双季籼稻安全生长期研究方法择优与应用——以长沙为例

Selection and Application of Research Methods for Safe Growth Period of Double Cropping Indica Rice:Take Changsha as an Example

利用长沙1961—2020年逐日日平均气温和1996—2020年双季稻发育期等观测资料,通过不同统计方法、不同界限温度等适用性对比分析,优选了双季籼稻安全生长期研究方法,并应用于长沙双季稻安全生长期研究。结果表明:界限温度日期统计采用连续统计法,以气温8℃为早稻播种界限温度,以22℃为晚稻齐穗界限温度,以气温连续3 d≥8℃初日至连续3 d≥22℃终日日数为双季稻安全生长期,该结果适用于长沙双季稻安全生长期研究,或可适用于覆膜育秧的其他双季籼稻区;长沙地区,≥8℃的80%保证率日期是3月21日,界限温度≥8℃播种期显著提前;晚稻安全齐穗80%保证率日期是9月9日,安全齐穗期推迟但不明显;双季稻安全生长80%保证率日数超过179 d,安全生长期极显著增加。

Based on the observation data of the daily average temperature in Changsha from 1961 to 2020 and the development period of double cropping rice from 1996 to 2020,through the comparative analysis of the applicability of different statistical methods and different boundary temperatures,this paper optimizes the research method of safe growth period of double cropping indica rice and applies it to the long-term study of safe growth period of double cropping rice in Changsha.The results show that the continuous statistical method is adopted for the boundary temperature statistics.The air temperature of 8℃is used as the sowing boundary temperature of early rice,and 22℃as the full panicle boundary temperature of late rice.The number of days from the first day of 3 consecutive days when the air temperature≥8℃to the last day of 3 consecutive days when the air temperature≥22℃is used as the safe growth period of double cropping rice.These indices are suitable for the study on the safe growth period of double cropping rice in Changsha or other double cropping indica rice areas covered with plastic film.In Changsha Area,80%of the guarantee rate≥8℃is on 21 March,and the sowing date with boundary temperature≥8℃is significantly ahead of schedule;the date of 80%guarantee rate of safe full heading of late rice is 9 September,and the safe full heading date is delayed but not obvious.The safe growth rate of double cropping rice is 80%,the number of days exceeded 179 d,and the safe growth period is prolonged significantly.