Effects Of Phosphorus And Potassium On Potassium Accumulation, Distribution And Culm Lodging Resistance Of Relay-planting Soybean

As a high-efficiency and new cultural mode,relay-planting soybean system is dominant in southern China.However,studies on relay-planting soybean are so defective that restrict the application and extension of this new mode.This experiment was carried out to study the effects of different phosphorus and potassium managements on relay-planting soybean's potassium accumulation,distribution and lodging resistance of culm,yield and seed quality used limited-pod type soybeans(Gongxuan No.1) in relay-planting system of wheat/maize/soybean.The main results showed as follows:1.Reasonable application of phosphorus and potassium is beneficial to improve morphology of basal internode and enhance the culm's performance of lodging.Potassium application significantly affects the ability of culm lodging of relay-cropping soybean.At the same levels of phosphorus,as the application amount of Potassium increased,the length of basal internode and main culm decreased,but the diameter of basal internode,dry weight,content of cellulose and lignin,carbon nitrogen ratio and CLRI were opposite.The results showed the CLRI was positively correlated with diameter of basal internodes,dry weight of internode and mechanical strength.At the same time,CLRI was negatively correlated with length of basal internode and total length of internode.Proper phosphorus application(P₂O₅ 0～17 kg·ha^-1) enhanced the ability of culm lodging of relay-cropping soybean,but the high levels of phosphorus(P₂O₅ 25.5 kg·ha^-1) showed the opposite.As an comprehensive index,CLRI is available to evaluate culm lodging resistance of relay-planting soybean.2.Reasonable application of phosphorus and potassium is beneficial to improve the dry matter accumulation and transfer of the relay-cropping soybean.The total amount of dry matter followed the Logstic growth curve under the different levels of phosphorus and potassium,but change the indicators of maximum growth rate and its days of the emergence under the application of phosphorus and potassium.As the amount of potassium application increased,the dry matter accumulation,transfer rate and contribution rate increased.Dry matter accumulation,transfer rate and contribution rate increased with the phosphorus application increased,until phosphorus application amount reached the threshold value(P₂O₅ 25.5 kg·ha^-1).When the amount of phosphorus was 0～17 kg·ha^-1,increased the potassium can improve the amount of dry matter output and the contribution rate of dry matter from Vegetative organs to legume.3.Proper application of phosphorus and potassium can promote the potassium accumulation and transfer of relay-planting soybean.The trend of dynamic changes of potassium accumulation amount was the same as the trend of dry matter accumulation amount,they showed exponential growth irreversible.The potassium application significantly affected the potassium accumulation amount of relay-planting soybean,the treatment of potassium(K₂O 112.5 kg·ha^-1) was highest.Potassium accumulation amount increased first and then reduced with the increasing of application of phosphorus,the amount of phosphorus(P₂O₅) 17 kg·ha^-1 was the highest.The output rate of the vegetative organs showed:the root was highest,the leaves was second,the stem was minimum.In the condition of proper P application(P₂O₅ 0～17 kg·ha^-1),the amount of potassium output and output rate from Vegetative organs to legume increased as the potassium application increased.4.Reasonable application of phosphorus and potassium improved the efficiency of potassium.The treatment of potassium reduced the uptake and utilization of application of potassium,but increase phosphorus can improve the uptake and utilization,production efficiency of potassium at the same levels of application of potassium.5.Under the reasonable level of phosphorus(P₂O₅ 0～17 kg·ha^-1),increased the amount of potassium can improve the yield of relay-planting soybean,the amount of phosphorus (P₂O₅ 25.5 kg·ha^-1) reduced output relatively.Contrasting by the CK(P₂O₅ 0 kg·ha^-1 and K₂O 0 kg·ha^-1),the other treatment increased the number of pods per plant,grain-filling rate and grain yield,the treatment of phosphorus and potassium application was.the greatest,when the amount of phosphorus and potassium application were 17 kg·ha^-1 and 112.5 kg·ha^-1 respectively,the maximum yield of relay-planting soybean was 2832.04 kg·ha^-1,which was higher 28.55%than CK(P₂O₅ 0 kg·ha^-1 and K₂O 0 kg·ha^-1).6.The treatment of phosphorus application can increase the protein and crude fat content of soybean,the treatment of potassium application increased grain protein content,but the crude fat content decreased significantly.Increase the amount of phosphorus was beneficial to improve the accumulation of grain protein when the amount of potassium(K₂O) was 0～75 kg·ha^-1,but when the amount of Potassium(K₂O) was 0 kg·ha^-1,which was beneficial to improve the crude fat of grain.In conclusion,considering the ability of lodging resistance,dry matter production, regulation of Potassium accumulation and distribution,yield and quality,the proper level of phosphorus application(P₂O₅ 17 kg·ha^-1) and potassium application(K₂O 112.5 kg·ha^-1) could reach the best effect.