Effect Of Potassium Application On Yield And Quality And Nutrient Absorption Of Sweet Potato

Potassium can influence the formation of yield and quality of crop,It was known that sweet potato is typical of potassium crop. This experiment was to explore the effect of K application on yield and quality and nutrient element of sweet potato,to improve the utilization rate of K fertilizer. This experiment was carried out at the experimental station of Tai’an Shandong province in2012and Anqiu Shandong province in2013.The varieties of sweet potato were Jiheil,Ningzil,Yanshu25and Taizhong6. The main results were as follows:1. Potassium application can improve the fresh yield, but the effects of potassium application were different among different sweet potato cultivars. Comparing with the high potassium treatment, the low potassium treatment had higher amount of increase in production of purple sweet potato; the edible-type sweet potato had a totally different trend, the high potassium treatment had higher amount of increase in production. Among the four varieties of sweet potato, Taizhong6was more sensitive to potassium fertilizer application. The amount of increase in production of high potassium treatment of Taizhong6was120.86%. At the same time, Jiheil was the most unsensitive to potassium fertilizer application.The most increase rate of potassium application treatment of Jiheil was19.88%. With the test conditions, the increasing trend for fresh potato of potassium application appeared as Taizhong6>Ningzil>Yanshu25> Jiheil.2. Potassium application can improve the fresh weight of single potato, the storage root lumps per plant, but there were differences between different varieties. The increase of fresh yield was mainly from the increase of fresh weight of single potato. Potassium application can improve the number of the storage root lumps per plant, but there were not markedly differences between different potassium application treatments. Potassium application increased dry matter of single plant and distribution proportion of dry matter in subterranean part; there were different effects of potassium application among different cultivars.3. The T/R was reduced rapidly along with the growth of the sweet potato. Potassium application can reduce the T/R of sweet potato, there was more influence at the early stage of growth than at the late growth stage.There exist certain differences between different varieties.The T/R of Ningzil,Yanshu25was bigger than that of Jiheil,Taizhong6. The decrease of T/R ratio helped to prevent the stem leaf moderate growth and to increase photosynthesis product distribution in subterranean part.4. Potassium application can improve potassium, phosphorus and nitrogen accumulation of sweet potato, but there were differences between different varieties. The potassium accumulation of four cultivars from high to low appeared as Yanshu25>Taizhong6>Jiheil>Ningzil. Except Ningzil,the potassium accumulation of other three cultivars was increasing along with the increased amount of potassium application. The amount of potassium accumulation in sweet potato root also increases with the increased amount of potassium application,as well as the amount of phosphorus and nitrogen accumulation in the root.5. Potassium application influence the proportion of nutrient elements of sweet potato. Potassium application can improve the K/N, K/P, K/Ca ratio in sweet potato root. Potassium application can also improve the Ca/Mg ratio,it showed that there was different antagonism effect between calcium and magnesium with potassium application.6. Potassium application significantly increased soluble sugar content of Jiheil and Yanshu25, but reduced starch and protein content. Potassium application also influence the proportion of amylose and amylopectin in sweet potato root,but there were differences between different cultivars. Potassium application can improve anthocyanins content in root of Jiheil.