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Background: Water scarcity is responsible for losses in the yield of many plants and this is expected to continue due to climate change. However, cowpea which is known for its drought tolerance, is considered as a plant without limitations to climate change. A two-year experiment was conducted to evaluate the effect of water restriction on phenolic compounds, antioxidant capacity and leaf nutrients concentration of four cultivars of cowpea at different growth stages. At second leaf stage, two irrigation regimes were initiated (Water irrigation was applied after 75% and 55% of field capacity, as well watered and drought stress treatment, respectively).Plants samples were collectedat three stages(immature pod, immature seed and dry seed stage) for total phenol and flavonoids content, ortho-diphenols andantioxidant capacity measurement and leaves sampling for nutrients concentration. Results: The results indicated that polyphenolic compounds and antioxidant capacity increased under drought conditions. However, in both irrigation regimes, immature pods had the higher polyphenolic compounds, antioxidant capacity and leaf nutrients concentration rather than immature seeds and dry seeds. Among the genotypes, ILC482 revealed the highest content of total phenolics and ortho-diphenols (6.9 and 3.57 mg GA g−1dry weight, respectively). In addition, nitrogen, phosphorus and magnesium concentration of leaves were higher in ILC482 genotype. Under drought stress, ILC482 maintained higher ABTS radical scavenging capacity (0.0083 mmol Trolox g−1dry weight) compared to other genotypes. Conclusions: It is suggested that drought stress affect the quality of cowpea productions through polyphenolic compounds, ABTS and DPPH radical scavenging capacity which can be used as a helpful strategy to save water in the regions where water is scare. [ABSTRACT FROM AUTHOR]

Î' two-year field experiment was conducted in Varamin-Pishva Branch, Islamic Azad University, Iran to study the impact of drought stress and foliar application of some hormones on the safflower growth. The drought stress was induced at three levels and considered as main plots. Irrigating after 75% water depletion was considered to be normal irrigation (control), irrigating after 60 and 45% water depletion, defined as mild and severe drought stress, respectively. The foliar application of humic acid (HA), salicylic acid (SA), Gibberellic acid (GA3), ascorbic acid (AA), water, and the non-foliar application was considered as sub-plots. The main effect of irrigation regimes was significant on seed yield, oil yield, palmitic acid, and water use efficiency (WUE). Also, the main effect of foliar applications was significant for seed yield, oil yield, stearic acid, and WUE. Normal irrigation produced the maximum oil yield (2270 kg ha-1) that was decreased by 25.9% and 37.1% under mild and severe stress regimes, respectively. The maximum and minimum oil yields were produced by the application of SA and non-foliar treatment with average values 1970 and 1357 kg ha-1, respectively. Although the palmitic acid content was enhanced under the drought stress conditions, oleic acid content was significantly decreased in such conditions. The current findings suggest that the foliar application of SA can be recommended when optimal water supply was applied to increase the quality and quantity of safflower oilseed. [ABSTRACT FROM AUTHOR]

Finding methods, which may improve corn (Zea mays L.) growth and physiology under drought stress, is of significance. Accordingly, the effects of different plant growth regulators (PGRs) including benzyl adenine (BA6), gibberellins (GA 3+7), proline (Pr), and BA6 + GA 3+7 + Pr (sub plots), at different drought levels including control (S1), moderate (S2) and severe (S3) (main plots) on the physiology and genetic contents of corn (Single Cross 704) plants were investigated. A two-year field research, as a split plot on the basis of a randomized complete block design with four replications, was conducted in the Research Field of Islamic Azad University, Isfahan, Iran in 2015–2016. Corn physiological parameters including carotenoids (Car), total chlorophyll (Chlt), chlorophyll a (Chla), chlorophyll b (Chlb), plasma membrane resistance (PR), and rab17 expression were determined. Analysis of variance and comparison of means indicated the experimental treatments significantly (P ≤ 0.01) affected the measured parameters. The combination of PGRs and drought stress was not significant on PR, and just drought stress had a significant effect on rab17 expression at P ≤ 0.01. The year parameter significantly affected corn Car and PR. Although stress decreased plant Car, and Chl contents, it increased PR. The tested PGRs significantly improved corn physiology and rab17 expression, and interestingly their effectiveness enhanced with increasing the level of stress (significant interaction of PGRs and drought stress). The role of proline as an RNA binding protein affecting RNA activity and rab17 expression and subsequent corn tolerance under drought stress has been suggested. • Plant growth regulators (PGRs) affecting corn physiology and genetic under drought. • Proline and its combination with benzyl adenine and gibberellins the most effective. • Suggesting proline as and RNA binding protein in the alleviation of drought stress. • The possibility of alleviating drought stress in corn plants using the tested PGRs. [ABSTRACT FROM AUTHOR]