Seasonal Fluctuation in Mineral Composition, Ripening and Storage Physiology of ‘King’ Guava (Psidium guajava L. cv ‘King’) Fruits.

• Main Authors: Ming-Hui Wang, 王茗慧
• Other Authors: 林慧玲
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/38278313119024891210

碩士 === 國立中興大學 === 園藝學系所 === 94 === Leaf analysis was used to determine the seasonal changes of mineral elements of‘King’guava. Results showed that the microelement changed very little except for iron, which increased rapidly after September. The macronutrient concentrations remained rather stable during the period of July to September. Likewise the trend was the same for the months of January to March. By contrast, the calcium concentration dropped rapidly from April to August. It is concluded that July to September are the proper time to collect samples for leaf analysis according to the stable condition of the elements in the leaves. The range of variation of mineral elements of‘King’guava in summer and winter are as follows, and can be used as a guide for the diagnosis of mineral disorders in guava: N：1.86-2.11%；P：0.14-0.16%；K：1.18-1.31%；Ca：1.05-1.78%；Mg：0.33-0.34%；Fe：74-106ppm；Mn：63-69ppm；Zn：18-24ppm；Cu：15-29pp for the summer crop. Leaf mineral elements in winter crop (January to March)：N：1.23-1.60%；P：0.17-0.28%；K：1.23-1.60%；Ca：1.25-1.71%；Mg：0.16-0.22%；Fe：139-302ppm；Mn：86-104ppm；Zn：23-33ppm；Cu：18-48ppm. Change in the respiration rate and ethylene production of‘King’guava at different developmental stages was also investigated. The‘King’guava fruit with a 2cm diameter was found to have a relatively high respiration rate on the day of sampling, which dropped gradually, rose again after day 4, and at the same time the fruit showed sign of browning. The respiration rate of middle-sized fruit with a diameter of 5cm to 7cm was relatively low, and the ethylene production rate from‘King’guava was also maintained at very low and steady states. No ethylene production was detected as the developmental stage advanced still further. The‘King’guava with propylene treatment was found to have no capacity of autocatalytic ethylene synthesis. It is likely to be non-climacteric as evidenced by the fruit firmness, total soluble solids and change of peel color of the guava. Effects of low temperature storage on the fruit quality of summer and winter crops stored at 1、5、10℃ were investigated. Samples were taken every week. The fruit firmness decreased with increased time of storing, and was found to be less firm at 5℃. The total soluble solids were higher in the winter fruit than those of the summer fruit. The ascorbic acid was found increased in summer crop while fruits were stored at 1℃ and 5℃. Soluble titratable acidity had no obvious change. No significant change was observed in appearance after the low temperature storage of guava, but browning symptom was found after it was returned to 25℃ for 3 days, especially those stored at 10℃ for 4 weeks. Fruit decay and hypha growth on the skin appeared to be apparent after being stored for 5 week and then returned to room temperature for 3 days. Our results showed that 1℃ seems to be the most suitable temperature for guava storage. The vapor heat treatment was an effective means of controlling the oriental fruit fly in guava fruits. The treatment temperature was 46.5℃ for 15 or 35 minutes but over 40 minutes caused heat injury. Transportation at 1℃ for 7 days could keep the fruit quality. This finding may serve as a reference for transport and quarantine when exporting guava fruits.