yield. Soil pH and clay content and rainfall were the environmental factors identified as the most important in determining seed yields. Soil pH and clay content appeared to be especially important in the adaptation of lentil, narbon bean, bitter vetch, and kabuli chickpea, with these species performing best in soils with pH >6.0 and clay contents >15%. Seed yields were positively correlated with dry matter production at maturity across a number of sites (r2 = 0.40, P < 0.01). Future improvements in seed yield of these species are likely to come from management practices that increase dry matter production such as increased plant density and early sowing, and through the development of genotypes with greater tolerance to low winter temperatures, and more rapid phenology, canopy development, and dry matter production than existing commercial cultivars.

Cool season grain legumes for Mediterranean environments: species × environment interaction in seed quality traits and anti-nutritional factors in the genus Vicia

Seed size and protein, sulfur (S), total phenolics, condensed tannins, and proteinase inhibitor concentrations were measured in 4 Vicia species (V. faba, V. sativa, V. ervilia, V. narbonensis) grown at up to 30 locations in the south-west of Western Australia. There was a species × environment interaction for all seed traits, and this was reflected in the relationships with environmental parameters and other seed traits within each species. For V. faba, it was difficult to account for the production of seed quality traits or antinutritional factors on the basis of descriptive environmental parameters such as climate or edaphic characteristics. The remaining species were more responsive to environmental factors measured throughout the study. Seed size was negatively associated with soil salinity in V. narbonensis and V. ervilia. Seed protein content was positively correlated with soil total nitrogen (N) and phosphorus (P) in V. sativa and V. ervilia, and also with electrical conductivity, pH, and exchangeable cations in V. ervilia. The S content of V. narbonensis seeds increased with increasing soil S availability, while the opposite occurred in V. ervilia and V. sativa. Total phenolics were positively associated with total N and P in V. sativa, and negatively correlated with soil clay content, S, and salinity in V. ervilia. Proteinase inhibitors in V. sativa were positively associated with soil salinity, while the opposite was the case in V. ervilia. Proteinase inhibitors in V. ervilia were also negatively correlated with pH, clay content, total N, and exchangeable cations, whereas the total N and exchangeable cations were associated with increasing proteinase inhibitors in V. narbonensis. These complex and contrasting relationships between antinutritional factors and environmental parameters suggest that the carbon: nutrient balance hypothesis, the pre-eminent paradigm used to predict plant resource allocation to N and C based defence, may not be applicable to the seeds of legumes. The agricultural significance of the species ´ environment interaction above depends on the seed characteristic in question. Increased S uptake by V. narbonensis relative to V. ervilia and V. sativa may advantage this species as a fodder crop, given that these species are targeted at alkaline, fine-textured soils where soil S availability is likely to be relatively high. However, in the seed of V. narbonensis and V. sativa, fluctuating concentrations of polyphenolics and condensed tannins occasionally reach the relatively high levels recorded in V. faba, and other anti-nutritional factors not withstanding, this may limit their palatability to monogastrics.

Growth, seed yield and water use of faba bean (Vicia faba L.) in a short-season Mediterranean-type environment

