Worldwide periods of heat and drought are projected to be more frequent, longer, and occurring earlier, which could deleteriously affect the productivity of cool-season crops including wheat (Triticum spp.). The coexistence of heat and drought stresses affects plant biochemical and physiological processes including cell membrane function. The increased permeability and leakage of ions out of the cell has been used as a measure of cell membrane stability (CMS) and as a screen test for stress tolerance. The main objectives of this research were to: (1) screen a global spring wheat panel for CMS by exposing leaf tissue to heat treatment and osmotic pressure (PEG 600), (2) identify potential quantitative trait loci (QTL)/genes linked with CMS using genome-wide association mapping, and (3) estimate the relationship between the field performance and measured CMS. The results indicated highly significant differences among the 2111 spring wheat accessions regarding CMS. Moreover, several SNPs were found to be significantly linked with CMS. The annotation of the significant SNPs indicated that most of these SNPs are linked with important functional genes, which control solute transport through the cell membrane and other plant biochemical activities related to abiotic stress tolerance. Overall, this study demonstrated the use of genome-wide association mapping for the identification of potentially new genomic regions associated with CMS. Tolerant genotypes identified in this study proved to be more productive under preliminary field stress conditions. Thus, the identified membrane-stable accessions could be used as parental genotypes in breeding programs for heat or drought stress tolerance.

Stripe rust (incited by Puccinia striiformis f. sp. tritici) is airborne wheat (Triticum aestivum L.) disease with dynamic virulence evolution. Thus, anticipatory and continued screening in hotspot regions is crucial to identify new pathotypes and integrate new resistance resources to prevent potential disease epidemics. A global wheat panel consisting of 882 landraces and 912 improved accessions was evaluated in two locations in Egypt during 2016 and 2017. Five prevalent and aggressive pathotypes of stripe rust were used to inoculate the accessions during the two growing seasons and two locations under field conditions. The objectives were to evaluate the panel for stripe rust resistance at the adult plant stage, identify potentially novel QTLs associated with stripe rust resistance, and validate previously reported stripe rust QTLs under the Egyptian conditions. The results indicated that 42 landraces and 140 improved accessions were resistant to stripe rust. Moreover, 24 SNPs were associated with stripe rust resistance and were within 18 wheat functional genes. Four of these genes were involved in several plant defense mechanisms. The number of favorable alleles, based upon the associated SNPs, was significant and negatively correlated with stripe rust resistance score, i.e., as the number of resistances alleles increased the observed resistance increased. In conclusion, generating new stripe rust phenotypic information on this panel while using the publicly available molecular marker data, contributed to identifying potentially novel QTLs associated with stripe rust and validated 17 of the previously reported QTLs in one of the global hotspots for stripe rust.

Sustaining wheat production under low-input conditions through development and identifying genotypes with enhanced nutritional quality are two current concerns of wheat breeders. Wheat grain total protein content, to no small extent, determines the economic and nutritive value of wheat. Therefore, the objectives of this study are to identify accessions with high and low grain protein content (GPC) under well-watered and water-deficit growth conditions and to locate genomic regions that contribute to GPC accumulation. Spring wheat grains obtained from 2111 accessions that were grown under well-watered and water-deficit conditions were assessed for GPC using near-infrared spectroscopy (NIR). Results indicated significant influences of moisture, genotype, and genotype × environment interaction on the GPC accumulation. Furthermore, genotypes exhibited a wide range of variation for GPC, indicating the presence of high levels of genetic variability among the studied accessions. Around 366 (166 with high GPC and 200 with low GPC) wheat genotypes performed relatively the same across environments, which implies that GPC accumulation in these genotypes was less responsive to water deficit. Genome-wide association mapping results indicated that seven single nucleotide polymorphism (SNPs) were linked with GPC under well-watered growth conditions, while another six SNPs were linked with GPC under water-deficit conditions only. Moreover, 10 SNPs were linked with GPC under both well-watered and water-deficit conditions. These results emphasize the importance of using diverse, worldwide germplasm to dissect the genetic architecture of GPC in wheat and identify accessions that might be potential parents for high GPC in wheat breeding programs.

Breeding for drought tolerance is the most effective approach to mitigate drought effects. The prime goal of the current study was to identify potentially drought‐tolerant wheat (Triticum aestivum L.) genotypes. Therefore, an extensive collection of wheat genotypes (2,100) was evaluated under two water regimes, that is water deficit (WD, 50% ETc ‘crop Evapotranspiration’) and well‐watered (WW, 100% of ETc) across several environments in Egypt. The number of days to flowering (NDF), plant height (PH) and grain yield (GY) were recorded under both water regimes across environments. Additionally, three yield‐based drought indices and water‐use efficiency (WUE) were calculated for the top 30% yielding genotypes (that produced economical GY; 3.58 ton ha−1 for WD and 7.5 ton ha−1 for WW). The results indicated a significant effect for environments, water stress, and genotypes, as well as the second‐ and third‐order interactions across all traits. WD significantly reduced PH, NDF, and GY by 5.0 cm, 10.6 days and 50.0%, respectively. PH, NDF and GY were highly correlated. However, the direction and magnitude of correlation under normal conditions were different from those under WD. For example, under WW conditions, late flowering and taller genotypes tended to produce higher GY. In contrast, under WD, earlier and shorter wheat genotypes tended to produce higher GY. According to the drought tolerance index (DTI), 254 genotypes were considered drought tolerance (DTI > 1). Based on WUE, DTI and GY under WD, 80 genotypes outperformed the commercially grown Egyptian cultivars. Our results implied that the evaluated collection might be a valuable source not only for drought‐tolerant genotypes but also for highly yielding water‐efficient genotypes under favourable conditions in Egypt and similar geographic regions.

