Development of Two Novel Photoperiod and Thermo-Sensitive Genic Male Sterile Lines in Rice (Oryza sativa L.)

Abstract

Developing hybrid rice by two lines system under Egyptian conditions requires high performance lines. The promising Photoperiod and Thermo-sensitive Genic Male Sterile (PTGMS) lines A001S and G001S were developed by crossing, continuously inbred for six generations,and the selection depended onduration and tillering ability. F2 populations were segregated and fitted well to the ratio of 15:1 for pollen grains fertility trait, indicating the presence of digenic inheritance and epistatic dominant duplicate gene action control. The PTGMS line G001S had the most desirable characteristics for the hybrid rice breeders, with values of 19cm panicle length,13 primary branches panicle -1 , 8.5mm grain length, 2.9mm grain width, 1.9mm grain thicknessand 25g for 1000-grain weight. Both A001S and G001S were superiors of most studied traits to be good PTGMS lines for two-line hybrid seed production systems. Both linesexhibited a high rate of panicle exertion with values of 90.70 % and 94.30 % for A001S and G001S, respectively. The two lines were completely male sterile when sowing from 1 st to 20 th April. Still, their fertility alternated from completely sterile to partially fertile in late July when the temperature decreased and the day length was long. A001S x GSR1 and G001S x GSR9 new hybrid combinations were derived from the newlydeveloped PTGMS lines; A001S and G001S, with short duration, semi-dwarf and high tillering ability with a high yield potential of 80gplant -1 . For the panicle and grain traits, both hybrids exhibited good characteristics.Both hybrids showed favorable positive significant, and highly significant standard heterosis.