| Nitrogen and potassium on the yield formation of root tuber of sweet potato has an impact,but for soil N/K ratio on the yield of sweet potato research rarely reported,so in order to investigate effects of soil N/K ratio on root tuber yield formation of sweet potato,We using starch-Ji Xu 23 and starch-Shang Shu 19 varieties of sweet potato,A randomized block design and set 5 soil levels of nitrogen and potassium,and soil N/K were 0.9,0.7,0.6,0.5,0.4,The study was carried out in Agronomy Experimental Station of Shandong Agricultural University.The main results were as follows: 1 Root tuber yield of sweet potato and dry matter accumulation and distributionWhen soil N/K ratio of 0.5 the sweet potato root tuber yield was the highest,soil N/K ratio is low,the yield decreased rather than increased.Effects of soil N/K ratio to root tuber number is not significant.Effects of soil N/K ratio on the yield of sweet potato is mainly affecting the fresh weight.Sweet potato root yield increase is that suitable soil N/K ratio can make the sweet potato plant leaf area and specific leaf weight in root swelling late at a high level.Suitable soil N/K ratio enhance leaf transpiration rate,increased intercellular CO2 concentration,increasing stomatal conductance,a significant increase in photosynthetic rate of function of sweet potato,photosynthetic rates in root swelling period maintained a high level.Suitable for soil N/K ratio can promote to root dry matter transport,improving root inflated rates,improve initial root dry matter accumulation,extension of dilated duration,improve the allocation of harvest in root dry matter,harvest index,and ultimately high root yield.Soil N/K ratio is low,sweet potato leaf area,specific leaf weight decreased transpiration rate decreased photosynthetic rate,photosynthetic capacity is reduced.Soil N/K ratio is low,and root inflated rate,harvest index decrease.2 The key process that affected the transport and distribution of photosynhtates of sweet potatoSuitable for soil N/K ratio is conducive to enhanced source of photosynthate manufacturing capabilities,and the library-side unloading of photosynthetic products.In root inflated early effect dry material by source to library transport of factors main is sucrose by handle to stems vine base.Department of transport,petiole in the sucrose accumulated is limit factors;in root inflated in the late,effect dry material by source to library transport of factors main is by leaves to handle and by stems base to root of sucrose transport,that source end light collection product manufacturing and library end light collection product uninstall are effect dry material to root transport,and stems base to root of sucrose concentration biger,library end uninstall effect more serious.Suitable for N/K ratio decreases basal stem diameter,reduced sucrose concentration in different organs,promoting the transport of dry matter by the source to the library substantially improve end-activity of key enzyme breaks down sucrose SS and AI.Suitable for soil N/K ratio allocation of assimilates to roots increased in proportion,to enter efficiency increased in roots,tubers uninstall capability.Soil N/K ratio is low photosynthate allocation to roots in the reduction,increase in the proportion assigned to the collateral in the stems and leaves,and input efficiency of assimilates to roots declined.3 Absorption and utilization of nitrogen and potassiumSuitable for soil N/K ratio can improve early root inflated accumulation in leaves and petioles nitrogen and potassium,promoting expanded late in the nitrogen,potassium transport,promoting root nitrogen and potassium to assign.Suitable for soil N/K ratio enhance root accumulation of nitrogen and potassium.Increase potassium,potassium decreased productivity.Suitable soil N/K ratio can improve the agricultural utilization of potassium fertilizer,soil N/K ratio is low will reduce the absorption of potassium fertilizer utilization and increases the physiological utilization of potash fertilizer. |
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