The Relationship between Nitrogen and Unevenly Degreen Skin of ‘Irwin’ Mango (Mangifera indica L.) Fruits

• Main Authors: Yu-Lin Ni, 倪鈺林
• Other Authors: 謝慶昌
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/49142882209750521672

碩士 === 國立中興大學 === 園藝學系所 === 104 === In the present study, the appearance quality of unevenly colored mangoes after ripening was investigated. This kind of mango did not reach fully de-greened state and show lighter and yellow-green color. The chlorophyll concentration was higher and the anthocyanins concentration was lower in these unevenly de-greened mangoes. There is no significantly difference in respiration rate and ethylene production rate between normal and unevenly de-greened mangoes. The internal quality of mango was further studied, our results indicated that there wasn’t any significantly difference in total soluble solid and firmness between normal and unevenly colored mangoes. Starch and total soluble sugar contents were not correlated. A significantly higher level of nitrogen concentration was noticed in unevenly de-greened mangoes. Suggesting that uneven color in mango fruits may be caused by fertilizing with too much nitrogen. The failure in reaching a fully de-greened state of mango fruits after ripening degraded their appearance quality. The objective of this study is to investigate the effect of excess nitrogen fertilizers on mango fruit color after ripening and the induction of the unevenly de-greened symptom. For each tree, leaves were sprayed with 1000 ppm of urea and another 2000 grams of urea were applied to the roots every two weeks with a total of three applications starting from 60 days after fruit set. Fruits were harvested and fruit quality was evaluated at 90, 120 days after fruit set and fruit quality was also determined in fruits which were harvested at 120 days after fruit set and treated with three days of postharvest ripening. Our results indicated that fruits treated with more nitrogen have higher a-values at the proximal and meddle part, and the distal part is dense yellow-green when harvested at 90 days after fruit set. The appearances of fruits in both control and treatments group are similar, but control fruits have redder color than fruits treated with additional of nitrogen when harvested at 120 days after fruit set. Although there wasn’t significant difference in external appearance of fruits harvested at 120 days after fruit set with three days of ripening. Data showed that fruits treated with additional nitrogen treatment contain significantly higher chlorophyll content and anthocyanins content of the proximal part is 1.5 times less than control fruits. We also observed that nitrogen treatment has lower respiration rate when harvested at 90 days after fruit set, lower ethylene production was observed in fruits harvested at 120 days after fruit set plus three days of postharvest ripening, Fruits harvested at 120 days after fruit set with or without three days of postharvest ripening treatment have significantly higher nitrogen contents in peels and pulps compared to those of control. Fruits with three days of postharvest ripening treatment were significantly harder and heavier than control fruits, in contrast, control fruits have higher soluble solids. Results from this study that indicated excess nitrogen seem to slightly induce the formation of uneven colored fruits in mangoes, and it may affect the rate of fruit ripening and fruit quality.