中文摘要：

在水稻（Oryza sativa L.）灌浆结实期进行高温与干旱双重胁迫处理,研究其对水稻产量与品质的影响。结果表明,高温与干旱双重胁迫显著降低了水稻的每穗总粒数、结实率和千粒重,各因素相对于对照的下降幅度均随胁迫时间的延长而增大,高温胁迫导致的结实率大幅度下降是造成产量下降的主要原因。在不同胁迫处理间,减产率从小到大的排序为：适温—中度干旱（OT-MD）〈高温—正常供水（HT-WW）〈适温—重度干旱（OT-SD）〈高温—中度干旱（HT-MD）〈高温—重度干旱（HT-SD）。各胁迫处理的减产率均表现出随胁迫时间延长而增大的趋势,各处理的减产率在胁迫30 d前增加的幅度较大;在30-40 d,除高温—重度干旱（HT-SD）胁迫处理外,其他处理减产率的增加幅度较小。高温胁迫、干旱胁迫以及高温干旱的双重胁迫均引起水稻糙米率、精米率的下降,导致稻米碾磨品质变差。糙米率、精米率下降以高温胁迫处理的最大,与适温处理相比,分别降低14.77%和14.09%。

英文摘要：

High temperatures and droughts frequently occur in rice（Oryza sativa L.） production regions in South China due to local topographic conditions. It has resulted in simultaneous decline in rice yield and quality.This study investigated the combined effects of high temperature and drought stress on rice yield and quality at grain-filling stage. Six cases were considered, including 3 cases of optimal temperature with well-watered condition（OT-WW）, moderate drought（OT-MD）, and severe drought（OT-SD）, and 3 cases of high temperature with well-watered condition（HT-WW）, moderate drought（HT-MD）, and severe drought（HT-SD）. The OT-WW was taken as the control treatment（CK）. In addition to CK, treatment durations were set at 10, 20, 30 and 40 days, respectively. The results showed that the combined stress of high temperature and drought had significantly reduced grain number per spikelet, seed setting rate and thousand-grain weight in rice. With the treatment time prolonged,the decline was increased in comparison with that of the CK case. The main reason of yield decline was the seed setting rate reduced heavily under high temperature treatment. According to injury index of grain number perspikelet, seed setting rate and thousand-grain weight under high temperature and drought stress, the yield decrement rate of rice was calculated and compared with the control case. The results showed that the order of decrement rate between different treatments were as follows： optimal temperature- moderate drought（OT-MD） 〈high temperature-well-watered（HT-WW）〈 optimum temperature- severe drought（OT-SD）〈 high temperature-moderate drought（HT-MD）〈 high temperature- severe drought（HT-SD）. The decrement rate increased with the prolonged time of treatment, and the yield decreased more obviously in 1-30 d after treatment. In 30-40 d, the yield of rice reduced slowly under the treatments except for HT-SD. The stress of high temperature and drought alone or both combined can also reduce br