HETEROSIS AND COMBINIG ABILITY OF SOME RICE GENOTYPES UNDER NORMAL AND WATER DEFICIT CONDITIONS

doi:10.12816/ejpb.2019.256686

HETEROSIS AND COMBINIG ABILITY OF SOME RICE GENOTYPES UNDER NORMAL AND WATER DEFICIT CONDITIONS

Document Type : Original research

10.12816/ejpb.2019.256686

Abstract

Rice is a major staple food crop worldwide, but its production is greatly affected by water deficit. Therefore developing rice drought tolerant genotypes is essential, especially, under current water shortage conditions. The present investigation was carried out at the Experimental Farm of Rice Research Department, Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2017 and 2018 summer seasons using seven diverse rice genotypes. All possible cross combinations excluding reciprocals were made among the seven genotypes, giving 21 F₁ crosses. The seven parental genotypes and their 21 F₁ crosses were evaluated in two separate experiments under normal and water deficit conditions. Randomized complete block design (RCBD) with three replications was used for each experiment. The objective was to estimate combining ability, heterosis and nature of gene action for nine traits under normal and water deficit conditions. The results indicated that water deficit significantly decreased the means of all studied traits for parents and their hybrids. Highly significant differences were found among genotypes, parents and crosses for all the studied traits under normal and stress conditions. Mean squares due to parents vs. crosses (average heterosis) were significant for all the studied traits. General (GCA) and specific (SCA) combining ability mean squares were highly significant for all the studied traits under both normal and stress conditions. The non-additive gene action played an important role in the inheritance of the majority of the studied traits. The parents Sakha 102 and Sakha 106showed the best desirable GCA effects for earliness, whereas the parents Giza 178, Sakha 104 and IET 1444 appeared to be the best general combiners for grain yield/plant and some of its components. The seven crosses (Giza 178 × Sakha 102), (Sakha 104 × IET 1444), (IRAT 170 × IET 1444), (IRAT 170 × Moroberekan), (Moroberekan × Sakha106) and (Moroberekan × Sakha102) had the best SCA effects for grain yield/plant as well as one or more of its components under both conditions. Moreover, the three crosses (Sakha 104 × IET 1444), (IRAT 170 × IET 1444) and (Moroberekan × Sakha102) showed significant and desirable better parent heterosis (heterobeltiosis) for grain yield/plant under both conditions. Hence, these hybrids would be valuable in rice breeding for improving yielding ability under normal and water deficit conditions.

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