Studies On Storability And Postharvest Biology Of Loquat Fruit Among Cultivars

In this experiment the pericarp morphology and structure, storability and quality of loquat (Eriobotrya japonica Lindl) fruits among five varieties, being the chief cultivars in Fujian Province, were investigated. And then we chosed different kinds of storability of loquat fruits (Eriobotrya japonica Lindl. cv. Jiefangzhong) and (Eriobotrya japonica Lindl. cv. Zaozhong 6) as materials, compared and researched the defference of physio-biochemical changes at 20℃during postharvest ripening of varieties.The results indicated that there were apparent differences in pericarp and cuticle thickness, rusty spot, down and fruit powder of exocarp, cell layer of exocarp and arrangement, pulp texture, stone cell size and distribution, cell layer of endocarp and arrangement among the varieties. It was pointed out that the durable storage characteristics of loquat fruits were thick pericarp and thick cuticle, dense and strong down, a great deal of powder covered the exocarp, more cell layer of exocarp and close arrangement, more rusty spot, thick pulp, parenchyma cell and cell layer arrangement close, big stone-cell which distributed nearby the pulp surface layer, more cell layer of exodermis and close arrangement.Storability differed greatly among ripening fruit of five cultivars stored at 20℃. Fruit of "Jiefangzhong" maintained a best storability, while "Baili" fruit rot easily and showed a worst storability. The results showed that the storability of loquat fruit was related to the contents of loquat fruit water, protopectin, titratable acid and the fruit firmness. The lower the water content, the higher the protopectin and titratable acid contents. Meanwhile, the bigger the fruit firmness, the better the storabitity. The contents of sugar and vitamine C were not directly related to the storability. The total soluble solid, lignin and cellulose mainly influenced the edible quality of loquat. The ratio of sugar to acid and the soluble solids/total acid were the main index that scaled the fruit quality.Fruit physio-biochemical changes at 20℃during postharvest ripening of varieties (cv. Jie Fangzhong and cv. Zaozhong 6) were compared and studied. The results were as follows: the better storability for postharvest "Jie Fangzhong" loquat fruit, the lower rate of losing water, the higher content of titratable acid while titratable acid rapidly dropped, which was regarded as primary respiration substance during early fruit storage. However, the content of total sugar had some raise before falling slowly. During the postharvest ripening of loquat fruit, the activities of phenylalanine ammonia lyase (PAL) went up before falling, the PAL activities and the increscent range of enzyme activities in "Jie Fangzhong" loquat fruit were more greatter. The results showed the changes of PAL activities correlated to the changes of lignin content. Meanwhile, the activities of superoxide dismutase (SOD),catalase (CAT),and peroxidase (POD) also went up before falling, which all had an enzyme activity peak. The variety range of enzyme activities in "Zaozhong 6" loquat fruit was more larger, which showed the metabolism was not stable. Moreover, the enzyme's activity peak of "Zaozhong 6" loquat fruit appeared relatively earlier than "Jie Fangzhong" loquat fruit's. Meanwhile, the content of hydrogen peroxide (H₂O₂) and malondialdenyde (MDA) always maintained higher level for "Zaozhong 6" loquat fruit, suggesting that the lipid peroxidation was more intense than "Jie Fangzhong" loquat fruit's. These characters showed a worse storage effect on the "Zaozhong" 6 loquat fruit.