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玉米是高产稳产作物,适应性广,增产潜力大,特别是杂交种玉米,增产更为显著。目前生产玉米的先进国家,都以推广自交系间杂交种作为提高单产的主要手段之一。近十年来,我国以推广单交种为主的三交、双交和综合品种,已占杂交种面积的55％,而河南省更广,1979年占到77％。由于种植杂交种面积逐年扩大,相应地加大了制种任务。一般增产种子有两条途径:一是扩大制种面积,一是提高制种单产。扩大制种面积,在单交比双交制种减产较多情况下,也就相应抵消杂种优势的增产作用。所以主要应放在提高制种单产方面,才
Corn is a high-yield stable crop, wide adaptability, large potential yield, especially hybrid corn, yield more significant. At present, the advanced countries that produce corn have all promoted the promotion of hybrids among inbred lines as one of the major means to increase yields. In the past ten years, the three cross-breeding, double cross breeding and comprehensive varieties that mainly promote the single cross-breeding in our country have accounted for 55% of the hybrid cross-breeding area, while Henan Province has a wider coverage and accounted for 77% in 1979. Due to the year-by-year expansion of planting hybrids, the seed production task has been correspondingly enlarged. There are two ways to increase the yield of seeds: First, to increase seed production area; first, to increase seed production. Expand the seed production area, in the single cross than the double cross cut production more cases, it will offset the heterosis increased yield. Therefore, we should mainly focus on improving the seed production, only