Influence of Climate Change on Metabolism and Biological Characteristics in Perennial Woody Fruit Crops in the Mediterranean Environment

Orchard Microclimate Control as a Way to Prevent Kiwifruit Decline Syndrome Onset

A syndrome called "Kiwifruit Decline Syndrome" (KiDS) affects kiwifruit in several Mediterranean areas, causing growth arrest and wilt that rapidly progress to desiccation, scarce root growth, absence of fibrous roots, brown soft-rotting areas, and cortical detachment from the central cylinder. The origin is considered multifactorial, and a correlation with hydraulic conductance impairment caused by a high vapor pressure deficit (VPD) and temperature was detected. In this work, over-tree micro-sprinkler irrigation and shading nets were tested to protect leaves from overheating and locally decrease VPD. Leaf gas exchanges, leaf temperature, stem water potential, stem growth, root starch content, root xylem vessel diameter, density, and vulnerability to cavitation were assessed. A positive effect of over-tree irrigation associated with shading was observed: lower leaf temperature, higher stem water potential, stomatal conductance, and photosynthesis were detected; moreover, root starch content was higher in the summer. Narrow xylem vessel diameters were observed, indicating a long-term adaptation to rising VPD for lower vulnerability to cavitation, in all plants, but higher diameter, lower density, and higher vulnerability index indicated lower plant water stress under over-tree irrigation associated with shading. These results indicate that microclimate control by proper agronomic management can protect kiwifruit from climate stress, decreasing the risk of KiDS onset.

Spatio-temporal dynamics of root water uptake and identification of soil moisture thresholds for precision irrigation in a Mediterranean yellow-fleshed kiwifruit orchard

Introduction

Actinidia is highly susceptible to water stress, both excess and shortage, and is therefore a model fruit crop for irrigation management, requiring precise water application. The present study was carried out in a mature kiwifruit orchard in southern Italy to investigate the physiology of a yellow-fleshed kiwifruit cultivar under non-limiting soil water conditions and in response to a progressive decrease in soil water content in a Mediterranean environment, with the aim of defining soil moisture thresholds to guide irrigation management.

Methods

The progressive lowering in soil moisture was monitored using multi-profile probes, taking into account a 60 cm layer. Plant water status and physiological parameters were measured throughout the experiment and were significantly correlated with soil water status, suggesting that the level of soil water deficit affects plant physiological performance.

Results

Reference minimum values of stem water potential reached during the day under non-limiting soil water conditions ranged from -0.4 to -0.7 MPa, with a value of -0.8 MPa identifying the threshold below which stomatal conductance began to decrease significantly. Soil moisture thresholds were defined according to the spatio-temporal dynamics of available water (AW) reduction, which decreased by approx. 10% and 1% before the onset of water stress and 16% and 2% at the onset of water stress, considered in the 0-30 cm and 30-60 cm soil layers, respectively, compared to the AW content of the whole soil profile.

Discussion

Results confirmed that root uptake was mainly concentrated in the first 30 cm of soil depth, which should be properly managed by irrigation, as reduced soil water availability could easily lead to plant water stress. An integrated approach, combining plant measurements and soil water content monitoring, together with an assessment of root water uptake dynamics, is essential to identify soil water thresholds and develop precision irrigation, especially for high water-demanding crops and environments.

Nanostructure-assisted drought tolerance in olive trees (Olea europaea L.): the role of Fe2O3-graphitic carbon

Olive trees are known as one of the most iconic crops in the world. Considering the increasing water deficit worldwide, implementing some profitable and empirical strategies can be inevitable upon exposure to drought stress. Therefore, the present study aimed at clarifying the beneficial role of exogenously foliar application of Fe2O3 modified carbon nitride nanostructures (control, FeSO4, C3N4 and Fe2O3/g-C3N4) to "Shengeh" olive cultivars grown at different watering levels (100, 75, and 50% ET) in two experimental years (2022 and 2023) and the pomological attributes, physiological and biochemical changes happening in the treated leaves and fruits were discussed. The results indicated that drought stress caused a significant decline in pomological attributes in this experiment, and treatments could remarkably make up for this damage. Overall, Fe2O3/g-C3N4 outperformed as compared FeSO4 and C3N4 alone, which were also efficacious in conferring tolerance to the water deficit stress. Conversely, severe drought stressed-olive fruits showed higher oil content percent in the fresh matter and water use efficiency (WUE) in oil by 30% and 52.5%, respectively, as an average of results of two years, and after Fe2O3/g-C3N4, these features in olive plants subjected to severe drought improved by an average of 35% over two years. Ca2+ and K+ in olive plants under severe drought stress declined by 50% and 83% in 2022 and 46% and 24% in 2023, while Na+ increased in the plants exposed to 50%ET stress by 48% and 57% in two successive experimental years respectively. The application of Fe2O3/g-C3N4 remarkably improved the contents of Ca2+ and K+ by 101.5% and 369%, respectively, as an average of two years. Conversely, this beneficial treatment led to a significant decline in Na+ levels by 30% in 2022 and 2% in 2023 under stressful conditions. Moreover, it decreased the 'osmolytes' content, caused a smaller decline in chlorophyll levels, and resulted in higher relative water content occurring in the treated olive leaves. The reduction of oxidative markers was a result of the increased enzymatic activity after the use of Fe2O3/g-C3N4. Therefore, this treatment is a promising strategy to achieve improved resistance in olive plants in the future.

