Rice is the world’s largest food crop, and its production needs to be doubled by 2050 to cope with population growth and associated demand. In addition to the value of improving yields, quality is also important for breeders and consumers, but it pays less attention in arid regions. During two successive summer growing seasons, the experimental material focused on 34 genotypes developed from different crosses on Fn generation after fixation as well as six of the most recent commercial cultivars used for comparisons. The results showed that a high yield of grain followed by high milling and grain quality characteristics were observed among the 34 genotypes used in this analysis. Highly important and positive correlations between the percentage of hulling and the percentage of milling (0.424) and the yield ability could be accomplished by choosing the number of panicles per plant and the weight of the panicles. Selection criteria for good quality should be met by the percentage of head rice and many mineral elements, particularly zinc and iron. As a consequence, the genotypes M.J 5460S/SK105-1, M.J 5460S/GZ7768-1, M.J 5460S/G177-1, M.J 5460S/SK105-3 and M.J 5460S/SK106-4 had desirable high yield and quality characteristics and could be used as promising accessions to the rice breeding program in arid regions. In addition to commercial genotypes, improved Japonica rice genotypes could be produced in arid conditions for higher yield and quality, leading to an increase in total production, supporting food security and nutrition.

his study was carried out during the period from 2016 to 2018 summer seasons in the open field at Kaha Vegetable Research Farm (KVRF), Kalubia, Egypt. Thirty local inbred lines of melon (Cucumis melo var. ananas) were evaluated in this investigation during 2016 and 2017 summer seasons in the open field to determine their mean performance. Based on the former evaluation, 12 inbred lines (RIL A2, RIL A3, RIL A7, RIL A8, RIL A14, RIL A18, RIL A19, RIL A22, RIL A23, RIL A26, RIL A29, RIL A30) and 3 testers (RIL A5, RIL A10 and RIL A20) were selected to determine their genetic performance using line × tester mating design during 2018 summer season. Thirty six crosses in one direction were conducted in the plastic house of Kaha Vegetable Research Farm, Kalubia through the 2017 late summer season. The 36 hybrids were evaluated along with their parents to determine heterosis, combining ability and heritability of leaf area index (LAI), yield components, average fruit weight, netting percentage, fruit shape index (FSI), seed cavity diameter, flesh thickness and total soluble solids (TSS). The genotype results showed highly significant mean squares for most of the studied traits. Inbred lines (female parents), Testers (male parents) and Line x Tester interaction showed highly significant differences of almost whole traits. Some crosses revealed highly significant and significant mid-parent and better-parent heterosis for many of the traits. The inbred line RIL A5 (T5) showed higher positive general combining ability (GCA) impact for all traits except early yield and FSI, which could be used as parent in breeding programs and the potential parent (good combiner) that in selection program would be effective for its efficient use in subsequent crossing programs for more LAI, total yield, marketable yield percentage, average fruit weight, netting percentage, flesh thickness, TSS and less seed cavity diameter. Nine, eight, twelve and seven hybrids revealed highly significant and significant specific combining ability (SCA) impacts of early yield, total yield, average fruit weight and TSS, respectively. The best specific combining ability (SCA) was observed in hybrids RIL A29 × RIL A5 for early yield, RIL A19 × RIL A20 for total yield and RIL A8 × RIL A10 for average fruit weight and TSS. The results confirmed the presence of genetic differences among the genotypes (female and male parents) and heterosis of crosses indicating the existence of predominance of nonadditive gene action in genetic control of the studied traits.

