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一、课题提出的依据和目的意义 回顾近八十多年的水稻育种史可以知道,水稻育种经历了三个阶段。本世纪六十年代以前,是农家品种的整理和利用阶段,产量虽有所提高,但幅度不大,因为这类品种均属高秆类型,收获指数低(30%左右),且易倒伏,亩产在400-500斤的水平上徘徊了几十年;六十
First, the basis for the issue and purpose of the significance of Recalling nearly eight decades of rice breeding history can know that rice breeding has gone through three stages. Before the sixties of this century, it was a period of finishing and utilizing farm varieties. Although the yield was increased, the increase was not significant because these varieties were of the tall stalk type with a low harvest index (about 30%) and were easily lopsided. Yields have hovered at the level of 400-500 pounds for several decades; sixty