Abstract

Shuangdi Pei eS, a thermo-sensitive genic male sterile (TGMS) rice line with eui gene is derived from TGMS rice line Shuangdi S by irradiation with 350 Gy⁶⁰Co γ-ray. To elucidate the uppermost internode elongation of TGMS line with eui gene, Shuangdi Pei eS and its original TGMS line Shuangdi S were used to study the effects of temperature on panicle exsertion. At 25°C, the uppermost internode of Shuangdi Pei eS had the quickest elongation from the 4^th day before flowering to 0 day (flowering), being 2.1-fold as that of Shuangdi S, whereas it elongated slowly during the 12^th day to the 4^th day before flowering and the 1^st to the 3^rd day after flowering. The uppermost internode of Shuangdi Pei eS exserted from the flag leaf sheath at 23, 25 and 27°C, respectively, and the length of elongated uppermost internode increased with the decreasing temperatures. At 30°C, though the panicles of Shuangdi Pei eS were still enclosed in the leaf sheath, the degree of panicle enclosure was significantly lower compared with Shuangdi S. Cytological studies on Shuangdi Pei eS which showed that the uppermost internode elongation was attributed to the increase of cell number and cell elongation, and the latter was more significant. Moreover, the numbers of outermost and innermost parenchyma cells and the cell length of the uppermost internode reduced with the increasing temperatures.

Key words: Rice (Oryza sativa L.), thermo-sensitive genic male sterility (TGMS), elongated uppermost internode gene (eui), panicle exsertion, temperature.