Climate Change Impacts on and Response Strategies for Kiwifruit Production: A Comprehensive Review

Climate change, a pressing global concern, poses significant challenges to agricultural systems worldwide. Among the myriad impacts of climate change, the cultivation of kiwifruit trees (Actinidia spp.) faces multifaceted challenges. In this review, we delve into the intricate effects of climate change on kiwifruit production, which span phenological shifts, distributional changes, physiological responses, and ecological interactions. Understanding these complexities is crucial for devising effective adaptation and mitigation strategies to safeguard kiwifruit production amidst climate variability. This review scrutinizes the influence of rising global temperatures, altered precipitation patterns, and a heightened frequency of extreme weather events on the regions where kiwifruits are cultivated. Additionally, it delves into the ramifications of changing climatic conditions on kiwifruit tree physiology, phenology, and susceptibility to pests and diseases. The economic and social repercussions of climate change on kiwifruit production, including yield losses, livelihood impacts, and market dynamics, are thoroughly examined. In response to these challenges, this review proposes tailored adaptation and mitigation strategies for kiwifruit cultivation. This includes breeding climate-resilient kiwifruit cultivars of the Actinidia species that could withstand drought and high temperatures. Additional measures would involve implementing sustainable farming practices like irrigation, mulching, rain shelters, and shade management, as well as conserving soil and water resources. Through an examination of the literature, this review showcases the existing innovative approaches for climate change adaptation in kiwifruit farming. It concludes with recommendations for future research directions aimed at promoting the sustainability and resilience of fruit production, particularly in the context of kiwifruit cultivation, amid a changing climate.

Response of photosynthetic characteristics and yield of grape to different CO2 concentrations in a greenhouse

Due to the enclosed environment of greenhouse grape production, the supply of CO2 required for photosynthesis is often insufficient, leading to photosynthetic downregulation and reduced yield. Currently, the optimal CO2 concentration for grape production in greenhouses is unknown, and the precise control of actual CO2 levels remains a challenge. This study aims to investigate the effects of different CO2 concentrations on the photosynthetic characteristics and yield of grapes, to validate the feasibility of a CO2 gas irrigation system, and to identify the optimal CO2 concentration for greenhouse grape production. In this study, a CO2 gas irrigation system combining CO2 enrichment and gas irrigation techniques was used with a 5-year-old Eurasian grape variety (Vitis vinifera L.) 'Flame Seedless.' Four CO2 concentration treatments were applied: 500 ppm (500 ± 30 µmol·mol-1), 700 ppm (700 ± 30 µmol·mol-1), 850 ppm (850 ± 30 µmol·mol-1), and 1,000 ppm (1,000 ± 30 µmol·mol-1). As CO2 concentration increased, chlorophyll a, chlorophyll b, and carotenoids in grape leaves all reached maximum values at 700 ppm and 850 ppm during the same irrigation cycle, while the chlorophyll a/b ratio was lower than at other concentrations. The net photosynthetic rate (Pn) and water use efficiency (WUE) of grape leaves were the highest at 700 ppm. The transpiration rate and stomatal conductance at 700 ppm and 850 ppm were significantly lower than those at other concentrations. The light saturation point and apparent quantum efficiency reached their maximum at 850 ppm, followed by 700 ppm. Additionally, the maximum net photosynthetic rate, carboxylation efficiency, electron transport rate, and activities of SOD, CAT, POD, PPO, and RuBisCO at 700 ppm were significantly higher than at other concentrations, with the highest yield recorded at 14.54 t·hm-2. However, when the CO2 concentration reached 1,000 ppm, both photosynthesis and yield declined to varying degrees. Under the experimental conditions, the optimal CO2 concentration for greenhouse grape production was 700 ppm, with excessive CO2 levels gradually inhibiting photosynthesis and yield. The results provide a theoretical basis for the future application of CO2 fertilization and gas irrigation techniques in controlled greenhouse grape production.

