我们从1966年起,就承担了繁殖“农大7号”(母本3811×金15,父本w20×w24)双交种玉米的制种任务.但由于栽培技术不当,管理上不够细致,几年来亩产很少超过千斤.1971年初,我们发动群众总结了经验和教训,并在整地、施肥、播种方法、密度、田间管理等方面作了改进,1971年和1972年,“农大7号”双交种制种田连续两年大面积亩产超过了千斤.1971年135.36亩双交种玉米,亩产1,089斤,其中5.2亩丰产田,平均亩产1,236斤;1972年双交种玉米面积80.5 Since 1966, we have undertaken the task of seed breeding of double crosses of maize breeding “Nongda 7” (female 3811 × golden 15, male parent w20 × w24), but due to inadequate cultivation techniques, the management is not detailed enough In the early 1971, we mobilized the masses to sum up experiences and lessons learned and made improvements in soil preparation, fertilization, sowing methods, density, and field management. In 1971 and 1972, “Nongda No. 7 ”double cross breeding system for two consecutive years of large-area mu produce more than a kilogram .1971 135.36 acres of double cross-planting corn, per mu 1,089 pounds, of which 5.2 acres of high-yielding fields, an average of 1,236 pounds per mu; 1972 double Corn area of ​​80.5