Summary. A number of studies conducted in Western Australia have shown that faba bean has considerable potential as a pulse crop in the low to medium rainfall cropping regions (300–450 mm/year). However, its yield is variable and can be low in seasons when rainfall is less than average. Traits associated with the adaptation of 10 diverse faba bean genotypes to low rainfall, Mediterranean-type environments were evaluated at Merredin in south-western Australia over 2 contrasting seasons. Plant density was varied with seed size to ensure all genotypes achieved similar canopy development and dry matter production. Time to flowering appeared to be the most important trait influencing seed yield of faba bean in this environment. Seed yield was significantly correlated with time to 50% first flower in 1994 and 1995 (r2 = 0.61 and 0.82 respectively, P<0.01). In the dry 1994 season, rapid leaf area development in ACC286 allowed a greater absorption of photosynthetically active radiation resulting in more dry matter accumulation than other genotypes. ACC286 also had greater root length density at 20–30 cm depth compared with Icarus and the standard cultivar Fiord. There were no significant differences in total water use between the genotypes examined, although the pattern of water use varied markedly. The ratio of pre- to post-flowering water use was about 1:1 in the early flowering and high yielding ACC286 and 2.6 :1 for the late maturing, low yielding Icarus. Seed yield and harvest index were positively correlated with post-flowering water use (r2 = 0.75 and 0.71 respectively). Above-average rainfall in 1995 resulted in increased yield of all genotypes, particularly ACC286 which again produced the highest yields. Early flowering genotypes with rapid dry matter accumulation in the seedling stages (such as ACC286) could widen the adaptation of faba bean to low rainfall, Mediterranean-type environments and situations where sowing is delayed.

Responses of faba bean (Vicia faba L.) to sowing rate in south-western Australia II Canopy development, radiation absorption and dry matter partitioning

Sowing rate influences plant density, canopy development, radiation absorption, dry matter production and its partitioning, and seed yield. The canopy development, radiation interception, and dry matter partitioning of faba bean (cv. Fiord) were examined using 6 sowing rate treatments from 70 to 270 kg/ha in field experiments conducted over 3 years at Northam as part of a larger investigation of sowing rate responses in faba bean in south-western Australia. High sowing rates resulted in significantly earlier canopy closure, larger green area indexes, more radiation absorption, more dry matter accumulation particularly during the early vegetative stages, and greater seed yield than treatments where a low plant density was established. The results suggest that further increases in canopy development, radiation absorption, dry matter accumulation, and seed yield are possible by using sowing rates in excess of 270 kg/ha. The rate of node appearance was relatively constant within and across seasons (1 every 65·9 degree-days), whereas the number of branches per plant declined with increasing plant density, and less branches survived through to maturity at high density. The peak photosynthetically active radiation absorption (75-85%) measured at green area index of 2·9-3·8 in the highest sowing rate treatment in this study is similar to previous reports for other crops. The estimated radiation use efflciency (1·30 g/MJ) was constant across sowing rate treatments and seasons. High sowing rates produced tall crops with the lowest pods further from the soil surface than those at low plant density, and hence, mechanical harvesting was easier. The growth of individual plants may have been limited by the low growing season rainfall (266-441 mm) and/or low soil pH (5·0 in CaCl2) at the site, and competition between plants for radiation was probably small even at the highest sowing rate. Early canopy closure and greater dry matter production with high sowing rates may also cause greater suppression of weeds and aphids.

Adaptation of lentil (Lens culinaris Medik) to short season Mediterranean-type environments: response to sowing rates

The growth and seed yield response of lentil (cv. Digger) to sowing rate (20-120 kg/ha) was studied at 13 sites over 3 seasons in the cropping regions of south-western Australia. The economic optimum plant density was estimated by fitting an asymptotic model to the data and calculating the sowing rate above which the cost for additional seed was equivalent to the revenue that could be achieved from the extra seed yield produced, assuming a 10% opportunity cost. On average across all sites and seasons, only 51% of sown seeds emerged. Increasing sowing rate resulted in greater dry matter production at ˚owering and maturity, and fewer pods per plant. Harvest index (0·31-0·36), number of seeds per pod (1·13-1·84), and mean seed weight (2·9-3·6 g/100 seeds) remained relatively stable with changes in sowing rate. The asymptotic models fitted to seed yields accounted for 1-73% of the total variance in the data, except at one site where a model could not be found to provide an adequate fit to the data. In addition to this site, another 5 sites were excluded from further consideration where the percentage of variance accounted for was <25% or the predicted optimum densities and seed yield potentials were well beyond the range of the data. The economic optimum of the remaining 7 sites ranged from 96 to 228 plants/m2, with a mean of 146 plants/m2. These results suggest that lentil yields may be improved by increasing sowing rates beyond those currently targeted in southern Australia (100-125 plants/m2). On the basis of these results, targeting a density of about 150 plants/m2 by using a sowing rate of approximately 90-110 kg/ha is recommended, depending on mean seed weight and germination percentage of the seed. Even higher sowing rates may be optimum where the growing conditions are unfavourable and individual plant growth is limited.

