Deficit irrigation water (DW) is one of the main stress factors that negatively affect cotton cultivation. Hence, the identification of cotton cultivars tolerant to DW and sandy soil conditions is particularly needed. Understanding the response of cultivars to DW is essential for estimating water needs. Besides, by understanding the physiological and antioxidant status, reflecting distinct growth, yield, and fiber quality traits under DW, the cultivar tolerant to DW can be identified in the early stage of plant growth. Therefore, two cotton cultivars (Giza 86 and Giza 92, selected for their suitability to the climatic conditions of the study area) were evaluated in this study under two DW regimes (80% or 60% of crop evapotranspiration; ETc) vs. complete irrigation water (CW; 100% of ETc as a control). These regimes amounted to 1228 or 922 vs. 1536 mm season−1, respectively, for field trials conducted during the 2019 and 2020 summer seasons. DW (80% or 60% of ETc) significantly decreased relative water content, membrane stability index, chlorophyll content, plant height, yield components, and fiber quality traits. Otherwise, phenolic compounds, proline contents, as well as antioxidant enzyme activities increased in concomitance with an increase in electrolyte leakage and malondialdehyde content. The harmful effects of the higher DW (60% of ETc) were more pronounced in both cultivars. However, compared to Giza 86, Giza 92 showed higher performance under both CW and DW regimes, accounting for higher values for all studied traits in the blooming stage. The correlation coefficient showed that most of the physiological traits and antioxidants under study were effective criteria in identifying a high-yielding cultivar under DW in the cotton blooming stage and therefore can be used to select the cotton cultivar more suitable for the conditions of the study area. Biplot analysis was used to study the relationship between DW and all evaluated traits, as it was found that the most prominent traits were elongation (%) with Giza 92 + 100% ETc, yellowness degree with Giza 86 + 100% ETc, and SOD with Giza 92 + 60% ETc.

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Drought is a major abiotic stress that greatly affects canola growth, production, and quality. Moreover, water scarcity is projected to be more severe and frequent as a result of climate change, in particular in arid environments. Thereupon, developing drought-tolerant and high-yielding canola genotypes has become more critical to sustaining its production and ensuring global food security with the continuing population growth. In the present study, ten canola genotypes comprising six developed tissue-cultured canola genotypes, two exotic genotypes, and two commercial cultivars were evaluated under four irrigation regimes. The applied irrigation regimes were well-watered (100% crop evapotranspiration, ETc), mild drought (80% ETc), moderate drought (60% ETc), and severe drought (40% ETc) conditions. Drought-stress treatments (80, 60, and 40% ETc) gradually reduced the chlorophyll content, relative water content, flowering time, days to maturity, plant height, number of pods, number of branches, seed yield, and oil percentage, and increased proline, phenolic, anthocyanin, and glycine betaine contents. The evaluated genotypes exhibited varied responses to drought-stress conditions. The developed tissue-cultured genotypes T2, T3, and T1, as well as exotic genotype Torpe, possessed the highest performance in all evaluated parameters and surpassed the other tested genotypes under water-deficit conditions. Overall, our findings elicited the superiority of certain newly developed tissue-cultured genotypes and exotic ones compared with commercial cultivars, which could be exploited in canola breeding under water-deficit conditions.

Lentil is one of the essential legume crops, which provides protein for humans and animals. This legume can improve soil fertility through nitrogen fixation, which is imperative in low-fertility soils. The growth and productivity of lentil could be enhanced through improving nutrition and root revitalization. Therefore, the objective of this study was to assess the impact of root activator (RA) and phosphorus (P) application on morphological, physiological, agronomic, and quality traits of lentil under newly reclaimed low-fertility sandy soil in an arid environment. The RA was applied at four levels of 0 (RA0-untreated control), 1.25 (RA1), 2.5 (RA2), and 3.75 (RA3) l ha–1. RA contained 9% potassium humate, 1,600 ppm indole butyric acid, 200 ppm gibberellic acid, and 200 ppm naphthalene acetic acid. The recommended rate of phosphorus (P) fertilization in the newly reclaimed low-fertility sandy soil (75 kg P2O5 ha–1) was applied, and its amount was increased and decreased by 25 kg P2O5 ha–1 vs. non-added control. Thus, P rates were applied at four rates 0 (P0; control), 50 (P1), 75 (P2), and 100 (P3) kg phosphorus pentoxide (P2O5) ha–1. Our results revealed that treated lentil plants with the high levels of both treatments (RA3 and P3) exhibited superiority in root measurements (root length, total number of nodules plant−1, number of active nodules plant−1, dry weights of active nodules, and total root), nitrogenase activity, chlorophyll a and b, carotenoids, yield traits, and seed proteins and carbohydrates. However, the recommended P level (75 kg P2O5 ha–1, P2) under the high level of RA (3.75 l ha–1, RA3) displayed non-significant differences in yield traits (plant height, 1,000-seed weight, seed yield ha–1) and quality traits (protein and carbohydrate) with the high P level (100 kg P2O5 ha–1, P3). Accordingly, its recommended economically and environmentally to use this coapplication of RA3 and P3 in low-fertility soil for better lentil growth, and seed yield and quality.

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