1951～1996年上海粮食产量变化特征分析

ANALYSIS OF GRAIN YIELD VARIATION FEATURES IN SHANGHAI IN 1951～1996

根据上海市1951～1996年的粮食产量资料分析，结果表明目前粮食单位面积产量变化处在稳步增长期，预计到2004年粮食单位面积产量可达9000kg／hm2，稻谷单位面积产量2003年达10050kg／hm2；在粮食总产量中稻谷占3／4；1987年以来，粮食种植面积波动对总产量波动的影响占60％，已超过单位面积产量波动的影响；粮食单位面积产量年际波动的90％是因气象条件的变化所致；粮食年产量变化存在明显的周期波动，粮食总产量有16．4a、11．2a的周期，粮食单位面积产量有4．8a和2．9a的周期；1987年大面积种植单季晚稻以来，影响粮食单位面积产量变化的气象条件与1987年之前有着明显的差异。

Based on the grain yield data in Shanghai in 1951 ~ 1996, the variation fea-tures of grain yield and their relationships with the associated meteorological factors were an-alyzed. The annual grain yield per unit area is going up steadily in recent years. The grain yield per unit area will be 9OOO kg/hm' in 2OO4,the rice yield will be 1OO5O kg/hm' 1n 2OO3.The rice yield accounts for 75 % of the total grain yield. The influence of fluctuations of grain yield per unit area on the total grain yield is less than that of fluctuation of total planting area of grains from 1987 on. The 9O% of fluctuations of grain yield per unit area are caused by the variation of meteorological factors. There are notable cyclical fluctuations in variation of the annual grain yields,the fluctuation cycles are 16. 4 years and 11. 2 years for the total grain yield, 4. 8 years and 2. 9 years for the grain yield per unit area. Since 1987,late rice is planted in extensive area. The meteorological factors influencing the variation of grain yield per unit area from 1987 on differ obviously with those before 1987.