Changes Of Root Bleeding Sap Component And Its Correlations With Yield Of Soybean Cultivars With Different Released Years

Many reports had showed about changes of agronomic traits and physiological traits of soybean cultivars with different released years, it was researched that changes of weight and substance content of root bleeding sap and its correlation with leaf net photosynthetic rate and yield in recent years. But about changes of mineral(Ca2+, K+ and Na+)content and endogenous hormone(ZT and ABA)content of root bleeding sap in the genetic improvement process of soybean cultivars have not been reported, especially about their correlation with the net photosynthetic rate, root activity,plant biomass and yield is still not very clear. This study used soybean varieties bred in Jilin Province in 1923-2009 to research the evolution characteristis of root mineral content and endogenous hormones content, and analyze the relationship of changes of mineral content and endogenous hormones content between the net photosynthetic rate, root activity, plant biomass and yield. Aimed to clarify the evolution law of mineral content and endogenous hormones content of root bleeding sap in the genetic improvement of soybean in Jilin Province, and reveals the role of regulation and nutrition of mineral and endogenous hormones to Soybean growth and development,to provide the theoretical basis for the the soybean varieties improvement in Jilin Province.The experiment was conducted in 2012 and 2014,and chose the 30 soybean varieties bred from 1923 to 2009 in Jilin Province. Measured mineral content and endogenous hormones content of root bleeding sap,the net photosynthetic rate, root activity,plant biomass and yield at R2,R4,R6,R7 growth stages, and further analyzed the relationship between them, the results of the study show that:1. With the genetic improvement and yield of soybean varieties increased, calcium ion(Ca2+) content of root bleeding sap was increased at 4 growth stages, and was significantly positive correlated with released year at R6 stages,and was not significant correlated at rest 3growth stages. With growth progress, Ca2+ content of soybean varieties bred showed a single peak curve in Before 1950 s, 1960s-1980 s and 1990s-2000 s three period, and reached the maximum value in R4 stages.The soybean grain yield, aboveground dry matter weight and Ca2+ content of root bleeding sap had significant positive correlation at R2 stages. The soybean grain yield, aboveground dry matter weight, root dry matter weight, the net photosynthetic rate, root activity and Ca2+content of root bleeding sap had significant or extremely significant positive correlation at R4 stages. The soybean grain yield, root activity and Ca2+ content of root bleeding sap had signifycant positive correlation at R6 stages. The soybean grain yield, the net photosynthetic rate and Ca2+ content of root bleeding sap had significant positive correlation at R7 stages. Ca2+ content of root bleeding sap was closely related to each index at R4 stages.2. With the genetic improvement and yield of soybean varieties increased, potassium ion(K+) content of root bleeding sap was increased at 4 growth stages, and was significantly or extremely significant positive correlated with released year at R4,R6,R7 stages,but they was not significant correlated at R2 stages. With growth progress, K+ content of soybean varieties bred showed a single peak curve in Before 1950 s, 1960s-1980 s and 1990s-2000 s three period, and reached the maximum value in R4 stages.Each index and K+ content of root bleeding sap had not significant positive correlation at R2 stages. The soybean grain yield, aboveground dry matter weight, the net photosynthetic rate,root activity and K+ content of root bleeding sap had significant positive correlation at R4 and R6 stages. The soybean grain yield, root activity and K+ content of root bleeding sap had significant positive correlation at R7 stages. In addition to K+ content of root bleeding sap was closely related to root activity at R4 stages, K+ content of root bleeding sap was closely related to the rest index at R6 stages.3. Sodium ion(Na+) content of root bleeding sap was negative correlated with released year at R2 and R7 stages, and reached the extremely significant level at R2 stages, but no significant correlation at R7 stages. sodium ion(Na+) content of root bleeding sap was positive correlated with released year at R4 and R6 stages, and reached the extremely significant level at R6 stages,but no significant correlation at R4 stages. With growth progress, Na+ content of soybean varieties bred had increased continuously in before 1950 s and 1990s-2000 s, and reached the maximum value in R7 stages. With growth progress, Na+ content of soybean varieties bred was first increased, then decreased and then increased in 1960s-1980sThe soybean grain yield and Na+ content of root bleeding sap had a significant negative correlation at R2 stages. The soybean grain yield, aboveground dry matter weight and Na+content of root bleeding sap had a significant positive correlation at R4 and R6 stages, and closely related at R6 stages.4. With the genetic improvement and yield of soybean varieties increased, cytokinin(ZT)content of root bleeding sap was increased at 4 growth stages, and was significantly positive correlated with released year at R2, R4 and R7 stages, but they was not significant correlated atR6 stages. With growth progress, ZT content of soybean varieties bred showed a single peak curve in before 1950 s, 1960s-1980 s and 1990s-2000 s three period, and reached the maximum value in R4 stages.The soybean grain yield, the net photosynthetic rate, root activity and ZT content of root bleeding sap had significant positive correlation at R2 and R4 stages. The soybean grain yield,root activity and ZT content of root bleeding sap had significant positive correlation at R6 stages.ZT content of root bleeding sap was closely related to root activity at R2 stages, grain yield, and ZT content of root bleeding sap was closely related to the net photosynthetic rate at R4 stages.5. With the genetic improvement and yield of soybean varieties increased, abscisic acid(ABA) content of root bleeding sap was increased at 4 growth stages, and was significantly positive correlated with released year at R2 and R7 stages, but they was not significant correlated at R4 and R6 stages. With growth progress, ABA content of soybean varieties bred had increased continuously in before 1950 s, 1960s-1980 s and 1990s-2000 s three period, and reached the maximum value in R7 stages.The soybean grain yield, aboveground dry matter weight and ABA content of root bleeding sap had significant negative correlation at R2 stages. The net photosynthetic rate and ABA content of root bleeding sap had significant negative correlation at R6 stages. The soybean grain yield, aboveground dry matter weight, root dry matter weight, root activity and ABA content had significant negative correlation at R7 stages, and was closely related.In summary, the genetic improvement of soybean cultivars significantly increased ZT content of root bleeding sap at R2 stages, Ca2+,K+ and Na+ of root bleeding sap at R6 stages, K+and ZT of root bleeding sap at R4 and R6 stages.The genetic improvement of soybean cultivars significantly decreased Na+ and ABA of root bleeding sap at R2 stages, ABA of root bleeding sap at R7 stages. To illustrate, genetic improvement of soybean changed physiological characters of plant root system, promoted the absorption of mineral elements(Ca2+,K+)and plant growth hormone(ZT) synthesis, which quickly reached to a higher content in early growth period, and keeped the content stability at critical period of growth(R4-R6) to keep the content stability.It improved the capacity of transport them to the plant upper part, contributed to the growth of soybean and seed formation, improved the anti-aging ability, delayed abscisic acid synthesis rate of modern cultivars, delayed the plant senescence process.In production practice, we should pay attention to improve root growth, enhanced root dry matter accumulation, increase the ability to absorb Ca2+,K+ and growth hormone(ZT) synthesis,reduce Na+ supply at R2 stage. Keep high Ca2+ and K+ supply to plants, high root ZT synthesis and transport capacity at R4 and R6 stage. Keep high K+ supply to plants and Maintain high rootactivity at R7 stage. Suppression and delay root ABA synthesis at R6 and R7 stages. They plays an important role to increase yield, because they can improve soybean leaf photosynthetic performance, delay plant senescence, promote soybean dry matter accumulation and transport to seed.