Screening High Potassium Efficiency Potato Genotypes And Physiological Responses In Different Potassium Level

To explore the difference of potassium uptake and utilization efficiency of Potato Varieties,classify different types of potassium utilization,and provide theoretical and technical support for the selection of potato varieties with high efficiency of potassium utilization,Pot experiment and field experiment were conducted to study genotypic variation for potassium content,yield,potassium uptake and utilization efficiency with low potassium level(K₇₅)and high potassium level(K₃₀₀),and used cluster analysis to divide 20 potato genotypes into four types.Then,through pot experiment,Huayu 5 and Zhongshu 19 were selected to studied agronomical and physiological response under 5potassium levels,and the mechanism of potassium nutrition difference between two genotypes of potato was discussed.The main results are as follows:1、The indicators related to potassium uptake and utilization efficiency at two potassium levels were significantly different among potato genotypes.Variation existed among genotypes in Yield,plant potassium content,tuber potassium content,potassium uptake efficiency,potassium utilization efficiency and potassium harvest index under two potassium level.2、K uptake efficiency had significant positive correlation with plant K content at low k level（P<0.01）,and had positive correlation with tuber K content at high K level(0.529^**,K₇₅ and 0.300*,K₃₀₀).K use efficiency had significantly negative correlation with plant K content at low k level(0.523^**,K₃₀₀).3、Basing on tuber yield at low potassium level and relative yield,we classified potassium use efficiencies of 20 potato varieties into four types:double high efficiency,low potassium and high efficiency,high potassium and high efficiency,double low efficiency.The representative double high efficiency types are qianyu 6 and chuan 117,and the representative low potassium and high efficiency types are Huayu 5 and Zhengshu5.4、At the later stage of growth,the fresh weight of potato plants of two different genotypes increased first and then decreased with the increase of potassium application level.At harvest stage,the fresh weight of Huayu 5 was the highest at the K application level of 10 g·plant^-1,with a weight of 265.52g,while Zhongshu 19 was the highest at the K application level of 15 g·plant^-1,with a weight of 470.88g.At the early stage of growth,the fresh weight of Huayu 5 was higher than that of Zhongshu 19 for.In the later stage,the fresh weight of Zhongshu 19 was significantly higher than Huayu 5.5、The leaf area per plant of potato genotypes with different potassium efficiency increased first and then decreased.The leaf area of Huayu 5 began to decline when at the K application level of 10 g·plant^-1 reached the highest value（65.30 cm²）,while Zhongshu19 reached the highest value（93.06 cm²）at the K application level of 15 g·plant^-1.The effect of potassium on the chlorophyll content of potato leaves was different.The contents of chlorophyll a,chlorophyll b and total chlorophyll of two potato varieties with different potassium efficiency were the highest at the K application level of 10 g·plant^-1.The content of chlorophyll a,chlorophyll b and total chlorophyll of Huayu 5 was the lowest at no potassium level,while that of Zhongshu 19 was the lowest at the K application level of 20 g·plant^-1.6、The net photosynthetic rate of potato genotypes with different potassium efficiency first increased with the increase of potassium application level,and reached the highest at the K application level of 10 g·plant^-1(Huayu 5 was 18.09μmol·m^-2·s^-1,Zhongshu 19 was 15.12μmol·m^-2·s^-1),and then decreased with the increase of potassium application level.The changes of stomatal conductance and transpiration rate of Huayu 5were basically consistent with the changes of net photosynthetic rate.Zhongshu 19 had the highest stomatal conductance and transpiration rate at the K application level of 5g·plant^-1.7、The content of soluble sugar in leaves and tubers of Zhongshu 19 was the highest at no potassium level,which was 25.44mg·g^-1 and 29·42mg·g^-1 respectively.With the increase of potassium application level,the content of sucrose in leaves and tubers of Zhongshu 19 decreased gradually.The content of sucrose in the leaves and tubers of Huayu 5,a low-K and high-efficiency potato variety,increased at first and then decreased with increasing potassium treatments.And the content of sucrose in the leaves reached the highest 29.32 mg·g-1 at the K application level of 5 g·plant^-1,while the content of soluble sugar in the tubers increased slowly with the increase of potassium application level,and decreased at the K application level of 15 g·plant^-1.8、The change trend of potassium utilization efficiency among different genotypes of potassium efficiency was not consistent with the increase of potassium application level.The agricultural utilization efficiency of Huayu 5 first increased with the increase of potassium level,reaching the highest value at the K application level of 15 g·plant^-1,20.93 kg·kg^-1,and dropped to 16.02 kg·kg^-1 at the K application level of 20 g·plant^-1.The agronomic utilization efficiency of Zhongshu 19 increased slowly with the increase of potassium application level,with the lowest value of 14.26 kg·kg^-1 and the maximum value of 22.06 kg·kg^-1.9、The K uptake efficiency of different genotypes of potato decreased with the increase of K application level.The maximum and minimum K uptake efficiency of Huayu 5 were 26.90%and 5.13%,respectively.The highest and lowest K uptake efficiency of Zhongshu 19 were 37.15%and 11.67%,respectively.The potassium uptake efficiency of Zhongshu 19 was higher than Huayu 5,and the difference was the biggest at K3 level.10、The yield of Zhongshu 19 and Huayu 5 increased at first then decreased with the increase of potassium application level.The highest yield of Zhongshu 19 and Huayu5 were potassium application level at 225kg·hm^-2 and 150kg·hm^-2.The trend of potato yield changing with K supply level was fitted by binary first-order equation.Huayu 5reached the highest yield at the K application level of 159.45kg·hm^-2 and Zhongshu 19reached the highest yield at the K application level of 281.4kg·hm^-2.