Lower soil nitrogen-oxide emissions associated with enhanced denitrification under replacing mineral fertilizer with manure in orchard soils

Emerging evidence suggests that replacing mineral fertilizers with organic livestock manure can effectively suppress reactive gaseous nitrogen (N) emissions from soils. However, the extent of this mitigation potential and the underlying microbial mechanisms in orchards remain unclear. To address this knowledge gap, we measured nitrous and nitric oxide (N2O and NO) emissions, microbial N cycling gene abundance, and N2O isotopomer ratios in pear and citrus orchards under three different fertilization regimes: no fertilization, mineral fertilizer, and manure plus mineral fertilizer. The results showed that although manure application caused large transient peaks of N2O, it reduced cumulative emissions of N2O and NO by an average of 20 % and 17 %, respectively, compared to the mineral fertilizer treatment. Partial replacement of mineral fertilizers with manure enhanced the contribution of AOA to nitrification and reduced the contribution of AOB, thus reducing N2O emissions from nitrification. Isotope analysis suggested that the pathway for N2O production in the soils of both orchards was dominated by bacterial denitrification and nitrifier denitrification. The manure treatment reduced the ratio of denitrification products. Additionally, the dual isotope mixing model results indicated that partially replacing mineral fertilizers with manure could promote soil denitrification, resulting in more N2O being reduced. N-oxide emissions were on average 67 % higher in the pear orchard than in the citrus orchard, probably due to the differences in soil physicochemical properties and growth habits between the two orchards. These findings underscore the potential of partially replacing mineral fertilizers with organic manure in orchards to reduce gaseous N emissions, contributing to the transition towards environmentally sustainable and climate-smart agricultural practices.

Open field hardening improves leaf physiological drought tolerance in young plants of Sindora siamensis

The effect of drought stress on leaf physiology was studied in 10-month-old plants of Sindora siamensis . Plants were either placed in an open greenhouse (unhardening; UH) or in an open field (open field hardening; H) for 45days. Both the UH and H plants stopped receiving water (D) until the initial drought injury and then rewatered (R) until complete recovery. Results showed necrosis in the leaves of UH+D, while H+D showed wilting at Day 7 after drought. A greater degree of necrosis was found in UH+D+R but made complete recovery in H+D+R at Day 4 after rewatering. Drought stress resulted in decreased leaf area in H, and reduced leaf and stem water status, PSII efficiency, net photosynthetic rate, stomatal conductance and transpiration rate in both UH and H. It also resulted in an increase in water use efficiency in both UH and H. Electrolyte leakage and malondialdehyde contents in UH were markedly increased due to drought stress. These results suggest that unhardened young plants of Sindora exposed to drought exhibited enhanced stomata behaviour by minimising open stomata and transpiration, resulting in high efficiency of water usage. However, there was still membrane damage from lipid peroxidation, which caused necrosis. Open field hardened plants exposed to drought demonstrated reduced open stomata and transpiration, thereby preserving leaf and soil water status and enhancing water use efficiency. This may be a reduction in lipid peroxidation though an oxidative scavenging mechanism that causes a slight alteration in membrane stability and a slight necrosis.

Influence of organic fertilization on growth and yield of strawberry (Fragaria × ananassa) in Kabete and Mbooni areas, Kenya

Strawberries are a valuable crop in Kenya with the potential for significant economic contributions. However, strawberry production in the country has been facing considerable challenges, impacting its economic potential. This study examined the influence of organic manure on strawberry growth and characteristics in Kabete and Mbooni areas in Kenya. The study used a randomized complete block design (RCBD) with three replications. Treatments included livestock manure (well composted mixture of chicken, goat, and cow manure), bokashi manure, and a control, coded as LivManure, BokManure and Control, respectively. Growth parameters including leaf area, number of white flowers and number of runners, as well as yield parameters such as the number and weight of strawberries were assessed from the 3rd to 10th week after transplanting, during the short rain season of 2021. Using R statistical software, linear models were fitted to datasets from both study sites and analyzed using one-way ANOVA, followed by post-hoc tests for multiple comparisons. The rigorous analysis of the Kabete and Mbooni datasets provided insightful revelations about the influence of different treatments on strawberry characteristics, and geographical disparities between the two regions. The analysis of variance (ANOVA) outcomes unveiled significant treatment effects in both sites, with F(2,69) = 62.57, p < 0.001 for Kabete and F(2,69) = 49.02, p < 0.001 for Mbooni, highlighting distinct influences of treatments on log values within each group. Post hoc analyses, including Tukey tests and bootstrap comparisons robustly validated the significant differences among the three treatments in each site, supported by p-values <0.001. Effect sizes were also employed to reinforce the findings, and planned contrasts were set to gain more power in the analysis of variance. Comparison between Kabete and Mbooni indicated a significant difference of 9.78 units, with Mbooni area exhibiting significantly higher strawberry characteristics compared to Kabete. The results showed that LivManure treatment had the highest mean in both sites, followed by BokManure and Control treatments, respectively. These findings have important implications for agriculture, and highlight the potential benefits of using LivManure treatment to improve strawberry characteristics in similar agroclimatic settings. These observations can be attributed to the beneficial effects of livestock manure on soil health, which include buffering of the soil reaction, provision of essential plant nutrients and enhancement of soil faunal activities. Balanced use of livestock manure is recommended to enhance soil macro and micronutrients, and soil reaction for improved growth and yield of strawberry.

