Study On Pericarp Chlorotic Process And Its Relation To Commercial Fruit Shelf Quality And Seed Development In Cucumber

Pericarp color is one of themostimportant appearance qualities of fruit.The commercial fruit of green cucumber is tender when harvested,and their pericarparegradually chloroticafter harvested,which reduces the commodity value and also affects the storage and transportation.In addition,in cucumber breeding and seed production,with the increasing of cucumber maturity,the pericarps appear a certain degree of chilrosis,and the seed collection time is usually determined by both the date of pollination and the color of the pericarp.Under the condition of the same pollination date,the chlorotic degree of different varieties of fruit was different,which affected the judgment of the breeding workers on the time of seed collection.Therefore,this study analyzes that cucumber pericarp chlorotic process and its relation to commercial fruit shelf quality and seed development of cucumber.The main findings are as following:1.The relationship between pericarp pigment and quality ofcommercial cucumber fruits with different chlorotic processes were clarifiedWith the extension of postharvest time,the fruits lost water and wilted with the expanding of fruits head and the shrunking of fruit end in 39-1with rapid chlorosis was more severer than 39-2with slower chlorosis.Within 0-12 days after postharvest,the hardness of the 39-1with rapid chlorosis and 39-2with slower chlorosis varieties decreased by 16.6% and 13.6% respectively,and the weight loss rates increased by 4.9% and 3.7% respectively,and the soluble solids content increased at the beginning and then decreased,and the reduction rate was 17.4.% and 1.9%,and the Vc content of fruits decreased by 29.8% and 24.6% respectively,and nitrite content increased slightly.Comprehensive evaluation of appearance quality and intrinsic quality,39-2with slower chlorosis and 39-1with rapid chlorosis had smaller changes in appearance and less nutrient loss.The content of chlorophyll a,chlorophyll b and total chlorophyll in the cucumber pericarp of two cultivars showed a decreasing trend,and the content of carotenoid increased gradually.The chlorophyll content of 39-2with slower chlorosis was significantly higher than that of 39-1with rapid chlorosis,and the 39-1with rapid chlorosis ratio of carotenoid to chlorophyll was significantly higher than 39-2with slower chlorosis.Within 0-12 days after postharvest,there was a significant negative correlation between chlorophyll content and weight loss rate,and the chlorophyll content had a significant positive correlation with hardness and soluble solids.The ratio of carotenoid to chlorophyll content was significant positively correlated with the weight loss rate,and had a sign ificant negative correlation with hardness,soluble solids,and vitamin C content.2.The relationship betweenthe changes of pigments and seeds in the pericarp of cucumber seedlings with different chlorotic processes was clearly defined.In the mature development process of cucumberfruit,the mature fruit pericarps of six green cucumbers showed different degrees of chlorosis and yellowing,23,39-1,and 23×39-1 had a more rapid chlorotic process and a larger chlorotic degree,and 22-1,39-2,22-1×39-2 had a slow chlorotic process and a small chlorotic degree.Comparison of 23,39-1,23×39-1 with 22-1,39-2,22-1×39-2:the chlorophyll content was lower,and the time of chlorophyll content from rising to declining was earlier,and the rate ofrising in carotenoid content was higher,and the ratio of carotenoiod to chlorophyll content in 25 days after pollination rises higher.With the prolongation of the seed harvesting period,the 1000-grain weight,germination rate,germination potential,germination index,and vigor index of the six green cucumber seeds increased basically.Compared the six green cucumber materials of the same harvesting period,the chlorotic degree of 23,39-1,23×39-1 was greater than 22-1,39-2,22-1×39-2.The germination rate,germination potential,germination index and vigor index of 23,39-1,23×39-1 were significantly higher than those of 22-1,39-2 and 22-1×39-2.The degree of chlorosis and yellowing of pericarp during the harvest period of maturecucumber fruit,that is,the ratio of carotenoids to chlorophyll content in pericarps,was significantly positively correlated with seed germination rate,germination potential,germination index,vigor index,and seedling hypocotyl length.The correlations of seed weight,seedling root,cotyledon length and cotyledon width were not significant.3.The process of chlorosis of cucumber pericarp is influenced by the ratio of carotenoid to chlorophyll content in the pericarp.That is,the change of pigment content in the pericarp represents the chlorotic process of the pericarp.Therefore,the chlorotic process of cucumber pericarp had a certain relationship with the quality of postharvest fruit and the seed development.The degree of chlorotic cucumber pericarp can be used as a reference to judge the postharvest quality change of fruit and the optimum seed-harvest time of fruit.