Adaptation of lentil (Lens culinaris Medik.) to Mediterranean-type environments: effect of time of sowing on growth, yield, and water use

This study examined the adaptation of lentil (Lens culinaris Medik. cv. Digger) to dryland Mediterranean-type environments of southern Australia and determined the effect of time of sowing on growth, yield, and water use. Phenology, canopy development, radiation absorption, dry matter production and partitioning, seed yield, and water use were measured from a range of sowing times at a number of field locations in south-western Australia in 1994, 1995, and 1996. Contrary to previous results with poorly adapted cultivars, our study showed that lentil is well adapted to low to medium rainfall regions (300-500 mm/year) of south-western Australia and that seed yields greater than 1·0 t/ha and up to 2·5 t/ha can be achieved when sown early. Even in the dry season of 1994 when May-October rainfall was <200 mm, yields of approximately 1·0 t/ha were produced from early sowings. Seed yields were reduced with delayed sowing at rates of 4-29 kg/ha · day. Sowing in late April or early May allowed a longer period for vegetative and reproductive growth, rapid canopy development, greater absorption of photosynthetically active radiation, more water use, and, hence, greater dry matter production, seed yield, and water use efficiency than when sowing was delayed. Early-sown lentils began flowering and filling seeds earlier in the growing season, at a time when vapour pressure deficits and air temperatures were lower, and used more water in the post-flowering period when compared to those treatments where sowing was delayed. The values of water use efficiency for dry matter and grain production, and transpiration efficiency, for early-sown lentil (up to 30 kg/ha · mm, 11 kg/ha · mm, and 20 kg/ha · mm, respectively) were comparable to those reported for cereal and other grain legume crops in similar environments. The development of earlier flowering cultivars than Digger with greater dry matter production together with improved agronomic packages will increase and stabilise lentil yields in low rainfall environments of southern Australia.

Responses of faba bean (Vicia faba L.) to sowing rate in south-western Australia. I. Seed yield and economic optimum plant density

Sowing rate influences plant establishment, growth, seed yield, and the profitability of a crop. However, there is limited published information on the optimum sowing rate and plant density for faba bean in Australia. The response of the growth and seed yield of faba bean (cv. Fiord) to sowing rate (70-270 kg/ha) was examined in 19 field experiments conducted over 3 years in south-western Australia. The economic optimum plant density was estimated at each site by fitting an asymptotic model to the data and calculating the point where the cost of extra seed equalled the return from additional seed yield, allowing a 10% opportunity cost for the extra investment. On average across all sites and seasons, only 71% of the seeds sown emerged. Increasing sowing rate resulted in more dry matter production at first flower and at maturity, and at about half of the sites there was a small trend of reduced harvest index. In general, the mean number of seeds per pod (1·8-2·6) and mean seed weight (32-45 g/100 seeds) were unaffected by sowing rate. As sowing rate increased, the number of pods per plant (5-35) generally decreased, but this was compensated by the large plant population and more pods per unit area. The asymptotic models fitted to the seed yield data accounted for 15-81% of the variance. In 8 experiments, the models indicated that yield was continuing to increase substantially as sowing rate increased at the largest sowing rate treatment. The estimated optimum plant densities in these experiments were beyond the range of the data or had large standard errors and, hence, were excluded from any further consideration. Among the remaining 11 experiments, the estimated optimum plant densities varied from 31 to 63 plants/m2, with a mean of 45 plants/m2. This study demonstrates that targeting sowing rates greater than the current commercial practice for faba bean in southern Australia of 15-30 plants/m2 results in more yield and profit. Additional experiments are required with sowing rates in excess of 270 kg/ha to estimate accurately the optimum plant density for faba bean. Fungal diseases were either absent or controlled with fungicides in these experiments but the interactions between disease, time of sowing, and sowing rates also deserve further attention.

