Antioxidant status and their enhancements strategies for water stress tolerance in chickpea

Morpho-Physiological Traits and Oil Quality in Drought-Tolerant Raphanus sativus L. Used for Biofuel Production

Raphanus sativus L. is a potential source of raw material for biodiesel fuel due to the high oil content in its grains. In Brazil, this species is cultivated in the low rainfall off-season, which limits the productivity of the crop. The present study investigated the effects of water restriction on the physiological and biochemical responses, production components, and oil quality of R. sativus at different development stages. The treatments consisted of 100% water replacement (control), 66%, and 33% of field capacity during the phenological stages of vegetative growth, flowering, and grain filling. We evaluated characteristics of water relations, gas exchange, chlorophyll a fluorescence, chloroplast pigment, proline, and sugar content. The production components and chemical properties of the oil were also determined at the end of the harvest cycle. Drought tolerance of R. sativus was found to be mediated primarily during the vegetative growth stage by changes in photosynthetic metabolism, stability of photochemical efficiency, increased proline concentrations, and maintenance of tissue hydration. Grain filling was most sensitive to water limitation and showed a reduction in yield and oil content. However, the chemical composition of the oil was not altered by the water deficit. Our data suggest that R. sativus is a drought-tolerant species.

Screening and Selection of Drought-Tolerant High-Yielding Chickpea Genotypes Based on Physio-Biochemical Selection Indices and Yield Trials

Chickpea production is seriously hampered by drought stress, which could be a great threat in the future for food security in developing countries. The present investigation aimed to screen the drought-tolerant response of forty desi chickpea genotypes against drought stress through various physio-biochemical selection indices and yield-attributing traits. Principle component-based biplot analysis recognized PG205, JG2016-44, JG63, and JG24 as tolerant genotypes based on physiological selection indices. These genotypes retained higher relative water content, stomatal conductance, internal CO₂ concentration, and photosynthetic rate. ICC4958, JG11, JAKI9218, JG16, JG63, and PG205 were selected as tolerant genotypes based on biochemical selection indices. These genotypes sustained higher chlorophyll, sugar and proline content with enhanced antioxidant enzyme activities. With respect to yield trials, JAKI9218, JG11, JG16, and ICC4958 had higher seed yield per plant, numbers of pods, and biological yield per plant. Finally, JG11, JAKI9218, ICC4958, JG16, JG63, and PG205 were selected as tolerant genotypes based on cumulative physio-biochemical selection indices and yield response. These identified drought-tolerant genotypes may be further employed in climate-smart chickpea breeding programs for sustainable production under a changing climate scenario.

Zinc Nanoparticles (ZnNPs): High-Fidelity Amelioration in Turnip (Brassica rapa L.) Production under Drought Stress

The detrimental effects of drought have adverse impacts on the crop yield as global climatic changes put unusual pressure on water resources. The challenge of attaining water security is key for the sustainable development of crops. Zinc (Zn2+) is an important nutrient that helps to alleviate drought stress by modulating the growth and yield of crops. Recently, zinc nanoparticles (ZnNPs) have been used as a novel strategy for the fertilization of crops. This study was specifically developed to observe the comparative effects of ZnNPs and conventional zinc sulfate (ZnSO4) at diverse concentration levels (0.01%, 0.05%, and 0.1%) that could effectively decrease the injurious effect of drought stress on turnip plants. In experiments on the golden turnip variety, drought stress caused a significant reduction in all growth and biochemical attributes, and increased antioxidant enzymatic activity. In a comparison with the conventional fertilizer ZnSO4, the foliar application of 0.1% ZnNPs significantly improved plant height, biomass, root/turnip length, turnip diameter, antioxidant defense system, secondary metabolites, and photosynthetic pigments in the leaves under drought stress. Based on the collected results, it is suggested that the foliar application of ZnNPs, instead of ZnSO4, under drought stress is helpful in increasing the growth and yield of turnip plants.

Alternate gene expression profiling of monoterpenes in Hymenocrater longiflorus as a novel pharmaceutical plant under water deficit

Hymenocrater longiflorus (surahalala) is a wild plant species with potential pharmaceutical and ornamental interest. To date, the genomics of this plant is unknown and the gene expression profiling of the genes related to its metabolite has never been studied before. In order to study the responses of in vitro-grown surahalala plants to abiotic stresses and the differential expression of the genes related to its essential oils under exogenous proline application; three levels of PEG600 (0, 10, and 20%) and five levels of proline (0, 5, 10, 15, and 20 µm) were combined in the culture media. Thus, water deficit increased oxidants levels and decreased fresh weight of surahalala tissues, whereas addition of proline up to 15 µm was able to relatively compensate the negative effect of water deficit. Contrarily, high proline level (20 µm) had a negative effect on surahalala plants probably due to the stress simulation (nutrition) under high proline concentration. In addition, the best combination for achieving highest essential oils content was 10 µm proline plus 10% PEG. The expressional profiling of the genes TPS27, L3H, TPS2, TPS1, OMT and GDH3 were successfully carried out and their involvement in 1,8-cineole, carvone, α-pinene, thymol, estragole and β-Citronellol biosynthesis, respectively, was verified. In addition, our results indicated that these genes could also be involved in the synthesis of other metabolites under water deficit condition.