在实现玉米机械化收获前,美国玉米带多年来选用单穗型玉米。其原因是: 1.农民觉得收获单个大穗比在一株上收获较多的小穗方便; 2.多年来习惯于选大穗留种,而大穗经常来自单穗型植株,使种单穗型的倾向得以保持; 3.在以往,种子展览非常盛行,在展览中大穗往往赢得大的荣誉。 In the United States before the corn mechanization harvest, the United States corn with single-spike corn. The reasons for this are: 1. Farmers find it easier to harvest a single large spike than to harvest more spikelets on one plant. 2. They have been accustomed to selecting large spikes for many years, while large spikes often come from single-spike plants, The tendency of panicle type to be maintained; 3. In the past, seed exhibitions were very prevalent, and big spikes in exhibitions often won big honors.