Pulse production in Australia past, present and future

Summary. Several cool- and warm-season pulse crops (grain legumes) are grown in rotation with cereals and pasture forming sustainable farming systems in Australia. Australian pulse production has increased rapidly over the past 25 years to about 2 x 106 t/year, mainly because of the increase in the area and yield of lupin production for stockfeed purposes. Pulses currently comprise only 10% of the cropping areas of Australia and this could be expanded to 16% as there are large areas of soil types suitable for a range of pulse crops and new better-adapted pulse varieties are becoming available. Cool-season pulses will continue to dominate pulse production in Australia and the majority of the expansion will probably come from chickpea and faba bean industries. There appears to be no major constraint to pulse production in Australia that cannot be addressed by breeders, agronomists and farmers. Of the current major pulse crops, field pea faces the most number of difficulties, in particular the lack of disease management options. A recent strategic plan of the Australian pulse industry predicts the production of 4 x 106 t/year by 2005 but this will largely depend upon export demand and pulse prices. It is predicted that the growth in pulse production will come from increased productivity in the existing areas, from 1.0 to 1.4 t/ha, through improvements in crop management and the development of superior varieties. The area of pulse production will also expand by an additional 1.2 x 106 ha probably yielding 1.0 t/ha. If trends in grazing stock prices continue, the increased area under pulse production will mostly come at the expense of those areas under unimproved pasture and continuous cereal cropping.

Grain yield and water use efficiency of early maturing wheat in low rainfall Mediterranean environments

Wheat cultivars with very early maturities appropriate for late sowings in low-rainfall (<325 mm) short-season environments are currently unavailable to wheat growers in the eastern margin of the cropping region of Western Australia. A demonstration that very early-maturing genotypes can out-perform current commercial cultivars would open new opportunities for breeding programs to select very early-maturing, high- and stable-yielding cultivars for these environments. Six field experiments were conducted over 4 seasons at 2 low-rainfall sites in Western Australia to investigate crop growth, grain yield, and water use efficiency of very early-maturing genotypes compared with current commercial cultivars when sown after 1 June. Very early-maturing genotypes reached anthesis up to 24 days (328 degree-days) earlier than the current cultivars, produced less leaves, had similar yields and dry matter, and maintained high water use efficiencies. On average across seasons and locations the very early-maturing genotypes (W87–022–511, W87–114–549, W87–410–509) yielded more than the later maturing cultivars Gamenya and Spear (190 v. 160 g/m2) but they were similar to the early-maturing commercial cultivars Kulin and Wilgoyne (191 g/m2). Very early-maturing genotypes generally had a higher harvest index and produced fewer spikelets, but heavier and more grains, than Kulin and Wilgoyne. There were only small differences in total water use between very early-maturing genotypes and commercial cultivars; however, very early-maturing genotypes used less water in the pre-anthesis period and more water in the post-anthesis period than the later maturing genotypes, and hence, experienced less water deficit during the grain-filling period. This study indicates that there is a role for very early-maturing genotypes in low-rainfall short-season environments, when the first autumn rains arrive late (after 1 June).

