| Black soybean(Glycine max(L.)merr)is an economically important leguminous seed crop that is rich in numerous nutritional components,such as anthocyanin,isoflavones,dietary fiber,unsaturated fatty acid,protein and microelements.These components contribute to their various functions,including kidney nourishing blood,heat-clearing and detoxifying,promoting blood circulation to remove blood stasis,improving eyesight,prolonging life and other health care effect.Therefore,black soybean seed is a typical medicine edible food.Current research systemically evaluated the morphology,chemical compositions and the shading-tolerance characteristics of 45 black soybean germplasms,which were collected from southwest China.In this research,we established several methods to analyze the chemical compositions of black soybean seeds;constructed the membership function of soybean plant shading-tolerance characteristics;and screened several high quality black soybean germplasms,which are suitable for the intercropping planting pattern in Sichuan Basin based on multidimensional evaluation index.Meanwhile,the metabolic regulation mechanism of shading-tolerance characteristics of black soybean germplasms was preliminarily discussed,aiming to establish a foundation for the further development of special germplasm resources.The main results of this research were as follows.1.Agronomic characters evaluation of black soybean germplasmsThe analysis of agronomic traits of 14 black soybean germplasms which were introduced to Sichuan Basin showed,the coefficient variations of the bottom pod height,average section length,branch number,effective pod number,the longest branch and yield per plant were more than 45%;those of stem diameter,reproductive growth period and growth period were 22.02%,10.75%and 22.02%,respectively.Most of the correlation among different traits reached extremely significant level(P<0.01)through correlation analysis.Principal component analysis showed,the first principal component reflected the morphological traits of plant;the second principal component reflected the grain size characteristics;and the third principal component reflected the characteristics of yield.Cluster analysis divided the investigated germplasms into three groups:group I with high yield,group II which can be used as forage materials,and group III which can be used as special breeding materials with big seed size.2.Chemical evaluation of black soybean germplasmsThe methods for the quantitative analysis of isoflavones,anthocyanin,fatty acids,total protein,water soluble protein and polysaccharide were established based on high performance liquid chromatography-mass spectrometry(LC-MS),gas chromatography-mass spectrometry(GC-MS)and other technology platforms.The results indicated the mean content of isoflavones of 45 germplasms was 4.061 mg/g on the base of dry seeds,among which cv.CQ13 had the highest content of 7.256 mg/g.For different isoflavones forms,aglycones dominated the mean content of 0.974 mg/g.The content of anthocyanin was averaged as 2.574 mg/g,and cv.E314 had the highest content of 5.206 mg/g.The mean content of fatty acid was 88.829 mg/g,and cv.SCGY possessed the highest contents of total and unsaturated fatty acid(127.795 mg/g and 109.693 mg/g,respectively),while cv.QWT17 had the highest content of saturated fatty acid(19.960 mg/g).The average of soluble protein content was 13.711%,and the highest content was in cv.QWT15(21.207%).The average of soluble sugar content was 12.811%,and CQ13 had the highest content of 22.267%.Average total protein content was 40.915%,and the highest content was in cv.NH20 which was up to 48.507%.These results showed the great differences on chemical parameters among selected germplasms.After introduction,the contents of these chemical compositions showed some differences.The mean content of anthocyanin,isoflavones,total protein and fatty acid were 2.756 mg/g,3.460 mg/g,45.113%and 56.638 mg/g,respectively.The varied characteristics of these quality traits were mainly reflected in isoflavones and anthocyanins.Correlation analysis,which was carried out on the chemical compositions,showed that,total isoflavones were significantly and positively correlated with acetyl isoflavone;significant and positive correlations were also observed among the components of fatty acid.Cluster analysis results showed that,the selected material can be divided into three groups:group ? contained high fatty acid germplasm;group ? materials for breeding high fatty acid black beans;group ? for developing germplasm with high isoflavone,anthocyanins and protein content;group IV contained high isoflavone aglycone germplasm.3.Antioxidant activity evaluation of black soybean germplasmsCommon methods including ferric ion reducing,salicylic acid capturing hydroxyl radicals,DPPH and riboflavin-NBT were used to determine the antioxidant activity of alcohol extract from black soybean seeds.The results showed the mean total antioxidant capacity was 0.019 ?mol/g,and SCPJ17 possessed the highest value of 0.041 ?mol/g.The averaged scavenging rate of free radicals,OH· and O2-· were 54.85%,72.44%and 90.18%,respectively,and cv.QWT31,cv.GZ11 and cv.QWT19 had the highest rate respectively.Correlation analysis showed that,the total antioxidant activity,DPPH and O2-· scavenging ability were significantly and positively related with the contents of anthocyanin and isoflavone.4.Shading-tolerance evaluation of black soybean germplasmsThe comparative analysis of 6 physiological indexes at soybean seedling stage under normal light and shade stress condition showed that,shade stress seriously affected stomatal conductance,transpiration rate,initial fluorescence yield,net photosynthesis,hypocotyl length,stem dry weight and leaf dry weight.The response to shade stress varies with shade-tolerance ability of black soybean and the root parameters such as total root length,root surface area,total root volume,and root dry weight were all showed similar rule as shade-tolerance>moderate shade-tolerance>susceptible germplasms.That's indicated that the shade-tolerance black soybean germplasms have a more developed root system.The variation analysis of 11 shading-tolerance related parameters at monoculture and intercropping showed that,yield per plant,effective pod number and total pod number performed the highest variation coefficient of 251.07%,176.03%and 148.12%,respectively,indicating these material had significant variation in yield characters.Principal component analysis results showed that,the first principal component mainly represented the yield characteristics;the second principal component mainly represented the agronomic characters;the third principal component mainly represented dry matter accumulation ability;the fourth principal component mainly presented the morphological characteristics.Cluster analysis divided the selected germplasms into three categories:the first category represented the shading tolerant germplasms;the second category represented the shading sensitive germplasms;the third category represented moderate tolerant germplasms.The optimal model was D=-0.003 + 0.148SD + 0.102NOB +0.065 YP + 0.021SW.Correlation analysis showed that,plants with higher values of stem diameter,branch number,yield per plant and 100-seed weight were more resistant to shading stress.5.Comparative analysis of chemical compositions of black soybean germplasms grown under sole cropping and relay intercropping systemsThe results of comparative analysis showed that,the contents of total protein,isoflvaones and fatty acid were decreased while anthocyanins increased at different levels in relay intercropping system as compared to sole cropping system.The correlation analysis between chemical compositions and seedling shade-tolerance comprehensive value(D)indicated that isoflavones,anthocyanins and protein were involved in shading-resistance reaction.The correlation analysis of root index and seedling shade-tolerance appraisal index revealed that the root structure of black soybean plants under shading stress was correlated with shading tolerance.As for the aboveground part,photosynthetic rate was the most correlated parameter with shading tolerance.Correlation analysis of the chemical composition and shade resistance comprehensive value(D)showed that acetyl isoflavone,soluble sugar,soluble protein,total isoflavones,G type isoflavones,anthocyanins and fatty acids were involved in shade resistance reaction at later growth stage. |
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