Effect of Harvest Date and Flower Thinning on Flowering and Fruit Growth of Kumquats (Fortunella spp.)
Date Issued
2015
Date
2015
Author(s)
Yeh, You-Chiao
Abstract
In this research, we discussed the possible effects of harvest timing on fruit quality of Fortunella margarita Swingle, Fortunella obovata Tanaka, and Fortunella crassifolia Swingle. We also discussed the effects of flower thinning to flowering time, fruit set timing, and fruit quality of F. margarita Swingle. These allow us to know the possibility of forcing through flower thinning in kumquat production. Kumquat flowers continuesouly during summer, therefore, the time for harvest lasts several months. Whether to harvest or not depends on fruit coloration. According to the criteria for harvest from local cultivators, we harvested fruits from orchards located in Jiaoxi, Ilan, every 15 days starting from Nov. 3rd, 2013. The measurement of total soluble solids and organic acid contents were made to better understand the appropriate time to harvest. Fruits of F. margarita were collected four times from Nov. 3rd to Dec. 18th. The fruits harvested on Dec. 3rd have higher ratio of total soluble solids to organic acid contents, which was 12.37, compared with the rest. The fruits harvested on Nov. 3rd have higher organic acid contents, which was 1.63%. The fruits harvested on Dec. 3rd have higher fruit weights and volume, which were 16.49 g and 17.73 cm3, when comparing to other time of harvest. The appropriate time for harvest starts from December for F. margarita. As for F. obovata, a total of seven times of harvest was done from Nov. 3rd to Feb. 1st next year. The fruits harvested from Nov. 18th to Dec. 18th have an average weight and volume of 37.85 g and 41.63 cm3, which was greater than fruit from other time for harvest. In the fruits harvested on Dec. 3rd, total soluble solid reached 9.24 °Brix, which is the highest in the entire harvest season. The appropriate harvest season for F. obovata is found from Nov. to Dec. As for F. crassifolia, a total of three times of harvest was done from Dec. 3rd to Jan. 2nd next year. The ratio of total soluble solid to organic acid contents decreased from 33.89 to 18.12 if the time for harvest delayed. In short, the appropriate harvest time for premium quality of F. margarita was later than that of F. obovata, with a month of poor fruit quality before the appropriate harvest time, which waste labour cost. If an increment in the number of fruit set can be imposed into the appropriate harvest time, it’s possible to raise grower’s income. From Jun. to Sep., 2014, eight flower thinning treatments were made to thirty-two F. margarita trees in the orchard in Jiaoxi, Ilan. F. margarita flowers four to five times a year, while the time for most flowers anthesis of F. margarita is mainly in first flowering time, an average of seven flowers and two fruits per shoot was observed, which contributed mainly to the total number of fruit set. Flower thinning was done on Jun. 30th, this caused a decrement in total fruit set. However, only flowers were thinned in the first flowering time, the amount of flower anthesis and fruit set in the second flowering time were significantly more than the second flowering time when untreated. If flowers were thinned for three flowering times, the next flowering time and main fruit set timing will be postponed to about two months, with an average number of flowers less than one flower per shoot and lower yield. After thinning, a delay was found in timing of both flowering and fruit set. The later thinning was done, the longer these periods postponed. Although, thinning gave a decrement in total number of fruit set. Relatively low rate of fruit set and drastic yield variation due to weather condition can be assumed, since large amount of flowers anthesis in the first flowering time. In summer, after the first flowering time, the second flowering time appeared for about two weeks later. Flower thinning in the first flowerinng time can asure a delay in the time for the second flowering time with certain amount of flowers and fruit set. In sum, flowering thinning in the 1st flowering time can postpone the time of fruit set for a month, reaching the goal of raising the number of fruit set in the appropriate harvest time for Fortunella margarita Swingle.
Subjects
appropriate harvest time
the ratio of total soluble solid to organic acid contents
fruit set
total soluble solid
organic acid content
Type
thesis
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