Studies On The Evolution Of Root Traits Of Soybean Varieties From Different Decades By Using Grafting Technique

During the genetic improvement of soybean cultivars, we were used to pay attention to the agronomic trait,but not root. The results show that the yield increase was due to an increase in biomass,harvest index,leaf area,number of seed number per pod,but reduced in plant height.Root is closely related to the soybean development and yield formation. It will give some incorrect indication to evaluate the function of root by lack of high performance approach.It is difficult to separate the influence, which was caused by root or shoot,because the interaction between shoot and root. This study establishied a science platform which was used to evaluate the contribution of the root by using grafted method,which provided a new method for the root study and evaluate the contribution of soybean root and the root properties from different decades. The main results showed as follows:1The effect of soybean root from different decades on the scion yield was studied by the pot trial and field trial. When ZGDD was used as scion,the soybean roots from different decades had significant impact on biomass of scion(shoot fresh weight、shoot dry weight、stem weight). Shoot fresh weight、shoot dry weight、stem weight decreased with year of release, shoot dry weight was in a significant negative correlation with year of release in field trial. The contribution ability of root to biomass reduced with year of release.As while as ZH39was used as scion,the soybean root from different decades has significant impact on yield components and yield. Correlation were performed based on yield components and year of release. The results showed that yield components and yield were in a significant negative correlation with year of release in field trial and pot trial. Seed weight per plant decreased with year of release. The contribution ability of root to yield reduced with year of release.2The pot trial and field trial were carried out to research the effect of soybean cultivar root from different decades on the agronomic characters of scion. When ZGDD was used as scion,the soybean roots from different decades had significant impact on plant height、main stem node number、stem width of scion.Plant height、main stem node number、stem width were in a negative correlation with year of release in pot trial, only main stem node number was in a significant negative correlation with year of release. Plant height、main stem node number、stem width were in a significant negative correlation with year of release in field trial.As while as ZH39was used as scion, plant height main stem node number、branch number were in a negative correlation with year of release in pot trial, only branch number was in a significant negative correlation with year of release in pod trial,and plant height was in a significant negative correlation with year of release in field trial3The field trial were carried out to research the effect of soybean cultivar from different decades on the protein content and oil content. The protein content of soybean from Yellow-Huai-Hai Rivers Valley decreased with year of release,while the oil content significantly increased. The soybean cultivar from different decades were acted stocks, the protein content of scion significantly increased with year of release,while oil content decreased.4The effect of root on the maturity of scion was studied by the pot trial and the field trial. The results showed that the soybean roots have significant impact on days from VE to R1. Correlations were performed based on maturity traits and year of release. VE-R1and VE-R7were in a negative correlation with year of release. Days of VE-R7was became shorter.The soybean roots have significant impact on days from VE to Rl,plant height, main stem node number of the Middle-late-maturing scion. Regression analysis of VE-R1and year of release showed that soybean The days from VE toRl decreased with year of release. It showed that the floral stimuli maybe exsit in cotyledons.5The evolution of root traits were studied by pot trial and the field trial. The results showed that the soybean cultivar from different decades have significant impact on tap root length, number of lateral root, root/shoot ratio, root dry weight. The root dry weight increased with year of release, when the soybean cultivar from different decades were used as stock(scion), the graft-self treatment showed the same result. Root dry weight has a significant positive effect on shoot fresh weight, shoot dry weight,Stem width.6It invented a new method to research the root traits by using grafting technique.In this study, the root integer was studied as a "black box". This method improved on the root experiment. It could be used to research on the root-shoot relationship.