Narbon bean (Vicia narbonensis L.): a promising grain legume for low rainfall areas of south-western Australia

The phenology, growth, seed yield and yield components of a number of introduced narbon bean (Vicia narbonensis L.) accessions and F9 breeding lines were compared with faba bean (Vicia faba L. cv. Fiord) or field pea (Pisum sativum L. cv. Dundale) at 3 sites in 2 seasons. All narbon bean accessions had slow development, for example all accessions reached 50% flowering 9-35 days later than faba bean or field pea depending on the accession, site and season. Dry matter production near flowering ranged from 1.0 to 2.3 tlha and the growth of the best accessions was comparable with faba bean. In general, the accession ATC 60114 collected in the Beka'a Valley, Lebanon, produced the greatest seed yield across the sites and seasons (on average 1.52 t/ha). In 1993, the best narbon bean accession produced seed yields that ranged from 59% of the faba bean seed yield at the wettest site to 121% at the driest site. In the following year, one of the driest in decades, 6 accessions produced seed yields of more than 1.0 t/ha, similar to field pea. Seed yield was negatively correlated with days to flowering, podding and maturity, suggesting that yield could be improved by selecting for more rapid development. Most accessions retained the majority of their leaves at maturity, but showed some degree of pod shattering and a moderate level of lodging at maturity. Genotypic variation in all these characters was evident. Further selection and breeding, together with appropriate agronomic packages will improve the adaptation of narbon bean to mediterranean-type environments of southern Australia. However, the adoption of narbon bean in Australian agriculture will depend on its marketability and acceptance by the stockfeed industry, and its on-farm utility.

Growth and seed yield of vetches (Vicia spp.) in south-western Australia

The growth and seed yield of 5 vetch (Vicia) cultivars representing Vicia sativa, V. benghalensis and V. villosa were compared at 8 sites over 2 years in south-western Australia. The vetches showed considerable potential as grain and forage legume crops in the low to medium rainfall areas of the Western Australian cereal belt. Cultivars of V. sativa showed the most potential in terms of dry matter and seed yield, and on average across sites and seasons both Languedoc and Blanchefleur produced over 2.5 t/ha of dry matter at flowering: Machine-harvested seed yields were over 1.6 t/ha. Cultivars of V. benghalensis and V. villosa produced considerably less dry matter at flowering and had lower harvest index (0.14-0.42) and seed yield < 4 t/ha) when compared with the V. sativa cultivars, possibly due to their poor growth rates and delayed phenology. Early Purple, an early flowering and maturing selection from the V. benghalensis cultivar Popany, showed improved adaptation and seed yield at many low rainfall sites. Nevertheless, Languedoc, Blanchefleur and Early Popany are all considered late flowering (up to 126 days) compared with grain legumes adapted to this environment, and further improvement in vetch species could be achieved by selecting for more rapid development. Both soft-seededness and non-shattering pods should also be high priorities for vetch selection and/or breeding programs. It is concluded that vetch species may have a role in farming systems in Western Australia for the production of fodder, hay, grain or green manure while providing the other rotational benefits of legumes on fine-textured neutral to alkaline and shallow duplex soils where narrow-leafed lupin is poorly adapted.

Growth, yield and neurotoxin (ODAP) concentration of three Lathyrus species in mediterranean-type environments of Western Australia

The growth, phenology, grain yield and neurotoxin (ODAP) content of Lathyrus sativus, L. cicera and L. ochrus were compared with a locally adapted field pea (Pisum sativum L.) to examine their potential as grain legumes in Western Australian farming systems. About 17 lines of each species were obtained from ICARDA, Syria, and grown at 3 agro-climatically different sites. In general, the 3 species were later flowering than field pea, especially L. cicera and L. ochrus; however, L. sativus was the last species to mature. The best Lathyrus lines produced biomass near flowering similar to field pea. At the most favourable site, grain yields were up to 1.6, 2.6 and 1.7 t/ha for L. sativus, L. cicera and L. ochrus respectively, compared with a field pea grain yield of 3.1 t/ha. There was considerable genotype and environmental variation in ODAP concentration in the seed. On average, the ODAP concentration of L. ochrus (6.58 mg/g) was about twice that of L. sativus, and L. cicera had the lowest ODAP concentration (1.31 mg/g). Given that Lathyrus spp. have not had the same breeding effort as field pea and other grain legumes in Australia, these results encourage further selection or breeding. In the shor-tseasoned, mediterranean-type environment of Western Australia, harvest indices and grain yields could be improved with early flowering. Low ODAP concentration should also be sought.

