Combining ability for some root, physiological and grain quality traits in rice (Oryza sativa L.) Under water deficit conditions [electronic resource].

Includes references.

rice at the Experimental Farm of Rice Research and Training Center, Sakha, Kafr El-Sheikh, Egypt during 2009 and 2010 rice growing seasons, to investigate the nature of gene action governing the various traits studied and 10 explore the combining ability behavior of various genotypes used in the studies. Eight root. agro-physiological and grain quality traits were included in the study in F1 generation. It was conspicuous from the results that GCA variance was greater than the SCA variance for all the studied traits, indicating the preponderance of additive gene action for these traits. The GCA/SCA ratio was greater than unity for root length (1.07) and grain length (1.13) exhibited that additive gene action was played a remarkable role in the inheritance of these two traits and could easily manipulated for genetic improvement. On the contrary, the non-additive effects were more pronounced for root volume, root/shoot ratio, milling %, amylose content. and chlorophyll content indicating that their genetic improvement under water deficit conditions was a tedious exercise. The estimates of GCA effects indicated that parents, Balado and Wab 878 were good combiners for grain length and amylose content. The parent Wab• 450 was a good general combiner for root length, root volume, chlorophyll content and grain length. In addition, Gaori and GZ 1368 were the best general combiners for root/shoot ratio and milling %. Sakha 104 was a good combiner for only milling %. Moreover, the cross combinations, Sakha 102 X GZ 1368, Wab 450 X Gaori and IET1444 X Gaori appeared to be the best ones for root length and root volume since they exhibited a significantly positive SCA effect and some of them involved parents with high GCA. Moreover, the cross combinations, Sakha 102 X Gaori, Sakha 104 X lET 1444, lET 1444 X Wab 878 and IET 1444 X GZ 1368 exhibited high sea and included at least one parent having good gca for milling %. Results further indicated that 19. 7, 8 and 8 crosses had significant positive better parent heterosis for root volume, root/shoot ratio, chlorophyll content. and grain length. Moreover, highly significant estimates of heterosis were recorded in Sakha 102 X Sakha 104, Sakha 102 X lET 1444, Sakha 102 X GZ 1368, Balado X Wab 450, Balado X lET 1444, Balado X Wab 878 and lET 1444 X Wab 878 'rice genotypes for grain length. On the either hand, IET 1444 X Gaori rice hybrid exhibited either highly significant positive estimates of heterosis for root volume, root/shoot ratio or negative for amylose content %. Among the studied crosses, Balado X IET 1444 and lET 1444 X GZ 1368 obtained highly significant heterosis when they measured as a deviation from better parent for root length and milling %, respectively. The phenotypic correlation coefficient was found to be highly significant positive between root length and each of root volume, root/shoot ratio and chlorophyll content %. Root volume was phenotypically associated with root/shoot ratio and chlorophyll content %. Moreover, chlorophyll content was correlated with root/shoot ratio. Regarding grain quality traits, grain length was significantly and positively correlated with milling % and amylose content% Key words: rice - root traits - chlorophyll content - grain quality ~ combining ability, heterosis

Summary in Arabic.

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