Selenium (Se) has been recently reported to play a crucial role in ameliorating the negative impact of abiotic stress, including salinity, on several plant species. Two field experiments (2016/17 and 2017/18) were carried out to investigate the possible effect of exogenous Se application at two levels (25, 50 mg L⁻¹) on growth, bulb yield, physio-biochemical attributes, and antioxidant activities of onion grown under saline (5.25 dS m⁻¹) soil condition. Se (25 or 50 mg L⁻¹) foliar application enhanced growth characteristics, as well as membrane stability index (MSI) and relative water content (RWC) as a result of the osmotic adjustment by accumulating more osmoprotectants and enhancing the activity of antioxidants defense system, thus improving photosynthetic efficiency and bulb yield. Proline, glycine betaine, choline, and total soluble sugars content were higher in leaves and bulbs of Se-treated plants under salt stress. Se (25 or 50 mg L⁻¹) significantly increased the activities of enzymatic (ascorbate peroxidase, superoxide dismutase, and catalase) and non-enzymatic (ascorbic acid and glutathione) antioxidants in both leaves and bulbs of salt-stressed onion. Se application at 25–50 mg L⁻¹ may find, in the future, a potential application as anti-abiotic stresses for improving plant growth and productivity under saline soil condition.

Sustainability of rice production under flooding conditions has been challenged by water shortage and food demand. Applying higher nitrogen fertilization could be a practical solution to alleviate the deleterious effects of water stress on lowland rice (Oryza sativa L.) in semi-arid conditions. For this purpose, field experiments were conducted during the summer of 2017 and 2018 seasons. These trials were conducted as split-split based on randomized complete blocks design with soil moisture regimes at three levels (120, 100 and 80% of crop evapotranspiration (ETc), nitrogen fertilizers at two levels (N₁—165 and N₂—200 kg N ha⁻¹) and three lowland Egyptian rice varieties [V₁ (Giza₁₇₈), V₂ (Giza₁₇₇) and V₃ (Sakha₁₀₄)] using three replications. For all varieties, growth (plant height, tillers No, effective tillers no), water status ((relative water content RWC, and membrane stability index, MSI), physiological responses (chlorophyll fluorescence, Relative chlorophyll content (SPAD), and yield were significantly increased with higher addition of nitrogen fertilizer under all water regimes. Variety V₁ produced the highest grain yield compared to other varieties and the increases were 38% and 15% compared with V₂ and V₃, respectively. Increasing nitrogen up to 200 kg N ha⁻¹ (N₂) resulted in an increase in grain and straw yields by 12.7 and 18.2%, respectively, compared with N₁. The highest irrigation water productivity (IWP) was recorded under I₂ (0.89 kg m⁻³) compared to (0.83 kg m⁻³) and (0.82 kg m⁻³) for I₁ and I₃, respectively. Therefore, the new applied agro-management practice (deficit irrigation and higher nitrogen fertilizer) effectively saved irrigation water input by 50–60% when compared with the traditional cultivation method (flooding system). Hence, the new proposed innovative method for rice cultivation could be a promising strategy for enhancing the sustainability of rice production under water shortage conditions.

Two field trials were conducted during the 2014/2015 and 2015/2016 seasons at Aweesh Al-Hagar Village, center of Mansoura, Dakahlia Governorate, Egypt. A split-split-plot design with four replicates was used. The main plots were assigned three nitrogen fertilizer levels, i.e., 165, 220, and 275 kg/ha. The sub-plots were restricted to four gibberellic acid (GA₃) concentrations, i.e., 0, 80, 160, and 240 mg/L, and the sub-sub plots received GA₃ application twice, i.e., 60 and 120 days after planting (DAP). The results showed that both root length and diameter, root and foliage fresh weights/plant, and root and foliage yields/ha increased with the incremental level of nitrogen and/or GA₃ concentration. Foliar application of GA₃ and N-fertilizers also significantly decreased quality parameters including sucrose and total soluble solid (TSS) percentages. Early application of GA₃ (60 DAP) had an active role on sugar beet growth, yield, and quality compared with spraying at 120 DAP. Generally, fertilizing sugar beet with 275 kg N/ha or spraying GA₃ with a concentration of 160 mg/L at 60 DAP is the recommended treatment for raising sugar yield under the ecological circumstances of this research.

Salinity is one of the most limiting abiotic stresses in agricultural productivity. Exogenously applied antioxidants successfully enabled salt-stressed plants to cope with stress. Two-season field experiments were conducted consecutively in 2016/17 and 2017/18 to study the effects of foliar applications of singular (ascorbate, AsA; proline, Pro; and glutathione, GSH) or sequential (AsA-Pro-GSH and GSH-Pro-AsA) antioxidants on growth, yield, physio-biochemical attributes, and enzymatic and non-enzymatic antioxidative defense system of Vicia faba L. (CV. Sakha-1) plants grown under saline soil conditions (EC = 4.53 dS m⁻¹). Under soil salinity conditions, AsA, Pro, or GSH-Pro-ASA improved growth and productivity, photosynthesis efficiency, stomatal conductance (gs), plant water status, as well as enzymatic and non-enzymatic antioxidants. However, sequential AsA-Pro-GSH foliar application followed by singular GSH significantly exceeded all other treatments (i.e., AsA, Pro, and GSH-Pro-AsA), improving growth characteristics (shoot length, shoot fresh and dry weights, and leaves area), photosynthesis efficiency, stomatal conductance, plant water status, and yield and its components (green pods weight/plant⁻¹, green pods yield/hectare⁻¹, and seed yield/hectare⁻¹), as well as enzymatic (ascorbate peroxidase, catalase, superoxide dismutase, and glutathione reductase) and non-enzymatic (AsA, GSH, Pro, phenolic aglycone, phenolic glycosides) antioxidants compared to control. Overall, our results clearly demonstrate that sequential AsA-Pro-GSH foliar application has a positive effect on salt-stressed Vicia faba plants.

Peanut (Arachis hypogaea L.) is commonly grown on sandy soils that are susceptible to water deficits. Because symbiotic nitrogen fixation in other grain legumes is especially sensitive to soil drying, the sensitivity of peanut nitrogen fixation to water deficits might be an important limitation on peanut production. This greenhouse study was undertaken to observe the response of nitrogen fixation (acetylene reduction) in six peanut cultivars to soil drying. In contrast to other grain legumes, peanut nitrogen fixation was relatively insensitive to soil drying. Acetylene reduction rates did not begin to decrease until soil water deficits had decreased to where leaf gas exchange was affected. These data indicated that restricted nitrogen fixation during drought stress is not likely to be a serious problem in peanut. Nevertheless, cultivar variation in drought sensitivity was identified indicating that genetic selection might further decrease the susceptibility of peanut nitrogen fixation to drought.