A comparison of seed yields of winter grain legumes in Western Australia

Field trials were conducted in 2 seasons at 13 sites on neutral to alkaline soils in Western Australia, to compare the growth and seed yield of 6 winter grain legume species: field pea (Pisum sativum L.), chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), lentil (Lens culinaris Medik), narrow leaf lupin (Lupinus angustifolius L.), albus lupin (L. albus). In a dry year (1991), overall site mean seed yield was highest for field pea (1.35 t/ha), then faba bean (1.22 t/ha) and narrow leaf lupin (0.85 t/ha). Chickpea, lentil line ILL5728, and albus lupin produced an average seed yield of 0.64 t/ha. Rainfall in 1992 was above average and seed yields of all species except field pea were higher than in 1991. Heavy rainfall in winter and spring caused transient waterlogging at several sites, affecting growth and seed yield of most species. Faba bean responded positively to the increase in rainfall and produced exceptional seed yields of >4 t/ha at 3 sites. Mean seed yield was highest for faba bean, at 2.87 t/ha, then narrow leaf lupin (1.19 t/ha), chickpea (1.1 t/ha), and field pea (1.0 t/ha). Field pea performed poorly at several sites due to its susceptibility to transient waterlogging and black spot disease (caused by Mycosphaerella pinoides). Albus lupin and lentil line ILL5728 produced similar seed yields (0.78 t/ha). Lentil cvv. Laird (1991) and Kye (1992) had low seed yields due to poor adaptation. Seed yield differences between species at various locations were not simply related to any soil chemical parameters or to depth to clay. On a calcareous soil of pH(CaC12) 8 at Dongara, the growth of narrow leaf lupin was severely affected and the crop failed. Days to flowering varied between species; faba bean was earliest to flower (76 days), then field pea. Faba bean and field pea (particularly in 1991) generally produced the most dry matter, both early and at final harvest. The relationship between seed yield and rainfall was complicated by transient waterlogging and fungal disease (e.g. black spot in field pea) at many sites. Seed yield was significantly positively related to final dry matter production but not to harvest index.

Early sowing with wheat cultivars of suitable maturity increases grain yield of spring wheat in a short season environment

Eleven field trials were sown in the northeastern wheatbelt of Western Australia to test the hypothesis that if wheat cultivars with suitable maturity are sown earlier than current practice, then higher grain yields will be achieved. The experiments included time of sowing treatments that ranged from early May to late June in 1988, 1989 and 1990. Seven commercial cultivars with a wide range of developmental patterns and maturities were used. Sowing between mid May and early June produced the highest grain yields. For plantings after early June, yields declined by approximately 250 kg/ha (15%) per week. Delayed sowing caused a decrease in dry matter and kernel number (per m2). In general this reduction in kernel number was not compensated by an improvement in kernel weight. At early times of sowing, the medium-long season cultivars generally had higher yields than short season cultivars. The short season cultivars were the highest yielding cultivars at the late times of sowing. These results suggest that cultivars should be chosen to suit the seasonal break, which may vary from late April to mid June. As a consequence, farmers should be encouraged to retain a number of cultivars with differing maturities suited to a range of planting times.

Potential for increasing early vigour and total biomass in spring wheat. II. Characteristics associated with early vigour

Increased early growth and total dry matter production have been suggested as useful traits to improve yield in Mediterranean-type environments. In Part I, genotypic variation for early growth and total dry matter production was identified among cultivars and some introduced lines. In this part, characteristics associated with early vigour in five of these introduced lines and ten Australian cultivars were examined in a field study at Wongan Hills in Western Australia. Differences in dry matter production were observed at all sampling times during the season, with three of the introduced lines (CEP 8058, Kansu No. 32 and V979-28) having consistently higher dry matter production than the standard cultivars during the early growth period. Those genotypes with a higher dry matter production at 54 days after sowing had higher relative growth rates and green area indices than those with low dry matter production. Both genotypes with large leaves on few tillers and genotypes with small leaves on many tillers had higher green area indices and higher dry matter production. While high dry matter production was associated with a large degree of ground cover and high light interception, it was not associated with the earlier commencement of reproductive development. Incorporation of early vigour and high dry matter production into locally adapted cultivars is required to demonstrate its benefit in these environments.

