In order to evaluate genetic parameters and drought tolerance indices using multivariate analysis, seventeen genotypes of rice were evaluated under normal and drought conditions. The combined analysis of variance indicated highly significant effects of genotype on all studied traits under normal and drought conditions. Most studied genotypes were better than the grand mean during normal and drought conditions. Drought stress reduced the studied traits while other was tolerant to drought, suggesting genetic variability in these genotypes for drought tolerance. The environmental and genetic variances and heritability showed highly significant for all studied traits under normal and drought conditions. The maximum values of genetic variance were found for all studied traits followed by the environmental and genotypes × season variances at normal and drought conditions. High heritability coupled with high genetic advance as percent of the mean was observed for most studied traits under normal and drought conditions. The differences between phenotypic coefficients of variation (PCV%) were higher than the values of genotypic coefficients of variation (GCV%) for all

Twenty-one hybrids developed from crossing seven lines and three testers were assessed for the extent of combining ability effects, heterosis and genetic parameters for yield and related contributing traits. The analysis of variance uncovered that there were highly significant differences for all the studied traits except panicle weight among parents and parents vs. crosses. The two promising lines GZ 9461-4-2-3-1 and GZ 1368-S-5-4 were seen as a good general combiner among lines for most of the traits, while among the testers, the parental variety Sakha S 300 was superior. Two crosses out of hybrids, GZ 9461-4-2-3-1 / Milyang 349 and GZ 1368-S-5-4 / IR14K642 exhibited positive and highly significant SCA effects for grain yield plant -1 , respectively. The maximum positive and highly significant mid-parent heterosis and heterobeltiosis for grain yield plant -1 were observed. The five crosses GZ 1368-S-5-4 / Sakha S 300, GZ 1368-S-5-4 / IR14K642, GZ 9461-4-2-3-1 / Milyang 349, GZ 9461-4-2-3-1 / Sakha S 300 and GZ 9461-4-2-3-1 / IR14K642 recorded the highest values and maybe extensively used in rice programs by adopting a heterosis breeding strategy. The additive gene action was noticed for days to 50% flowering, plant height, flag leaf area, number of panicles plant -1 , panicle length, panicle weight, panicle density index, spikelets fertility, 1000-grain weight, and grain yield plant -1 . Grain yield plant -1 was highly significantly and positively correlated with plant height, flag leaf area, number of panicles plant -1 , panicle weight and panicle density index indicating the significance of these traits as determination criteria in yield enhancement.

Salinity is a major abiotic constraint faced by farmers in many rice-growing regions of the world and improving grain yield in rice is the most important breeding objective. Thirty-five crosses were generated in a line x tester mating design by crossing seven lines with five testers and were evaluated in a randomized complete block design at the greenhouse lysimeter of Rice Research Department, Sakha, Kafr El-Sheikh, Egypt, during the two rice-growing seasons of May, 2021 and 2022. Analysis of variance revealed a highly significant difference among testers and lines for all the studied traits. Variances of specific combining ability were higher in magnitude than the corresponding general combining ability. The lines Sakha 107, Sakha 104, and Giza 182 including testers SAL 010, and CSR 28 were the best general combiners for grain yield plant -1 under saline conditions. The variety Giza 179 followed by Sakha 107 was the best general combiner for 100-grain weight under both normal and saline conditions. Two crosses Giza 179/MTU 1010 and Sakha 107/SAL 010 exhibited highly significant positive estimates of specific combining effects for grain yield plant -1 , respectively. Estimates of narrow sense heritability for all the traits under study were low which indicated a preponderance of non-additive gene action governing these traits. By selecting the appropriate genotypes and phenotypes, the outcomes will be beneficial in breeding salt-tolerant cultivars at both the seedling and reproductive stages.

A new rice variety takes about 12 years to release, the number of available distinct morphological features is very small, due to the continual pressure of releasing new varieties. The objectives of this study were: to estimate the genetic variation of Egyptian japonica, indica, and indica/japonica genotypes, and to identify, DNA fingerprinting with employing simple sequence repeat (SSR) markers to develop DNA barcode. This study includes 15 rice genotypes that were genetically evaluated using 32 microsatellites. DNA barcodes as well as the unique pattern of SSR polymorphism were produced. A total of 116 alleles was detected and the number of alleles ranged from 2 to 5, with an average of 3.625 alleles per locus. The polymorphism information content (PIC) introduced a mean of 0.566 and there was a positive correlation between the highest value of PIC and the highest number of detected alleles by SSRs. The principal coordinate analysis, specifically, PC1 and PC2, explained 54.72% and 12.96% of the total variability, respectively, for the 32 SSR. One set of multiplex assay with five markers each (RM307, RM317, RM470, RM412 and RM242) was developed for all the 15 rice genotypes. The findings revealed that increasing genetic diversity in the national rice breeding programme requires introducing germplasm from other places with various genetic backgrounds. Furthermore, the identification, DNA barcode approach and certification of genotypes utilizing microsatellite markers could be a decent supplement to existing agro-morphological features when genotypes are firmly related.