Cytoplasmic male sterility (CMS) provides an irreplaceable strategy for commercial exploitation of heterosis and producing high-yielding hybrid rice. The exogenous application of plant growth regulators could improve outcrossing rates of the CMS lines by affecting floral traits and accordingly increase hybrid rice seed production. The present study aimed at exploring the impact of growth regulators such as gibberellic acid (GA3), indole-3-acetic acid (IAA), and naphthalene acetic acid (NAA) on promoting floral traits and outcrossing rates in diverse rice CMS lines and improving hybrid rice seed production. The impact of foliar applications of growth regulators comprising GA3 at 300 g/ha or GA3 at 150 g/ha + IAA at 50 g/ha + NAA at 200 g/ha versus untreated control was investigated on floral, growth, and yield traits of five diverse CMS lines. The exogenously sprayed growth regulators, in particular, the combination of GA3, IAA, and NAA (T3) boosted all studied floral, growth, and yield traits in all tested CMS lines. Moreover, the evaluated CMS lines exhibited significant differences in all measured floral traits. L2, L3, and L1 displayed the uppermost spikelet opening angle, duration of spikelet opening, total stigma length, style length, stigma brush, and stigma width. In addition, these CMS lines exhibited the highest plant growth and yield traits, particularly under T3. Consequently, exogenous application of GA3, IAA, and NAA could be exploited to improve the floral, growth, and yield traits of promising CMS lines such as L2, L3, and L1, hence increasing outcrossing rates and hybrid rice seed production.

Rice is considered a strategic crop for many countries around the world, being the main cash crop for farmers. Water shortage stress occurrence as a result of climate change is among the main threats challenging rice breeders in the last few decades. In the current study, 19 Fn-lines were developed from four populations by crossing a reverse thermo-responsive genic male sterile (rTGMS) line, M.J.5460S, with the three high-quality Egyptian commercial cultivars Giza177, Sakha105, Sakha106 and the promising line GZ7768 as male parents. These newly developed lines, along with their parents, and two water shortage stress-tolerant international genotypes (Azucena and IRAT170), were cultivated under water-shortage stress conditions and compared with their performance under well-watered conditions. Results indicated that the yielding ability of the 19 newly developed lines exceeded those for the two Egyptian parents (Giza177 and Sakha105) under well-watered conditions. The lines M.J5460S/GIZA177-3 and M.J5460S/GIZA177-12 were the best performing genotypes under water shortage stress conditions. The genetic and heritability in broad sense estimates indicated that direct selection for grain yield (GY) under water-shortage stress is highly effective in the current study. Molecular marker analysis revealed that M.J5460S/GIZA177-3 had accumulated the quantitative trait loci (QTL)s, on the chromosomes 2, 3, and 9, which contribute to GY under water-shortage stress from their high yielding tolerant ancestor, M.J5460S. It could be concluded that those lines are high yielding under both well-watered and water-stress conditions harboring several QTLs for yield enhancement under both conditions and that the markers RM555, RM14551, RM3199, RM257, RM242, and RM410 are among the markers that could be used in marker-assisted selection (MAS) breeding programs for such stress condition.

Deficit irrigation (DI) is a choice made by producers to improve water productivity and might be highly preferred in future production programs in arid regions. Identifying DI-tolerant cultivars will be critical to improve rice (Oryza sativa L.) productivity under the future climate change conditions. Nuclear magnetic resonance (NMR)-based metabolomics is a recent technique that has received less attention so far and can be used to compare genetic differences in DI tolerance. For this purpose, field experiments were carried out during two successive summer seasons in Egypt to compare genetic differences for water deficit tolerance in seven rice genotypes using NMR technique. The genotypes Azucena and IRAT 170 achieved the best values of water productivity (WP) under DI, recording 1.79 and 0.99 kg m -3 respectively, confirming their suitability in the water deficit breeding program to produce new promising lines and to keep yield potential stable under climate change conditions. The PLS-DA of 1H-NMR spectra showed a clear separation between genotypes under both full irrigation (FI) and DI conditions. Quantitative analysis showed that sucrose, threonine, glutamate, and allantoin were accumulated at DI when compared to FI conditions, and these metabolite compounds may be closely related to DI conditions. Tryptophan, as an aromatic amino acid, has increased across cultivars, most dramatically in Azucena and IRAT 170. Tyrosine and phenylalanine also increased in Azucena and IRAT 170, but not as dramatically as tryptophan. The rice genotypes Azucena and IRAT 170 could be successfully recommended for higher yields and quality under DI conditions.