Multivariate Statistical Analysis And Germplasm Innovation Of Ornamental Pepper Germplasm Resources

With the development of urban sightseeing agriculture and home horticulture industry,ornamental pepper,which has peculiar fruit type and consumption function,is increasingly respected by consumers.The demand for diversity of ornamental pepper germplasm resources is increasing day by day.At present,China lacks ornamental pepper varieties with independent intellectual property rights.There are few reports on analysis,evaluation and systematic germplasm innovation of ornamental pepper germplasm resources at home and abroad.In this study,45 agronomic traits of 39 ornamental pepper germplasm resources collected by the research group are analyzed by multivariate statistics,and the germplasm resources are evaluated and analyzed.According to the evaluation results,8 high-quality materials are selected as parents,and their heterosis and combining ability are analyzed.A group of positive and negative cross combinations with excellent comprehensive performance are selected,and F2 generation population is configured to make statistical analysis on the genetic segregation status of ornamental traits.The results are as follows:1.Among the 18 quantitative traits of 39 ornamental pepper germplasm materials,the largest difference is the number of fruits per plant,plant width and plant height,and there are great differences in plant type traits among various germplasm materials.The distribution range of coefficient of variation is between 25% and 99%,with an average value of 46%.The largest coefficient of variation is fruit diameter,while the lowest coefficient of variation is fruit stalk length.Among the quality traits,the diversity index of pericarp color is the highest,while the diversity index of fruit surface luster and fruit growth mode is the lowest.Correlation analysis of agronomic traits shows that in terms of plant morphology,there is a significant positive correlation between plant height and plant width,main branch length,leaf length,leaf width and leaf spacing(P < 0.05).There is a very significant positive correlation between plant width and branch series,branch type and number of fruits per plant(P < 0.01).In terms of mosaic morphology,there is a very significant positive correlation between corolla color,young fruit color,green ripe fruit color and pericarp color(P < 0.01).There is a very significant positive correlation between leaf length and leaf width,petiole length,single fruit weight,fruit stalk length and fruit stalk diameter.There is a very significant positive correlation between leaf color and corolla color,young fruit color and green ripe fruit color(P < 0.01).In terms of fruit morphology,there is a significantpositive correlation between fruit length and fruit stalk length(P < 0.05).There is a very significant positive correlation between pericarp color and fruit diameter(P < 0.01).2.Principal component analysis shows that the cumulative contribution rate of the first seven principal components reached 65.35%.It can represent most agronomic trait information,including leaf factor,flower and fruit color factor,plant type factor,fruit factor and other ornamental traits.Further cluster analysis shows that 39 materials can be divided into 3 subcategories at chi-square distance of 2.35,namely,dwarf developing small fruit subcategory,semi-erect multi-fruit subcategory and purple subcategory.The membership function analysis method shows that among 39 germplasm materials,the ornamental value of ornamental pepper is ranked according to the D value of various germplasm materials.Among them,'Habanero Lemon' has the largest D value and the highest comprehensive ornamental value.Heterosis of ornamental pepper is common.Among 56 F1 combinations,98% of the combinations show super-medium heterosis in plant type traits.The average heterosis of medium parents in plant type traits is positive,and the order from large to small is: plant height > branch series > plant width > main branch length > lateral branch number > initial flower node position.86% of the combinations show super-parent heterosis in plant height,and the average value of super-parent heterosis is: plant height >plant width > series > main stem diameter > initial flower node position > main branch length > lateral branch number.In terms of mosaic and leaf characters,57% of the combinations show medium-parent heterosis in leaf length and 95% show medium-parent heterosis in flower diameter.The order of medium-parent heterosis from large to small is: number of flowers per plant > leaf width > anther length > petiole length > petal length > flower diameter > style length > number of flowers in axil of single node leaf > leaf length > leaf spacing.68% of the combinations show super-parent heterosis in the number of flowers per plant,and the order of super-parent heterosis is number of flowers per plant >anther length > flower diameter > leaf width > stigma length > petal length > petiole length > leaf length > number of flowers in axil of single node leaf > leaf spacing.96% of the combinations show mid-parent heterosis in the number of fruit per plant,and the order of mid-parent heterosis index is:number of seeds per fruit > number of fruit per plant > weight of single fruit > length of fruit stalk >diameter of fruit > length of fruit stalk > diameter of fruit stalk > thickness of pulp.64% of the combinations show super-parent heterosis in fruit setting number per plant,and the order of super-parent heterosis is: seed number per fruit > fruit setting number per plant > fruit stalk length > fruit stalk diameter > fruit diameter > single fruit weight > pulp thickness.3.The analysis of parent-child correlation and regression shows that the correlation coefficients of 20 main traits between parents and the first generation of hybrids reach significant or extremely significant level,and it is feasible to predict the performance of the first generation of hybrids by using the size of parents.The first generation of hybrid is affected by the number of fruits per plant and the comprehensive influence of the three parent values of high school and low school,especially the middle parent value.The plant height,main branch length and lateral branch number of F1 generation are greatly affected by the average value of parents.In order to increase the plant height and the number of lateral branches in the first generation of hybrid,parents with larger plant height or more lateral branches should be selected,and attention should be paid to increase the average value of both parents.The leaf size and flower size of F1 generation are greatly affected by the average value of parents,especially the high-value parents.Attention should be paid to increase the average value of parents in order to improve the character size of leaves and flowers,especially the high-value parents with larger values,so as to improve the leaf and flower size of F1 generation.The analysis of combining ability shows that the general combining ability values of 8 parent materials show great differences in different traits.P7 has the largest general combining ability value of fruit number per plant,and P8 has the largest general combining ability value of fruit length.P8 is suitable as a parent for breeding large fruit varieties and increases the fruit size of the hybrid,while P7 can be used as a parent for breeding rich fruit varieties.In terms of plant traits,P14 is suitable for breeding varieties with higher plant height and more lateral branches,while P9 is suitable for breeding varieties with wider plant width and large main stem diameter.In terms of flower and fruit traits,P7 can be used as a candidate parent for breeding varieties with abundant flowers,while P9 is suitable for breeding varieties with large leaves and flowers.The combinations P6 × P15,P6 × P22 and P7 × P23 all show good special combining ability effect values in 9 fruit traits,which can be used as benign combination materials for breeding excellent fruit traits.P8 × P22 and P9 × P8 can be used as good combinations for breeding ornamental pepper with higher plant type.P 6 × P 15 shows positive values in 10 agronomic traits,which shows larger plant width and stout growth potential,and more compact leaves and plant types,which is the best combination.4.There are significant differences in agronomic traits of plant type and leaf type between F1 and F2 generations when parents with oval leaves cross with parents with lanceolate leaves,and when parents with developing types cross with parents with erect types.Parents P6 and P15 have significant differences in leaf length,leaf width,petiole length,plant height,lateral branch number and other indexes.According to the results of the segregation ratio of F2 generation population traits of its positive and negative cross combinations P6 × P15 and P15 × P6,combined with chi-square test,it can be concluded that the cluster traits of ornamental pepper fruits are recessive to the solitary traits.Finite branches are recessive to infinite branches.The spreading plant type has recessive epistatic effect on the erect plant type.Leaf shape lanceolate has recessive epistatic effect on oval shape.