Effect of The Degree and Duration of Low Temperature on the Degeneration and Sterility of Spikelets in Rice

저온(低溫)의 정도(程度)와 기간(期間)이 수도(水稻)의 영화퇴화(穎花退化)와 불임(不稔)에 미치는 영향(影響)

In order to evaluate cold tolerance and to counter measure the cold damage of newly released rice varieties, the effects of degree and duration of low temperature at the meiotic stage on the sterility and ripening of rice spikelets were investigated and the results were as follows: 1. As the temperature was lowered and the duration of low temperature was extended during the meiotic stage, the heading dates were delayed and the sterility were increased. The main factor for the low yield due to low temperature was due to the increased sterility, and under the below $15^{\circ}C$, the delayed heading was also responsible for the low yield. 2. The sterility and delayed kernel development of rice were increased when grown at $15^{\circ}C$ for six days. 3. The newly released rice varieties were highly sensitive te low temperature damage during the meiotic stage. The treatment of rice at $15^{\circ}C$ for four days might be used as a perameter to evaluate the low temperature tolerance of rice varieties.

수도(水稻) 신품종(新品種)들의 내냉성(耐冷性) 판별(判別)과 냉해대책(冷害對策)을 위하여 생식생장기(生殖生長期)에 있어서 저온(低溫)의 정도(程度)와 기간(期間)이 임실(稔實)과 등숙(登熟)에 미치는 영향(影響)을 검토(檢討)하여 다음과 같은 결과(結果)를 얻었다. 1. 수도(水稻) 감수분열기(減數分裂期)에 있어서 저온(低溫)의 정도(程度)가 크고 기간(期間)이 길어 질수록 출수(出穗)가 지연(遲延)되고 불임(不稔)이 증가(增加)하였으며 저온(低溫)에 의(依)한 감수(減收)는 주(主)로 불임증가(不稔增加)에 기인(基因)하였으나 $15^{\circ}C$의 저온(低溫)에서는 출수(出穗) 지연(遲延)도 관여(關與)하는 것으로 보였다. 2. $15^{\circ}C$ 6일간(日間) 처리(處理)에서는 불임(不稔)과 발육정지립(發育停止粒)이 다 같이 증가(增加)하고 완전(完全) 발숙립(發熟粒)은 거의 없었다. 3. 신품종(新品種)들은 기존(旣存) 품종(品種)보다 생식생장기(生殖生長期) 냉해(冷害)가 현저(顯著)하였고 내냉성(耐冷性) 검정(檢定)의 parameter로서는 감수분열기(減數分裂期)의 $15^{\circ}C$ 4일간(日間) 처리(處理)가 적당(適當)한 것으로 보였다.