第二期稻作低產原因之研究(3)不同溫度持續對水稻之分蘖及光合作用能力之影響

Abstract

本試驗研究乃利用第1期稻作期間之自然太陽光照，於人工控制氣候室進行二種溫度持續處理；一為仿第1期稻作之氣溫條件，二則仿第2期稻作之氣溫條件，以探討第2期稻作低產之原因及其限制因素。結果摘要如下： (一)水稻生育期間仿第2期稻作之氣溫(由高溫降至低溫)處理，則其有效分?數乃較仿第1期稻作之氣溫(由低溫升至高溫)處理者為少。 (二)水稻生育期間仿第2期稻作之氣溫處理時，其抽穗期之葉面積及葉綠素含量均較仿第1期稻作之氣溫處理者為低，且其單葉之光合作用能力亦然。 (三)利用1期稻作期間之太陽輻射(出穗期之平均日輻射量300 cal.以上)，但仿2期稻作期間之氣溫處理時，抽穗期之氣溫低(晝間20℃，夜間15℃)，結實不良。 綜合本試驗研究結果知，第二期稻作之氣溫過高(30℃以上)乃是分數減少之限制因素。而結實率低之問題，北部地區之光合成量低及低溫，同為其主要限制因素，其影響之輕重問題，有待研究。 The purpose of this study was to elucidate the causes of low yielding and the limiting factors in the second crop of rice. Experiment was carried out under the natural solar radiation of the 1st crop season, and rice plant was cultured within the phytotron at two temperature duration treatments; the one was modified the temperature of the 1st crop season (from low to high temperature) and the other one was modified the 2nd crop season (from high to low temperature). Results were summarized as follows: 1. The effective number of tilleres was lesser in the temperature duration treatment of modifying the 2nd crop season than the 1st crop. 2. The percentage of ripened grains was lower in the temperature duration treatment of modifying the 2nd crop than the 1st crop. 3. The leaf area and chlorophyll content at heading stage was lower in the temperature duration treatment of modifying the 2nd crop season than the 1st crop, and the photosynthetic activities was the same too. In conclusion, the high temperature (above 30℃) is the limiting factors for tillering, and the lower temperature and low solar radiation is the limiting factors for grains ripenning in the 2nd crop of rice in northern part of Taiwan.