Shading Effects On Photosynthetic Characteristic And Yield Of Potato In Different Growth Stages

In order to study the effects of different shading treatments on the photosynthetic characteristics and yield of potato in different growth periods,and to make clear the tolerance of potato in different growth periods to low light stress,two shading treatments(20% shading rate and 50% shading rate)were carried out on two potato varieties in four growth stages(seedling,seedling-squaring stage,squaring stage-flowering,flowering-harvest)The relationship between low light stress and chlorophyll content,photosynthetic carbon assimilation capacity,dry matter and starch content,yield,commercial potato rate and economic characteristics of a single plant were stuied.The results show that:(1)Shading effects on potato were different in different growth period.The results showed that: In the seedling stage the relative content of chlorophyll and the net photosynthetic rate decreased significantly,but the dry matter and starch content did not change significantly.In the seedling-squaring stage,the relative content of chlorophyll in potato leaves increased,but the yield,dry matter and starch content did not change significantly.In the squaring stage-flowering stage,The relative content of chlorophyll and the number of tubers per plant increased,but the yield,commercial tuber rate,dry matter and starch content did not change significantly.The relative content of chlorophyll increased and the variation of photosynthetic index was small after 15 days of flowering harvest shading,while the yield,dry matter and starch content decreased significantly after 60 days of shading from flowering to harvest stage.(2)The relative content of chlorophyll increased after 10 days,15 days and 25 days of continuous shading from flowering to harvest,and the photosynthetic indexes such as net photosynthetic rate showed a more complex trend,and gradually reached the normal level with the extension of shading days.(3)The effect of 50% shading stress on potato was greater than that of 20% shading treatment.The chlorophyll of 50% shading treatment increased significantly,and the net photosynthetic rate and yield decreased significantly.(4)The low light stress tolerance of Jizhangshu No.12 was better than that of Jizhangshu No.8.The decrease of net photosynthetic rate of Jizhangshu No.12 was lower,and the decrease of dry matter and starch content was not significant.