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选育推广早熟高产玉米杂交种已成为国内外的研究趋势。法国从五十年代就开始集中精力选育前期耐低温、后期籽粒能正常成熟的玉米杂交种和品种。使玉米种植范围向北扩展了200℃的积温带,全国平均亩产由原来的226斤提高到617斤。苏联从1951年开始育成一批早熟自交系,1958年末白俄罗斯共和国推广了早熟高产自粒玉米双交种“Bup25”,比当地良种增产10.7—21.6％,早熟七天以上。加拿大25年来由于推广早熟高产玉米杂交种,使玉米种植区向北推进了150公里。美国在七十年代用早晚熟种杂交,再用早熟种回交的办法育成了仅68天成熟,
Breeding and promoting early-maturity and high-yielding corn hybrids have become the research trends both at home and abroad. France from the fifties began to focus on breeding early low temperature, the late maturity of the grain corn hybrids and varieties. The maize planting area expanded northwards by a temperature of 200 ° C. The national average mu yield increased from 226 to 617 kg. Since 1951, the Soviet Union has bred a group of early-maturing inbreds. In late 1958, the Republic of Belarus promoted “Bup25”, a early-maturing and high-yielding self-bred maize double breed, yielding 10.7-21.6% more than the local elite and more than seven days premature. In the 25 years since Canada popularized precocious and high-yielding maize hybrids, the corn planting area has been pushed north by 150 kilometers. The United States in the seventies with early and late hybrids, and then backcrossed early maturing bred only 68 days mature,