江苏近50年粳稻安全齐穗期的变化

确定水稻安全齐穗期是安排各品种播栽期的重要依据。本研究应用江苏由北至南4个代表性地点(赣榆、淮安、扬州和吴县)近50年(1958—2007) 5~11月逐日日平均温度资料，根据生产上常用的耐寒性较弱和较强的粳稻安全齐穗期的温度指标，得出了近50年及其前25年和后25年4地点两类粳稻保证率为50%、80%和90%的安全齐穗日期，发现后25年各地的安全齐穗日期较前25年普遍延迟，延迟的幅度在3~4 d；后25年各地的安全齐穗日期的变异亦明显增大。进而提出了北南各地点一般粳稻安全齐穗日期分别为9月18日、9月20日、9月24日和9月28日，这比目前各地生产中习惯应用的安全齐穗日期迟约4~6 d。本文分析方法可以供我国各稻区相关研究参考，其结果也可供我国类似稻区借鉴，并在气候变暖的大背景下对水稻安全齐穗期的变化给予新的认识。指出应对现用主体粳稻品种出穗开花期的耐寒性进行观察研究，确定出各地各类型粳稻品种的安全齐穗日期，以更具体准确地指导水稻播(栽)期的安排。

Changes of Safe Dates for Full Heading in Japonica Rice over Past 50 Years in Jiangsu Province

Determining the safe dates of full heading of rice is very important for arranging sowing and transplanting dates. In this study, the daily average temperatures from May to November during the 50 years (1958–2007) in four regions from north to south in Jiangsu Province (Ganyu, Huai’an, Yangzhou, and Wuxian city) were analyzed. According to the normal indices of temperatures for the safe dates of full heading in japonica rice cultivars with weaker and stronger cold tolerance, safe dates of full heading were obtained for the 50 years from 1958 to 2007, the first 25 years, and the second 25 years. The guarantee rate for the safe dates was 50%, 80%, and 90% respectively. It was observed that the safe dates of full heading during the second 25 years were three to four days later than those during the first 25 years. Variation in the safe dates of full heading was greater for the second 25 years than for the first 25 years. The safe dates of full heading at the four regions from north to south were 18th September, 20th September, 24th September and 28th September, respectively, and were four to six days later than those currently used in these regions. As the global whether is warming, these results could be utilized as references for the production in different rice-growing areas. More experiments should be conducted to observe cold tolerance of rice cultivars during heading and flowering, and to obtain the safe dates of full heading for major varieties, so that more exact sowing and transplanting dates could be got in japonica rice.