应用数学模型研究上海县油菜生产力的变化

为了定量分析诸科技因子与自然因子对上海县1955—1988年油菜生产力发展变化的贡献和作用,建立了油菜生产力的专家模型、道格拉斯模型和趋势产量模型。研究结果表明,趋势产量于1978年达峰值。1978年比1955年每亩趋势产量提高72.9公斤,增产132％。其中,品种更换、栽培技术改进、施肥水平与地力变化和三因子综合作用对产量增长的贡献分别占54％、36％、15％和27％。1988年比1978趋势产量下降24.3公斤,减产19％。四者对产量变化的作用分别为1.6％、-6.4％、-7.2％和-7.0％。筛选出对当地脉动产量构成较大影响的7项气候指标,其综合丰歉指数的变幅达40％—-60％,丰年平均增产率为27.2％,歉年平均减产率为22.6％。对脉动产量产生较大影响的病虫危害年,大体上三年一遇,平均减产指数为5.7％,个别严重危害年的减产指数可达30％。

STUDY ON CHANGE OF RAPE PRODUCTIVITY IN SHANGHAI COUNTY BY MEANS OF MATHEMATICAL MODEL

Empert model,C-D model,and trend yield model were set in order to quantitatively analysing the contribution and role of scientific and technological factors and natural factors to the land productivity of rape during the 1955-1988 in Shanghai County.The result showed that t,he trend yield of 1978 reached the peak of curve.The trend yield of 1978 was 72.9 kg/mu more than that of 1955.The increasing rate was about 132%.In the total rate,the contribution of variety change,cultural improvement,the application of fertilizer,and soil productivity was 54%,36%,15%,and 27% respectively.However,the trend yield of 1988 was 24.3kg/mu less than that of 1978 and the decreasing rate was 19%.The contribution of four factors was 1.6%,-6.4%,-7.2% and-7.0% respectively.Among the local climate factors,the most important affection to the rape yield was made by 7 factors,the extent of comprehensive index of meteorological factors was 40-60%.The average increasing rate of bumper harvest year was 27.2%.The average decreasing rate of disaster years was 22.6%.The serious disaster affecting the rape yield owing to pests and diseases happened about once 3 years and made loss about 5.7% each year during the past 34 years.In some most strious years,the loss index could be up to 30%.