Genetic diversity, combining ability, heterosis and antioxidant enzymes of some rice genotypes under normal and water deficit.

Abstract

Five rice lines and three testers were crossed in line x tester mating design and the resultant fifteen hybrids along with their eight parents were evaluated under normal and drought conditions (irrigation every 12 days). This investigation was undertaken at the experimental farm of Rice Research and Training Center (RRTC), Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2019 and 2020 growing season. Genetic diversity, combining ability, heterosis, and antioxidant enzymes were studied. Four primers were used to study genetic diversity. The results revealed a total number of 7 alleles were ranged from one to three alleles per locus, the average of major allele frequency, gene diversity, and (PIC) were 0.607, 0.45, 0.46), respectively. The GD dendrogram revealed the close similarity among the genotypes; IET 1444, GZ1368 and G177 clustered together in the main cluster. On another hand, NP856-9 diverged in sub cluster and the other genotypes G178, G179, A22, and G182 were clustered together. The drought had an intensive inhibition on studied traits, plant height, chlorophyll content, grain yield plant-1 and 1000 grain weight. Otherwise, all genotypes were more earliness under drought than under normal. Highly significant differences were detected among genotypes and their partitions for all studied traits. Both additive and non-additive are important in the inheritance of studied traits. The parents GZ 1368 under normal irrigation and combined data and IET 1444 under stress condition seemed to be the best combiner for grain yield plant-1. The cross NP856-9 X GZ 182 revealed the highest significant and positive SCA effects for chlorophyll content and grain yield/plant. The most desirable midparent and better-parent heterosis for grain yield plant-1 were detected for the crosses IET1444 x G182 and NP856-9 x G182, respectively in the combined data. Results indicated that the activity of antioxidant enzymes: CAT, APX, SOD, and MDA enhanced under drought conditions. Similarly, proline accumulation increased due to water stress.

Genetic Behavior of Grain Yield and Quality Traits under Water Deficit and Normal Conditions of some Rice Genotypes

“…Meanwhile, the interaction between SCA X irrigation treatments was higher than of GCA X environment for all studied traits, revealing that non-additive gene action was more influenced by drought more than additive genetic variance. This result was in accordance with El-Badawy, et al, (2022).…”

“…of panicles/plant, panicle length and panicle weight under normal, drought and their combined data, which indicating that the predominance of additive genetic variance in controlling of these traits. These findings were previously reported by Gowayed, et al, (2020) and El-Badawy, et al, (2022). On the other hand, mean squares due to SCA were much higher than those of GCA for 1000-grain weight, grain yield plant -1 and fertility % under normal, drought and their combined analyses, revealing the importance of non-additive gene action in governing these traits.…”