Diallel Analysis of Different Rice Genotypes under Water Deficiency Conditions and Assessing Genetic Diversity Using SSR Markers

Abstract

A half diallel cross among seven diverse rice genotypes was carried out in 2019 growing season. Parents and their 21 F1 crosses were evaluated under normal (continuous flooding) and water deficit (irrigation every 12 days) conditions during 2020 growing season, to estimate general (GCA) and specific (SCA) combining ability effects as well as identifying type of gene action controlling the inheritance of the studied traits.Both GCA and SCA mean squares were highly significant for all the studied traits under normal and stress conditions. The non-additive gene action played an important role in the inheritance of all the studied traits, except leaf rolling under stress treatment. The parents Sakha 107, NERICA 9 and N22 were the best general combiners for grain yield/plant. The crosses Sakha 107×Giza 177, Sakha 107×Fuknishiki, NERICA 9×Giza 177, NERICA 9×Akihikari, N22 ×IET1444, N22×Fuknishiki and IET1444 × Giza 177 were identified as promising specific combiners for improving grain yield/plant and one or more of its components under both conditions. The genetic diversity among the seven parental genotypes was assessed using ten Simple Sequence Repeats (SSR) markers. A total of 33 alleles were detected ranging from 2 to 5 with an average of 3.3 alleles per locus. The PIC values ranged from 0.32 to 0.69, with an average of 0.51.Genetic distance ranged from 0.24 to 0.92 with an average of 0.63. High genetic diversity was detected among the tested genotypes at the molecular level, hence these genotypes could be exploited to improve water deficit tolerance in rice breeding program.

Molecular Genetic Diversity and Combining Ability for Some Physiological and Agronomic Traits in Rice under Well-Watered and Water-Deficit Conditions

“…Consequently, these parents could transfer their promising alleles to progenies and enhance grain yield under water-stress conditions. Previous studies have also emphasized the significance of using exotic and local parents with positive and high GCA effects for boosting grain yield and related agronomic traits under normal and water-deficit conditions [ 3 , 17 , 21 , 72 ].…”

“…The selection of parental genotypes with good GCA effects and offspring with high SCA effects for eligible traits can be thereby enhanced. Several studies have exploited GCA and SCA to recognize good parents and identify the best crosses for improving stress tolerance in rice [ 3 , 17 , 18 , 19 , 20 , 21 ].…”

Developing Novel Rice Genotypes Harboring Specific QTL Alleles Associated with High Grain Yield under Water Shortage Stress

“…This negative effect was previously reported by [ 14 , 22 ], as the stress caused severe reduction in plant height, biomass, spikelet fertility, and GY. Water shortage stress pushes plants to perform more respiration and reduce photosynthesis, leading to less biomass accumulation and less GY [ 32 , 33 ].…”

“…Multiple earlier investigations reported yield reductions of more than 50%, confirming successful water stress screening [ 3 , 18 ]. Poor panicle weight, length, seed set, 1000-grain weight, and seed set are some of the causes of GY reduction under water-stress [ 32 , 34 ]. The current investigation results confirm the ability to use GY under water-shortage as an effective direct selection criterion for enhancing water-shortage stress tolerance in rice.…”

Behaviours of some Rice Cultivars Treated with Cycocel under Wa-ter Stress Condition

“…The main trait that is selected for drought tolerance is the grain yield under stress. Drought effect seed yield depends on the duration of watering from flowering until physiological maturity (Sakran et al, 2020).…”