Water-deficit stress poses tremendous constraints to sustainable agriculture, particularly under abrupt climate change. Hence, it is crucial to find eco-friendly approaches to ameliorate drought tolerance, especially for sensitive crops such as maize. This study aimed at assessing the impact of seed halo-priming on seedling vigor, grain yield, and water use efficiency of maize under various irrigation regimes. Laboratory trials evaluated the influence of seed halo-priming using two concentrations of sodium chloride solution, 4000 and 8000 ppm NaCl, versus unprimed seeds on seed germination and seedling vigor parameters. Field trials investigated the impact of halo-priming treatments on maize yield and water use efficiency (WUE) under four irrigation regimes comprising excessive (120% of estimated crop evapotranspiration, ETc), normal (100% ETc), and deficit (80 and 60% ETc) irrigation regimes. Over-irrigation by 20% did not produce significantly more grain yield but considerably reduced WUE. Deficit irrigation (80 and 60%ETc) gradually reduced grain yield and its attributes. Halo-priming treatments, particularly 4000 ppm NaCl, improved uniformity and germination speed, increased germination percentage and germination index, and produced more vigorous seedlings with heavier dry weight compared with unprimed seeds. Under field conditions, the plants originated from halo-primed seeds, especially with 4000 ppm NaCl, had higher grain yield and WUE compared with unprimed seeds under deficit irrigation regimes. The long-lasting stress memory induced by seed halo-priming, particularly with 4000 ppm NaCl, promoted maize seedling establishment, grain yield, and WUE and consequently mitigated the devastating impacts of drought stress.

Water shortage is a major environmental stress that destructively impacts maize production, particularly in arid regions. Therefore, improving irrigation management and increasing productivity per unit of water applied are needed, especially under the rising temperature and precipitation fluctuations induced by climate change. Laboratory and field trials were carried out in the present study, which were aimed at assessing the possibility of promoting maize germination, growth, grain yield and crop water productivity (CWP) using seed priming under different irrigation regimes. Two seed priming treatments, i.e., hydro-priming and hardening versus unprimed seeds, were applied under four irrigation regimes, i.e., 120, 100, 80 and 60% of estimated crop evapotranspiration (ETc). The obtained results indicated that increasing irrigation water from 100% up to 120% ETc did not significantly increase grain yield or contributing traits, while it decreased CWP. Deficit irrigation of 80 and 60% ETc gradually decreased grain yield and all attributed traits. Seed priming significantly ameliorated seedlings’ vigor as indicated by earlier germination, higher germination percentage, longer roots and shoots, and heavier fresh and dry weight than unprimed seeds with the superiority of hardening treatment. Additionally, under field conditions, seed priming significantly increased grain yield, yield contributing traits and CWP compared with unprimed treatment. Interestingly, the results reflect the role of seed priming, particularly hardening, in mitigating negative impacts of drought stress and enhancing maize growth, grain yield and attributed traits as well as CWP under deficit irrigation conditions. This was demonstrated by a significant increase in grain yield and CWP under moderate drought and severe drought conditions compared with unprimed treatment. These results highlight that efficient irrigation management and seed priming can increase maize yield and water productivity in arid environments.

Due to their beneficial, stimulating impact on plant growth, productivity, and alleviating environmental stresses, protein hydrolysates have recently received increasing attention as a possible substitute. This investigation aimed to explore the effects of foliar application of papain-produced whey protein hydrolysates (WPH) on the yield attributes and nitrogen use efficiency (NUE) of soft wheat. Wheat plants were cultivated under a Mediterranean arid environment and received four soil nitrogen (N) fertilization levels with ammonium nitrate (145, 185, 215, and 250 kg N ha−1) and compared to control treatment and urea foliar application. WPH increased grain yield, yield attributes, and N accumulation in wheat plants. Partial productivity factors of applied nitrogen, as NUE indicators under relatively steady-state cropping systems, were also enhanced by WPH compared to control treatment. WPH significantly improved flag leaf area, spike number m−2, and grain yield compared to urea foliar application. Increasing the soil N fertilization level from 145 up to 215 kg N ha−1 was accompanied by significant increases in all yield traits and N accumulation measurements, except for the partial factor productivity of applied N, which decreased. A strong positive association was detected among grain and straw yields, their attributes, and total N uptake. Results highlighted the efficacy of WPH in increasing wheat yield and NUE.

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The study aims at evaluating humic acid application and nitrogen fertilization treatments viz., control, nitrogen foliar application (4%), 30 kg N fad -1 , 30 kg N fad -1 + N foliar application (4%) and 60 kg N fad -1 on productivity, grain quality and nitrogen use efficiency (NUE) of three barley varieties. In addition, the yield analysis of the three barley varieties viz., Giza129, Giza131 and Giza135 was investigated. Humic acid application enhanced barley productivity, quality and NUE. Giza131 surpassed the other two varieties in grain yield, some components and NUE in both seasons except protein content. Raising N level up to 60 kg Nfad -1 had a significant impact on all studied traits compared with control treatment, except NUE. Co-application of 30 kg N fad -1 +N foliar application improved barley yield, most of its attributes, grain quality and NUE, which reflect the efficacy of N foliar application in fulfilling barley nitrogen requirements with the soil N applications. Additionally, path analysis indicated that: the grain number spike -1 had the highest direct effect on the grain yield among the varieties Giza129 and Giza131, the highest indirect effects on grain yield were assigned for grain weight spike -1 and spike number m -2 , while spike numberm -2 had the greatest direct effect on the yield of Giza135, which demonstrates the importance of these traits in improving barley grain yield.