Flavor profiling and gene expression studies of indigenous aromatic rice variety (Mushk Budiji) grown at different altitudes of Highland Himalayan regions

Mushk Budiji-an indigenous aromatic rice variety is usually grown at an altitude ranging from 5000 to 7000 ft above mean sea level in Highland Himalayas. This study was conducted to investigate the effects of altitude, soil nitrogen content and climatic conditions (temperature) of the selected locations on the flavor profile of Mushk Budiji using gas chromatography-mass spectroscopy (GC-MS) and electronic nose (E-nose). E-nose being rapid and non-destructive method was used to validate the results of volatile aromatic compounds obtained using GC-MS in Mushk Budiji. Around 35 aromatic compounds were identified in Mushk Budiji rice samples. Highest volatile peak area percentage (105.41%) was recorded for Mushk Budji grown at an altitude of 5216.53 ft. Highest E-nose score (2.52) was obtained at an altitude of 6299.21 ft. Over-expression of fatty acid degradation and linoleic acid metabolism genes was observed at higher altitudes, whereas lipid biosynthesis was negatively influenced by higher altitude. Fatty acid degradation and linoleic acid metabolism is responsible for the synthesis of volatile aromatic compounds in Mushk Budiji. This study will therefore be the path finder for investigating the intricate mechanism behind the role of altitude on aroma development in Mushk Budiji rice for future studies.

Impact of Climate Change on Altered Fruit Quality with Organoleptic, Health Benefit, and Nutritional Attributes

As a consequence of global climate change, acute water deficit conditions, soil salinity, and high temperature have been on the rise in their magnitude and frequency, which have been found to impact plant growth and development negatively. However, recent evidence suggests that many fruit plants that face moderate abiotic stresses can result in beneficial effects on the postharvest storage characters of the fruits. Salinity, drought, and high temperature conditions stimulate the synthesis of abscisic acid (ABA), and secondary metabolites, which are vital for fruit quality. The secondary metabolites like phenolic acids and anthocyanins that accumulate under abiotic stress conditions have antioxidant activity, and therefore, such fruits have health benefits too. It has been noticed that fruits accumulate more sugar and anthocyanins owing to upregulation of phenylpropanoid pathway enzymes. The novel information that has been generated thus far indicates that the growth environment during fruit development influences the quality components of the fruits. But the quality depends on the trade-offs between productivity, plant defense, and the frequency, duration, and intensity of stress. In this review, we capture the current knowledge of the irrigation practices for optimizing fruit production in arid and semiarid regions and enhancement in the quality of fruit with the application of exogenous ABA and identify gaps that exist in our understanding of fruit quality under abiotic stress conditions.

Modeling Phenological Phases across Olive Cultivars in the Mediterranean

Modeling phenological phases in a Mediterranean environment often implies tangible challenges to reconstructing regional trends over heterogenous areas using limited and scattered observations. The present investigation aimed to project phenological phases (i.e., sprouting, blooming, and pit hardening) for early and mid-late olive cultivars in the Mediterranean, comparing two phenological modeling approaches. Phenoflex is a rather integrated but data-demanding model, while a combined model of chill and anti-chill days and growing degree days (CAC_GDD) offers a more parsimonious and general approach in terms of data requirements for parameterization. We gathered phenological observations from nine experimental sites in Italy and temperature timeseries from the European Centre for Medium-Range Weather Forecasts, Reanalysis v5. The best performances of the CAC_GDD (RMSE: 4 days) and PhenoFlex models (RMSE: 5-9.5 days) were identified for the blooming and sprouting phases of mid-late cultivars, respectively. The CAC_GDD model was better suited to our experimental conditions for projecting pit hardening and blooming dates (correlation: 0.80 and 0.70, normalized RMSE: 0.6 and 0.8, normalized standard deviation: 0.9 and 1.0). The optimization of the principal parameters confirmed that the mid-late cultivars were more adaptable to thermal variability. The spatial distribution illustrated the near synchrony of blooming dates between the early and mid-late cultivars compared to other phases.

