The Study Of Inner And Outer Cause Of Low Setting Percentage Of Leymus Chinensis

Leymus chinensis is a perennial grass. L. chinensis has three low questions of tassel percentage and setting percentage and bourgeon of seed percentage, especially low setting percentage in nation. It limits the seed production and artificial pasture construction. This paper researches on the L. chinensis on the Songnen Plains of China,the cause of low percentage is divided into : flower structure in different position of spikelet; pollen and stigma energy in different position of spikelet; different tassel diversity; different tassel period; adding N-fertilizer; different style of leaf color; it is six aspects in total, in order to find the inner and outer cause of low setting percentage and offer a theoretical guidance to explain the process of L .chinensis sexual reproduction and to enhance the seed production.1 The relationship of flower structure in different position of spikelet and flower with seed production and setting percentageThe study of flower structure can find that the length and width of stamen and pistil in different position of spikelet and flower is not the sanme,and seed production and setting percentage are different in different spikelet position and flower position; seed production and setting percentage of middle and under spikelet and flower near to the base of spikelet are higher, it is 0.53g per 20 spikelet and 19.45%. It illustrated the development of different spikelet and flower is different. The result showed that seed production and setting percentage has no relationship with flower structure。2 In total spikelet, the highest pollen energy and stigma energy is located in the middleFlower of middle spikelet and the lowest pollen energy and stigma energy is located in the upper flower of upper spikelet, with 86% and 87.5% highest and 46% and 52% lowest. Pollen energy presented: middle spikelet>under spikelet>upper spikelet. In different position of spikelet, the pollen energy and stigma energy are not the same. It illustrated the development of flower is not the same to influence the pollen energy and stigma energy.3 According to 180 m-2 to 450 m-2, the highest seed production and setting percentage is 0.093g per spikelet and 54.5% highest setting percentage on the condition with 450m-2, and lowest seed production and setting percentage is 0.041g and 25.5%. With tassel density increasing, the seed production and setting percentage present increasing trend, it is relation with different tassel diversity and different quantity of pollen.4 The influence of different tassel period on seed productionThe investigation on seed production and setting percentage per spikelet can show that the seed production and setting percentage in middle tassel period is 0.087g and 40.45%, with 0.073g and 29.39% in before period and 0.073g and 32.71% in last period.5 The seed production and setting percentage of different leaf color style and the investigation of seed trend.Different leaf color style of L. chinensis showed that green-yellow seed production and setting percentage is 0.093g and 53%; and the middle style is 0.080g and 47% and green-grey style with 0.07g and 35%; green-yellow seed production and setting percentage is higher than the middle style and green-grey style.It is relation with style of L. chinensis. The rule of setting percentage in different spikelet of different leaf color style of L. chinensis still showed that the middle and under spikelet is the highest and upper spikelet is the lowest.6 The seed production and setting percentage with N-fertilizer is higher than that with no-fertilizer. It showed that the N-fertilizer after booting period can enhance seed production.