| Amaranthus cruentus is an annual C4 herb of the family Amaranthaceae.It has the characteristics of well-developed root system,fast growth,high yield and rich nutrition.It is a food and feed dual-purpose crop.In this study,the germplasm resources of A.cruentus collected and preserved by the research group were used to investigate and analyze the diversity of A.cruentus from the phenotypic level under field conditions.The primary core germplasm group was analyzed and evaluated,and the forage quality of the core germplasm group was analyzed and evaluated,which provided theoretical basis and practical guidance for the protection,development and utilization of A.cruentus germplasm resources.The main research results are as follows:The results of the investigation and analysis of 19 phenotypic traits of 236 A.cruentus germplasm resources showed that the average coefficient of variation of each trait was greater than 35%.The smallest main inflorescence branched type.Among the quantitative traits,the highest variation coefficient was the number of main stem branches,with a variation range of 0～15;the lowest variation coefficient was plant height,with a variation range of 91.1 cm～235.3 cm.The results of correlation analysis showed that there were different degrees of correlation between the phenotypic traits.Among them,the main inflorescence color showed a significant positive correlation with leaf vein color,petiole color,and stem color;plant height was significantly positively correlated with stem diameter,leaf length,leaf width,and fresh weight per plant;the number of main stem branches was significantly correlated with Plant height,stem diameter,leaf length,and leaf width were significantly negatively correlated;the main inflorescence branching type was significantly negatively correlated with leaf shape,leaf surface color,midrib color,and petiole color at maturity.The results of cluster analysis of phenotypic trait indicators showed that 19 phenotypic traits were divided into 4 groups when the Euclidean distance was 1.1,and there was a similar degree of variation among the groups.Based on the phenotypic traits of A.cruentus,using grouping and stepwise clustering methods,16 sampling schemes formed under 4 sampling ratios and 4sampling scales were compared.Finally,83 core germplasms were obtained by constructing 35% sampling scale under the square root ratio.The variation rate of variation coefficient,the range coincidence rate and the phenotypic retention ratio were 106.31%,95.83% and 94.70%,respectively.The phenotypic genetic diversity is preserved in the core germplasm,and the core germplasm has achieved a good construction effect and can represent the phenotypic genetic diversity of the original germplasm.The quality of the core germplasm in A.cruentus was evaluated by using the general nutrient index of feed routine,and each quality trait showed rich genetic variation.The variation ranges of crude protein,crude fat,crude fiber,crude ash and nitrogen-free extract under dry matter conditions were 9.09%～21.21%,0.67%～3.72%,17.24%～36.99%,11.07%～17.66%,32.31%～49.91%.In addition,the variation ranges of neutral detergent fiber,acid detergent fiber and relative feeding value were 30.61%～58.82%,19.31%～36.95%,and 96.58～224.40.Comprehensive correlation analysis and principal component analysis of phenotypic traits and forage quality indicators,selecting seven tables including plant height,leaf length,leaf width,number of main stem branches,main inflorescence length,main inflorescence branch number,and fresh weight per plant.Membership function analysis was carried out for morphological traits and five quality indicators of crude protein,crude fat,crude ash,nitrogen-free extract,and relative feeding value,and 83 core germplasms were comprehensively evaluated.The results showed that the germplasm resource originating in Mexico No.839 and the germplasm resources originating in Nigeria No.748 and 746 had the best comprehensive traits of phenotype and quality. |
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