| With the acceleration of land transfer and the adjustment of planting structure,the main sugar beet planting area in Inner Mongolia were gradually shifted to cold and arid region,most farmland of these areas have been used the drip irrigation facilitie sunder mulch.Influenced by traditional ideas,local farmers used excessive nitrogen fertilizer and less even no potassium fertilizer,resulting in nutritional imbalance,which are main factors to restrict the yield and quality improving of sugar beet production.With the starting pointing of scientific fertilizer application and low cost but high efficiency,this paper has carried out a series of studies on the cultivation techniques of drip irrigation under mulch.The effects of potassium on nutrient uptake and utilization,photosynthetic characteristics and nitrogen metabolism were systematically analyzed,which specified the influence of potassium fertilizer on sugar beet yield and quality and proposed reasonable fertilizing amount.The research aimed to reveal the physiological basis related to potassium and sugar beet production,further can provide a scientific basis and reference for the reasonable fertilization of sugar beet.The main results are as follows:(1)Appropriate potassium application can promote the absorption and utilization of nitrogen,phosphorus and potassium nutrients in sugar beet with drip irrigation under membrane.The appropriate amount of potassium increased the root,petiole and leaf nitrogen content at early growth stages in sugar beet,and the nitrogen absorption of various organs and yield was a very significant positive correlation.When the amount of potassium applied at 12kg/mu,the ratio of phosphorus uptake was significantly higher than that of non-applying and excessive application of potassium fertilizer(24kg/mu).The potassium contentin organs decreased with the sugar beet growth process.With the increase of potassium application rate,the potassium content of each organ and the potassium uptake of single plant increased.The potassium content had a great influence on the accumulation of potassium in the late growth stage.Physiological utilization rate of potassium was highest with potassiumapplication 12kg/mu,up to 103.4kg/kg.(2)Potassium could increase the photosynthetic performance of sugar beet with drip irrigation undermulch,such as plant height,leaf number and leaf area index.The application of potassium fertilizer 12kg/mu,18kg/mu and 24kg/mu increased the net photosynthetic rate,which mainly affected by RuBPCase activity,followed by stomatal conductance.Appropriate amount of potassium increased the sugar beet yield in root,petiole and leaf dry weight.On the contrary,excessive application of potassium fertilizer will decrease the beet sugar content because it inhibit the transport of photosynthetic products to the root,so the dry matter distribution of the roots decreased.(3)Potassium promoted the activity of NR and GS,the content of soluble protein in root and leaf,and the yield of sugar beet,which indicated that potassium could affect the yield by regulating the nitrogen metabolism of sugar beet.(4)Appropriate potassium fertilizer application promoted the yield and quality of sugar beet with drip irrigation under mulch.The highest yield can get by 18kg/mu potassium application,the highest sugar content with 6~12kg/mu and the largest economic benefitswith 12kg/mu.When the amount of potassium was more than 12kg/mu,the content of K~+and Na~+increased in the root of the harvest.When the amount of potassium was more than 18kg/mu,the content of a-amino acid in the root was increased.(5)According to the effects of potassium on sugar beet yield,quality and economic benefits,the recommended potassium fertilizer ratewas 12kg/mu in the main sugar beet planting area in Inner Mongolia... |
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