四、多倍体在物种进化和育种上的意义多倍体是自然界普遍存在的客观事实。大约一半的被子植物,三分之二以上的禾本科植物是多倍体,其中就有不少经济价值很高的作物,如小麦、燕麦、棉花、烟草、油菜、甘蔗、马铃薯、甘薯、花生、葡萄、香蕉、苹果、梨、草莓等大多是多倍体。这个事实说明,多倍体的形成规律,不论在植物的进化上或作物育种上都是很重要的。以小麦属的多倍体系为例:一粒小麦为二倍体(2X,染色体14个), Fourth, the significance of polyploid evolution and breeding in the species Polyploidy is an objective fact that exists in nature. About half of the angiosperms and more than two thirds of the grasses are polyploids, among which are many crops with high economic value such as wheat, oats, cotton, tobacco, canola, sugar cane, potatoes, sweet potatoes, peanuts Grapes, bananas, apples, pears, strawberries, etc. are mostly polyploid. This fact shows that the formation of polyploidy, both in plant evolution and crop breeding are very important. Take wheat genus system as an example: a wheat is diploid (2X, 14 chromosomes)