Soil flooding severely impairs agricultural crop production. Plants can cope with flooding conditions by embracing an orchestrated set of morphological adaptations and physiological adjustments that are regulated by the elaborated hormonal signaling network. The most prominent of these hormones is ethylene, which has been firmly established as a critical signal in flooding tolerance. ABA (abscisic acid) is also known as a “stress hormone” that modulates various responses to abiotic stresses; however, its role in flooding tolerance remains much less established. Here, we discuss the progress made in the elucidation of morphological adaptations regulated by ABA and its crosstalk with other phytohormones under flooding conditions in model plants and agriculturally important crops.

Fertilization with high levels of phosphorus increases the risk of environmental pollution. Identification of critical values of P in soil (SOP) and in plant tissues (PiP) is essential for achieving the maximum wheat yield without P loss. The critical value is the value of P which gives the optimum yield; the response of crop yield to P fertilization above this value is not predictable or nil. Here, a 4-year field experiment was conducted to identify the SOP and PiP for achieving maximum yield of bread wheat using 11 rates of P fertilization (0, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 kg P2O5 ha-1). The linear–linear and Mitscherlich exponential models were employed to estimate the PiP and SOP. The degree of phosphorus saturation (DPS) was used to assess the potential environmental risk; furthermore, phosphorus use efficiency (PUE)was also calculated under the studied fertilization levels. Phosphorus in soil and wheat plant was affected by the application rates and growing seasons. Increasing P fertilization rates led to gradual increases in soil and plant P. The SOP ranged between 21 and 32 mg kg?1, while the PiP ranged between 6.40 and 7.49 g kg?1. The critical values of P calculated from the Mitscherlich exponential models were 20% higher than those calculated from the linear–linear models. Adding levels of P fertilization 90 kg P2O5 ha?1 leads to higher potentials of P runoff and leaching, in addition, PUE decreased sharply under high P fertilization levels. The response of wheat yield to P fertilization in sandy calcareous soil is predictable below Olsen P values of 21 mg kg?1. Identification of critical P values for wheat production is of great importance to help policy makers improve P use efficiency and attain optimum wheat yield under eco-friendly environmental conditions by eliminating the accumulation of excess P fertilizers in soil and water.

Soil salinity is one of the constraints of crop production in Egypt. The aims of this study were to identify genomic regions associated with grain weight and its related traits along with their salinity tolerance indices and to identify the most salinity tolerant and high-yielding genotypes. Therefore, we evaluated an advanced backcross mapping population of barley in newly reclaimed soil under two salinity levels of groundwater aquifers in South of Sinai, Egypt. We detected significant QTL associated with grain weight related attributes and the salinity tolerance index (STI) distributed throughout the whole genome of barley, which can be used to enhance salinity tolerance. Moreover, the markers bPb-3739 (4H, 96.3 cM), AF043094A (5H, 156 cM), bPb-8161 (7H, 2.22 cM), and bPb-5260 (7H, 115.6 cM), were the most important identified genomic regions corresponding to vernalization, dwarfing and dehydrin genes, which are correlated with salinity tolerance. Additionally, the doubled haploid lines SI001, SI043, SI044, SI028, SI242, SI035, and SI005 had the highest STI values based on yield average. The present study demonstrated that wild and elite barley do harbor novel valuable alleles, which can enrich the genetic basis of cultivated barley and improve quantitative agronomic traits under salinity conditions.

Twenty-one cultivars of bread wheat were evaluated for drought-stress tolerance at seedling ‎and maturity stages under non-drought and drought-stress conditions. Significant differences among ‎genotypes were obtained under non-drought and drought-stress conditions for all seedling and ‎maturity characteristics. Highly positive and significant correlations were found for root length with ‎respect to fresh weight of 0.74 and dry weight seedling of 0.80. However, negative and highly ‎significant correlations were found for both drought susceptible index based on seedling traits ‎‎(DSIST) and maturity traits (DSIST) with all seedling traits except root: shoot ratio, whereas no ‎correlations were obtained for either DSIST or DSIMT with all maturity traits except 1000 kernel ‎weight. Positive and highly significant correlation found between DSIST and DSIMT (0.85). SSR ‎markers analysis showed that three bands produced by Xgwm596-7A (507 bp), Xgwm497-1A (556 ‎bp) and Xgwm174-5D (409 bp), they were presented in all tolerant genotypes based on DSIST. The ‎three bands (507, 556 and 409 bp) were correlated to DSIST, with R2 values of 81.05%, whereas the ‎three bands were correlated to DSIMT with R2 values of 61.96%. Strong association was observed for ‎genotypic distance with phenotypic distance based on seedling characteristics, that amounted to ‎‎0.66, whereas the correlation was less strong between genotypic distance and phenotypic distance ‎based on maturity traits by 0.30. The seedling traits at 15% PEG were more association than maturity ‎traits under drought-stress with SSR markers, this gives preference to using seedling traits as an indicator of drought-stress tolerance in breeding programs.

The current research aimed to evaluate and select bread wheat stable cultivars with high ‎productivity across diverse sowing dates. Fourteen wheat cultivars were grown in a randomized ‎complete block design with three replicates at six sowing dates during two successive seasons of ‎‎2018/2019 and 2019/2020 representing twelve environments. The cultivars were evaluated for grain ‎yield and its attributes. Highly significant differences were obtained among the wheat cultivars, ‎sowing dates, and their respective interaction for all measured traits. The highest grain yield (2.992-ton ‎fed-1) was recorded on 30th November, after this date, each day delay in sowing of wheat onward ‎decreases grain yield at the rate of 21 kg fed-1 day-1. Overall, the cultivar Gemiza 11 gave the highest ‎grain yield with an average of 2.861 ton fed-1, recorded the highest 1000-GW with an average of 47.73 g, ‎highest straw yield with an average of 8.303-ton Fed-1, and was the earliest cultivar with a mean heading ‎date of 92.9 days. According to GGE biplot results, Gemiza 11, Gemiza 9, and Sakha 94 ranked in the ‎first order as high-yielding cultivars and had greater stability level overall sowing dates under ‎Assiut conditions. The most adequate cultivars for sowing in the first half of November (1st -15th ) ‎are Misr 2, Sids 12, Sakha 95, Gemiza 9, and Gemiza 11. Also, Sakha 94, Gemiza 9, and Gemiza 11 ‎can be sown after 30th November because they produce a satisfied yield, have good stability, and ‎can be considered as late sowing tolerant.‎

The present study was conducted at district Kom Ombo sugar cane farms, (latitude of 24o 28o N and longitude of 32o 57o E), Aswan Governorate, in the two seasons of 2015/2016 and 2016/2017 including plant cane and 1st ratoon crops, respectively. To study the effect of harvesting age and phosphorus fertilization levels on yield and quality of some sugar cane varieties. Field experiment included twenty-seven treatments represented the combinations among three harvesting ages (10, 11 and 12 months) three phosphorus fertilization levels [30, 45 and 60 kg P2O5/fad.] and three sugar cane varieties [G.T. 54-9, G.2003-47 and G.2004-27]. Randomized complete block design with three replications laind aut in split-split plots arrangement.