Exploring innovation adoption behavior for sustainable development of Mediterranean tree crops

Introduction

The combination of knowledge, personal skills and company resources influences, all things being equal, such as the availability of new technologies, market conditions and other factors external to the company, farmers in their innovation choices. This study is an attempt to understand which psychological constructs influence the decision-making process of farmers specialized in typical Mediterranean crops with regard to innovation. Previous studies on the adoption of agricultural innovations have often considered socio economic characteristics and ignored the underlying motivational factors that influence the behavioral intention of farmers.

Methods

This study adopted three socio-psychological constructs, Attitude (ATT), Subjective Norm (SN), and Perceived Behavioral Control (PBC), derived from the Theory of Planned Behavior (TPB), and proposed three new constructs, Perceived Innovations Characteristics (PIC), Benefits (B), and Transferability (T), thus using an Extended Model of the Theory of Planned Behavior.

Results

The outcome of the multiple regression revealed that farmers' intention (I) to adopt sustainable irrigation innovations is positively influenced by attitude (ATT), subjective norm (SN), and perceived innovation characteristics (PIC). This last construct had mediating effects on the indirect relationships between PBC, benefits (B), transferability (T), and intention (I).

Discussion

The results provide numerous insights, useful both for outlining the demand for innovation and for calibrating future policies aimed at the primary sector, especially on the sustainable management of irrigation resources. In particular, the analyses carried out highlight the importance of factors external to the company as key levers in shaping the demand for innovations.

Economic sustainability assessment of Mediterranean crops: A comparative Life Cycle Costing (LCC) analysis

The production of food with beneficial health effects is at the attention of consumer entrepreneurs and public decision-makers. Plants with established health benefits such as almonds, olives from which olive oil is made, and figs have always been cultivated in the Mediterranean basin. In the past, these three crops were widely cultivated in Italy, particularly in the southern part, where the best soil and climate conditions persisted. Today, however, almond and fig production is at an all-time low. The present study aims to assess the economic sustainability of investments in shell almond, olive, and fig farms by integrating Life Cycle Costing (LCC) methodology with specific economic indicators. In addition, a comparison between the three crops is made based on all economic results. The analysis allowed for the consideration of all costs over the entire life cycle of the investments, streamlining business decision-making for the choice between different alternatives. The results demonstrated greater economic profitability of investments in shelled almonds and dried figs and an adequate level of profitability. On the other hand, the results for olive trees were low. In this context, the production of almonds and figs could represent an important agribusiness chain, useful for the improvement of the rural economy.

The Biostimulant Effect of Hydroalcoholic Extracts of Sargassum spp. in Tomato Seedlings under Salt Stress

Currently, the use of biostimulants in agriculture is a tool for mitigating certain environmental stresses. Brown algae extracts have become one of the most important categories of biostimulants in agriculture, and are derived from the different uses and positive results obtained under optimal and stressful conditions. This study aimed to examine the efficacy of a foliar application of a hydroalcoholic extract of Sargassum spp. and two controls (a commercial product based on Ascophyllum nodosum and distilled water) with regard to growth, the antioxidant system, and the expression of defense genes in tomato seedlings grown in nonsaline (0 mM NaCl) and saline (100 mM NaCl) conditions. In general, the results show that the Sargassum extract increased the growth of the seedlings at the end of the experiment (7.80%) compared to the control; however, under saline conditions, it did not modify the growth. The Sargassum extract increased the diameter of the stem at the end of the experiment in unstressed conditions by 14.85% compared to its control and in stressful conditions by 16.04% compared to its control. Regarding the accumulation of total fresh biomass under unstressed conditions, the Sargassum extract increased it by 19.25% compared to its control, and the accumulation of total dry biomass increased it by 18.11% compared to its control. Under saline conditions, the total of fresh and dry biomass did not change. Enzymatic and nonenzymatic antioxidants increased with NaCl stress and the application of algal products (Sargassum and A. nodosum), which was positively related to the expression of the defense genes evaluated. Our results indicate that the use of the hydroalcoholic extract of Sargassum spp. modulated different physiological, metabolic, and molecular processes in tomato seedlings, with possible synergistic effects that increased tolerance to salinity.