Study On Correlation Between Peel Characteristics And Fruit Quality Of Different Cucumber Resources

Cucumber(Cucumis sativus L.)is one of the most important gourd vegetables in Cucurbitaceae,ranking among the top ten vegetables in the world.Due to the influence of internal genetic and external growth environment differences,different cucumber germplasm resources have great differences in appearance traits and quality,among which pericarp traits are particularly important,which directly affect the choice and evaluation of consumers.In recent years,with the improvement of people’s living quality and consumption level,people not only pay attention to the appearance characteristics such as peel color and gloss,but also prefer varieties with rich nutrition and excellent flavor quality when choosing cucumbers for consumption.This study selected 44 from different ecological types of cucumber germplasm resources,and the skin color,papilloma,melon and fruit peel characteristics,such as edges,appearance,texture and nutritional quality of statistics and measurement,analysis of the genetic variability and correlation,and objective evaluation to use cucumber skin features fruit will provide a scientific basis for comprehensive quality,to accelerate the cucumber to the choice of excellent germplasm breeding efficiency.In addition,GC-MS was used to identify and compare the components of aromatic substances in peel and flesh of 6cucumber cultivars,revealing for the first time the aroma differences between peel and flesh of cucumber and the aroma characteristics of different cucumber cultivars.The main research results are as follows:1.Comparison of differences and analysis of coefficient of variation in cucumber peel characteristics and fruit qualityDifferent ecological types of cucumber had great differences in peel characteristics and fruit quality.The peel of North China type cucumber is dark green in color,dense in prickles,deep in edges,and crisp in texture.The peel is thick and hard,and the content of VC in flesh and soluble protein in peel is the highest among the three ecological types.South China type cucumber has rich color,short stalk,hard peel,poor taste,the highest content of Vc in peel and soluble sugar in flesh.European greenhouse type cucumber has thin peel,long stalk,excellent taste quality,and the highest soluble sugar content in peel and soluble protein content in flesh.The coefficients of variation of peel color,hardness and thickness of the three ecological types were all below 50%,indicating weak variation.However,the variation coefficient of the watermelon edge,the size of the cucurbit and the density of the cucurbit of the European greenhouse type cucumber is more than 90%,which is beneficial to the improvement and selective breeding of the European greenhouse type cucumber.2.Correlation analysis of cucumber peel characteristics and fruit quality traitsThere was a significant or extremely significant correlation between cucumber peel characteristics such as prickle,color,thickness and gloss and fruit appearance,taste and nutritional quality.According to the principal component analysis and comprehensive evaluation,the cucumber varieties with the appearance characteristics of thin peel,good luster,shallow edge,small bump,short handle and short stalk had better taste and nutritional quality.3.Identification and comparison of aromatic substances in peel and flesh of cucumberBy identifying and comparing the components of aromatic substances in the peel and flesh of 6 different cucumber cultivars,it was found that the aromatic substances in the peel and flesh of cucumber cultivars were rich and different to some degree.There were 60 and47 kinds of aromatic in the peel and flesh of cucumber cultivars respectively,mainly including aldehydes,alcohols,ketones,esters and hydrocarbons.Aldehydes were the main flavor compounds in cucumber flesh,and its content was 83.78%～96.31% of the total flavor compounds,which was significantly higher than that in cucumber peel.While other aromatic substances such as alcohols,ketones,and esters were mainly distributed in the flesh.By comprehensive comparison of the characteristic aroma compounds in the peel and flesh of cucumber,it suggested that the cucumber flavor of cucumber fruits mainly comes from the flesh,while the fresh fragrance comes from the peel.There were significant differences in aroma and flavor among the six cucumber varieties.European greenhouse cucumber ‘Nanshui No.2’,‘Nanshui No.8’ and ‘Biyu’ cucumber had unique sweet fruit flavor,and ‘Nanshui No.8’ cucumber had the strongest aroma and flavor.