Comprehensive evaluation and screening of forage quality for silage of wild soybean germplasm resources collected from Guangxi

【Objective】To comprehensively evaluate the forage quality for silage of wild soybean（Glycine soja） germplasm resources from Guangxi, identify superior germplasm with excellent silage qualities, and provide original genetic materials for breeding silage-specific forage soybean varieties and enhancing their forage quality. 【Method】A total of 94wild soybean germplasm resources collected from Guangxi were used as experimental materials, and the forage quality for silage of the experimental materials was determined after whole plant mowing at seed filling stage（R6）. The methods of correlation analysis and cluster analysis were applied to assess these quality indicators. Membership function analysis, principal component analysis and a combination of both methods were used for the evaluation on forage quality for silage of the tested materials and screening of superior wild soybean germplasms. 【Result】Crude protein（CP） was extremely significantly negatively correlated with crude fat（CF）（P＜0.01, the same below）, significantly negatively correlated with neutral detergent fiber（NDF）（P＜0.05） and significantly positively correlated with relative feed value（RFV）, dry matter intake（DMI） and relative forage quality（RFQ）. These results indicated that the germplasms with low CF and NDF contents could be selected when selecting the germplasms with high CP, high RFV, high total digestible nutrients（TDN）, and high RFQ. The results of systematic clustering showed that 94 wild soybeans were divided into four categories at Euclidean distance of 20, among which group II included 9 germplasms mainly from Quanzhou County and Xing’an County in Guilin City. This group displayed higher positive forage quality indexes such as CP content（mean value was 22.98%）, RFV（mean value was 133.26）, TDN（mean value was 58.10） and RFQ（mean value was 127.41） as well as lower negative indexes, including CF content（mean value was 21.39%）, ADF content（mean value was 32.31%） and NDF content（mean value was 44.51%）, which indicated that the group II was the germplasm group with excellent forage quality.Comparison using membership function analysis, principal component analysis, and a combination of both methods were conducted to evaluate the germplasm. As a result, ten germplasm resources of wild soybean with multiple or single excellent quality traits for silage were identified, such as GXYSD33, GXYSD10, GXYSD43, GXYSD48 and so on. Among them, GXYSD33 was the superior germplasm with forage quality. Its CP content（28.28%）, RFV（141.84）, RFQ（136.07） and TDN（61.83） were all positive forage quality indicators, ranking the highest of all experimental materials.【Conclusion】The significant and extremely significant correlations among traits of forage quality for silage of wild soybeans lay a foundation for simultaneous improvement of multiple traits. The ten germplasm resources of wild soybean with excellent forage quality for silage selected in this research can be used as ideal genetic materials for breeding and genetic improvement of silage forage soybean varieties.