Crop growth and relative growth rates of old and modern wheat cultivars

An analysis of the dynamics of green area index (GAI), dry matter (DM), relative growth rate (RGR) and crop growth rate (CGR) based on growing degree days (GDD) is presented for a historical series of wheats commercially released in Western Australia. Relative to the old cultivars, modern wheats were characterized by a greater RGR during the vegetative phase. This was achieved at a lower initial GAI, which persisted as the season progressed and was associated with a higher CGR at anthesis and greater grain yield at the end of the season. In the old cultivars, a greater GAI during the mid season declined rapidly as temperatures and soil moisture stress increased in spring, resulting in a lower GAI at anthesis. Together with lower CGR at anthesis this resulted in less dry matter and grain yield at final harvest. The higher grain yield of modern wheat cultivars was achieved with a high RGR during the vegetative phase and greater CGR from ear emergence to harvest.

Water use and water use efficiency of old and modern wheat cultivars in a Mediterranean-type environment

Water use and water use efficiency of old and modern wheat cultivars and one barley cultivar were measured in a Mediterranean environment at Merredin, W.A. Water use efficiency for grain increased substantially from old to modern cultivars, with little difference among modern cultivars. Water use efficiency for dry matter was similar between cultivars. Barley had the highest water use efficiency of both grain and dry matter. Improved water use efficiency for grain in modern cultivars was associated with faster development, earlier flowering, improved canopy structure and higher harvest index. Modern cultivars used slightly less water than old cultivars. The pattern of water use was also different, with late-maturing old cultivars using more water in the pre- than the post-anthesis period. The ratio of pre- to post-anthesis water use was highest with the late-maturing, old cultivar Purple Straw (5.2:1) and lowest with early-maturing, modern cultivar Gutha (3.0:1). Soil evaporation estimates showed that modern cultivars had lower rates of soil evaporation in the early part of the growing season. This was associated with their faster leaf area development and improved light interception. About 40% of the total water use was lost by soil evaporation with very little difference between wheat cultivars. Barley had 15% less soil evaporation than wheat. Water use efficiency for grain based on transpiration (transpiration efficiency) for the four modern cultivars was 15.8 kg ha-1 mm-1, similar to other studies in comparable environments. Some further improvement in water use efficiency appears possible through improvement in crop biomass and harvest index. However, given the frequent and severe limitations of total water supply at low rainfall sites such as Merredin, there appears to be more scope for improvement in yield and water use efficiency in the medium and high rainfall areas of the wheatbelt.

Growth, development and light interception of old and modern wheat cultivars in a Mediterranean-type environment