The International Maize and Wheat Improvement Center (CIMMYT) has identified the wheat (Triticum aestivum L.) irrigated area in the developing countries, which includes Egypt as Mega‐environment 1 (ME1). Agriculture intensification is expected to take place in this region to keep up with a continuously growing population, which might lead to more N application and losses because of the low N use efficiency (NUE) observed in this area. A panel of 40 wheat accessions including 10 commercially grown cultivars (CGCs), 10 elite lines from the CIMMYT, and 20 landraces from Egypt and Ethiopia were evaluated for grain yield (GY), grain protein content (GPC), NUE, agronomic NUE (AGNUE), stem rust, leaf rust, plant height (PH), leaf area, and total chlorophyll content (TCC), under four N levels. The panel was planted in two growing seasons (i.e., 2015–2016 and 2016–2017) and two locations. The results indicated that most of the CGCs were considered N efficient and N responsive. On the other hand, most landraces were N inefficient and nonresponsive because they produced higher GPC, PH, and TCC but had lower GY, AGNUE, and NUE. Furthermore, the landraces were less sensitive to the excessive N supply. ‘Sakha 94’, a commercially grown cultivar, was the most N efficient and N responsive; hence, it produced the highest GY at all N levels. The overall results might be scaled up to cover other Mediterranean basin regions that have similar environmental conditions.

Wheat (Triticum aestivum L.) uptakes only 40 to 60% of the soil available nitrogen. Sulfur deficiencies depress both nitrate uptake and nitrate reductase activity resulting in low nitrogen use efficiency. Soil and foliar supplied sulfur in combinations with foliar nitrogen were used on three of the modern and commercially grown wheat cultivars. The experiment was conducted in two consecutive growing seasons; 2017 and 2018 in a high pH soil, 8.55. Our results indicated that 714 kg ha-1 of pre-planting sulfur (SS) and spraying twice with 6.66% urea and 2.2% micronized sulfur (S1FS1N1) during stages 13 & 41 on Zadok`s scale, increased grain yield, total protein content, straw yield and plant height by 31.58, 26.09, 18.37 and 7.9% respectively. The results indicated a significant and positive impact sulfur-nitrogen combinations when applied on top of pre-planting applied sulfur. However, foliar sprayed sulfur had a more substantial effect on all traits, compared to the pre-planting sulfur or the foliar sprayed N, suggesting interference effect of the alkaline soil with the amount of sulfur recovered from the soil. When N and S foliar were applied simultaneously, a more substantial increase in grain yield, plant height, straw yield and total protein content was observed, suggesting a synergistic effect between these two elements. We attributed the positive effect of S1FS1N1 on improving photosynthates translocation from the sources to sinks. In addition to improving nitrogen use efficiency while reducing the plant content of NO−3 by optimizing the S/N ratio and reducing sulfur deficiency. Based on our results, we concluded that the foliar application of micronized S has the potential to improve the overall performance of wheat plants. Thus, we recommend enriching nitrogen and phosphate fertilizers with sulfur for alkaline soils.

In the current study, 248 two-rowed and another 253 six-rowed spring barley (Hordeum vulgare L.) breeding lines from several US barley breeding programs were evaluated in multiple locations in Egypt to select for potentially adapted lines. The introduced plant materials were planted in two locations during three growing seasons (2015, 2016, and 2017). The focus of the first growing season was to increase available seeds and collect preliminary observations. During the second and third growing seasons, the advanced plant materials and local check cultivars were planted in an incomplete block design in two replicates within three locations. Grain yield, leaf rust, number of days to flowering, and plant height were measured. Based on grain yield production, the top 94 lines from the two-rowed and 100 from the six-rowed barley lines were selected and advanced for further evaluation in 2017. The introduced materials contained several lines that consistently outperformed the check cultivars. Therefore, these lines could be used as parents to improve barley production and enhance genetic diversity or be directly released as cultivars after appropriate testing in Egypt.

Due to the high environmental risks of chemical pesticides, biological control of plant pests with bio-pesticides is highly encouraged and recommended. Chitosan and oligochitosan are well-known biological control agents for their nontoxic, biodegradable, and biocompatible properties. A field experiment was conducted at Nubaria Research Station during the 2020/2021 and 2021/2022 growing seasons to study the effect of different applications of chitosan on barley plants against aphid infestation under field artificial infestation conditions as well as yield and physiologic related traits. The experiment was laid out in a randomized complete block design (RCBD) with three replications and seven treatments among spraying, soaking, and combinations between them at two concentrations 250 and 500 mg. The study results revealed that there were significant variations among the seven treatments for all studied traits. The highest mortality percent was obtained from the treatment T7 (soaking seeds & spraying with 500 mg/L.), which was 99.5 % compared with untreated 2.66%; this treatment induced an increase in the thickness of grains and stem tissues, which caused a reduction in the feeding of aphids, resulting in a clear drop in population number. Significant increases were recorded for total phenolic content, protein content, yield and its components in T7 and T5 treatments.