本世纪二十年代初,美国育成了第一个双交玉米种,从此使玉米的产量迅速提高,它的问世成为现代农作物育种的一次突破。六十年代,科学家用传统的杂交法先后育成矮秆、高产的“墨西哥小麦”和“菲律宾水稻”品种。该品种不仅在当地种植成功,而且在许多亚非拉国家中推广也大见成效。许多国 The early twenties of this century, the United States bred the first double-cross corn, then the yield of corn increased rapidly, its advent of modern crop breeding a breakthrough. In the 1960s, scientists dwarfed and dwarfed “Mexican wheat” and “Philippine rice” varieties using traditional hybridization methods. The breed has not only succeeded in planting it locally, but it has also achieved fruitful results in many Asian, African and Latin American countries. Many countries