A field experiment was conducted at Merredin in the eastern wheat belt of Western Australia, comparing 10 wheat cultivars representing old and modern wheats. The aim of the study was to identify any morphological and physiological characters associated with higher grain yield of modern wheat cultivars.The modern cultivars reached double ridge, terminal spikelet, anthesis and maturity earlier than the old cultivars, but modern cultivars had a longer duration between double ridge and terminal spikelet stage. The number of leaves on the main stem generally decreased from old, Purple Straw (14) to modern cultivars like Kulin (8). The modern cultivars had a shorter phyllochron interval than the old cultivars. The old cultivars also produced more tillers per plant (7.3) and had a lower percentage (35%) of ear bearing tillers, as compared with 3.9 and 51% for modern cultivars.The green area index and ground cover was higher in old than modern cultivars. However, the efficiency of conversion of photosynthetically active radiation to dry matter was slightly greater for modern cultivars. Although dry matter at final harvest was similar between cultivars, there was a trend for higher dry matter production with modern cultivars. The post-anthesis green area duration was longer with modern cultivars and grain yield increased with increase in post-anthesis green area duration.Grain yield and HI increased consistently from old to modern cultivars. The most recent cultivar Kulin had the highest yield and second highest harvest index, which were 63% and 48% respectively higher than the oldest cultivar, Purple Straw. Increases in grain yield in the modern cultivars were associated with increased grains spikelet-1 and grains ear-1. Mean grain weight showed a slight reduction with modern cultivars. The results are discussed in relation to future improvement in yield.

Canopy development modifies the water economy of chickpea (Cicer arietinum L.) in south-western Australia

Soil water balance and plant data from a time of sowing trial, and estimates of transpiration efficiency, were used to assess the importance of soil cover, provided by developing canopies, on the water use and its partitioning between soil evaporation and transpiration. As reported in an earlier paper, time of sowing strongly affected the timing and rate of canopy development, and had little effect within years on total water use, which was 221 mm in 1982 and 185 mm in 1983. Time of sowing also modified the pattern of water use, and this was reflected in substantial effects on the partitioning of water use, between soil evaporation and transpiration, and in turn on yield and water use efficiency. Estimated water use by soil evaporation ranged from 100 to 125 mm in 1982 and from 75 to 115 mm in 1983. The majority of this, an average of 80 mm, in 1982 and 75 mm, in 1983, occurred during the winter months, June to August, and varied mildly with soil cover. Soil cover had its greatest effect on water use through transpiration during spring, when temperatures were rising rapidly. Transpiration varied between sowing dates by 20 mm in 1982, and by 40 mm in 1983. Measures to improve water use efficiency should aim to reduce soil evaporation during winter both directly, by increasing soil cover, for example, by mulches or earlier-developing canopies, and indirectly by increasing infiltration. In spring, measures to improve water use efficiency should aim at reducing transpiration by minimising canopy development to what is required by the crop to maximise harvest index.

Chickpea (Cicer arietinum L.), a potential grain legume for South-Western Australia: Seasonal growth and yield

The suitability of chickpea (Cicer arietinum L.) as a winter-sown grain crop was evaluated for the Merredin region (310 mm rainfall) in the south-western Australian cereal belt. Few data on performance of chickpea were available from southern Australia, but similarities of the Merredin climate with that of Aleppo in Syria, where chickpea has been grown for centuries, indicated its potential. The response of a desi-type early line of chickpea was studied in a time of sowing by density trial in 1982 and a time of sowing trial in 1983, by relating seed and biological yield to dry matter accumulation and distribution, phenological and morphological development. Seed yields averaged 1.20 t ha-1 over the two years, and was little affected by time of sowing or density over the normal sowing period, and confirmed early flowering as the basic ideotype for the region. Seed yield correlated poorly with harvest index, but highly with biological yield within, but not between years. Time to flowering was fairly constant, averaging 100 days after 1160�C days, and flowering stopped soon after maximum LAI was reached. Detailed observations in 1983 showed that the efficiency of formation of seed bearing pods from flowers increased from 38% for the earliest planting to 83% in the latest planting. The failure of early sown chickpea to exploit the longer growing season resulted from the high abortion rate of early flowers, probably caused by low spring temperatures. The 35% of pods aborted in late spring, in all sowing dates, indicates that water stress can be expected to limit chickpea yields, as in other cultivated species, in the region. Chickpea demonstrated good yield potential for the drier cereal belt on heavy-textured soils at Merredin, to which medics are adapted. The data indicate scope to increase yields by improving tolerance to cold during early flowering and support the concept of increasing seed yields by restricting the number of branches at higher densities, as found in a previous study.