The impacts of nighttime post-anthesis warming on rice productivity and grain quality in East China were evaluated for two cultivars, II You 128, an indica rice, and Wuyunjing 7, a japonica rice. Warming by 3.0 °C stimulated the nighttime respiration rate and decreased the photosynthesis rate, resulting in significant decreases of 21.2% and 24.9% in aboveground biomass accumulation for II You 128 and Wuyunjing 7, respectively. Warming significantly reduced the rates of seed setting and grain filling, especially of inferior kernels(those lower in panicles), while the filling rate of superior kernels remained almost unchanged. As a result, 1000-grain weight and grain yield were respectively 3.7% and 30.0% lower for II You 128 and 12.8% and 34.3% for Wuyunjing 7 in warmed plots than in the unwarmed control. Nighttime warming also significantly reduced the grain milling and appearance quality of both varieties. More negative effects of warming on inferior than on superior kernels were found. The above results have important implications for rice variety cultivation in East China.
【目的】明确气候变暖对作物生产的实际影响,降低对未来粮食安全预测的不确定性。【方法】依据东北水稻生产和气候变化的长期观测数据,并结合田间开放式增温试验(free air temperature increase,FATI),系统研究稻作系统对气候变暖的实际响应与适应。【结果】历史数据分析发现,近几十年来东北水稻单产与其生长季的气温呈明显递增趋势,相关显著,但与降水量变化相关不显著。理论推算表明,水稻生长季最低气温升高1℃,水稻单产可提高6.0%以上。田间试验发现,在目前的气温背景下,水稻冠层气温升高1℃,单产可提高10%左右。近四十年来东北水稻新品种的生育期每10年约延长3 d,与近二十年来田间观测到的水稻实际生育期延长幅度基本一致,达5 d左右;与1970年相比,2010年黑龙江省的水稻种植面积扩大了24倍,种植重心向北位移了近110 km,与东北水稻生长季≥10℃有效积温带北移的幅度一致。【结论】气候变暖对东北水稻的直接增产效应显著,稻作系统可以通过品种改良、栽培改进和区域调整等策略来逐步适应气候变化的趋势。在应对气候变化的稻作制度调整上,应充分挖掘增温的增产效应及作物系统的适应潜力,调整时机和幅度应适当迟后于预测的气候变化进程。在气候变暖的大趋势下,要注意因水稻生育期延长和种植区域北扩而可能遭遇的低温冷害等极端性天气。
