Comprehensive Evaluation Of Muskmelon Germplasm Resources

Cucumis melo is one of the most important fruits in the world,and its breeding plays an important role in promoting agricultural production.Germplasm resources are the basis of breeding.Comprehensive evaluation of germplasm resources is of great significance to the breeding of new varieties of muskmelon and the development of this industry.This study was based on the important characters of muskmelon germplasm with thick skin,followed the observation of growth period as the main line,investigated the occurrence of field diseases,determined the important indexes of mature fruits,analyzed the differences of germplasm with different methods,comprehensively evaluated 141 muskmelon germplasm with thick skin,and finally screened out the good germplasm.The main research results are as follows:1.According to the observation of the growth period,the fruit development period of different germplasm varied greatly,with the shortest 31d(SL104)and the longest 55d(SL30 and 2020T19),and the range was 24 d.The shortest growth period was 68d(SL240),the longest was 101d(SL20),and the range was 33 d.The relative growth rate of vegetative growth and reproductive growth in the whole growth period showed an S-shaped change.141 thick-skin muskmelon materials could be divided according to the whole growth period,among which 34 early maturity germplasm,81 medium maturity germplasm and 26 late maturity germplasm,and the medium maturity germplasm accounted for 57.4%.Comparing the phenological stages of early,middle and late maturation germplasm,it was found that the length of fruit development period decided the length of the whole growth period.2.The results of field disease resistance evaluation showed that Fusarium wilt mainly occurred in the seedling and seedling stages of muskmelon.Virus diseases mainly occurred at the seedling stage.Powdery mildew occurred after fruiting stage.Vine blight mainly occurs at fruit ripening stage.Thick-skin muskmelon materials2020T29,SL20,SL30,2020T53,SL23,SL74,2020T25,SL3,SL95,2020T03 had better comprehensive resistance,among which SL20 had no disease and had the best disease resistance.3.There were significant differences in soluble sugar content among different germplasm,among which the highest sugar content of 2020T13 was 18.7%,and the lowest sugar content of SL288 was 8.3%.4.According to the analysis of genetic diversity index,the diversity index of quality traits of 15 fruits ranged from 0.274 to 2.041.The diversity index of five quality traits,such as fruit shape,peel background color,fruit surface reticence distribution,flesh color and seed shape,were all greater than 1.0,with great variation.The diversity index of the 14 quantitative traits ranged from 1.761 to 2.068,and the variation coefficient ranged from 9.75% to 47.41%,among which the variation coefficient of yield per plant was the largest,indicating that the quantitative traits were more easily affected by genotype or germplasm than the quality traits.5.Correlation analysis of fruit traits showed that the main factors affecting yield per plant were average fruit weight per plant and number of fruit set per plant;Sugar content was significantly positively correlated with fruit diameter,seed cavity diameter and single fruit weight.The first four principal component factors were extracted by principal component analysis: quality factor,seed cavity factor,fruit shape factor and yield factor,and the cumulative contribution rate reached 78.391%.According to the comprehensive score of principal components,the top five germplasm were SL42,SL29,2020T20,SL90 and SL75.Based on the cluster analysis of 29 fruit traits of 141 muskmelon germplasm resources,seven cultivars were divided into seven groups according to fruit color,fruit shape,single fruit weight and 1000-grain weight,and SL42 and SL29 were divided into one group.Compared with the results of principal components,the second quality group had the best comprehensive fruit performance.6.The comprehensive evaluation results showed that the materials SL3,SL25,SL79,SL4,SL42,SL46,SL2,SL177,SL29,2020T47 had the best performance,which could be used in the germplasm innovation of muskmelon.