ISHS Acta Horticulturae 632: XXVI International Horticultural Congress: Citrus and Other Subtropical and Tropical Fruit Crops: Issues, Advances and Opportunities
EFFECT OF GIBBERELLIC ACID, UREA AND KNO3 ON YIELD AND ON COMPOSITION AND NUTRITIONAL QUALITY OF CLEMENTINE MANDARIN FRUIT JUICE |
| Authors: | M. El-Otmani, A. Ait-Oubahou, C.J. Lovatt, F. El-Hassainate, A. Kaanane |
| Keywords: | Citrus reticulata, fruit acidity, aminoacids, vitamin C, juice ammonia content, juice nitrate level, maturity index |
| Abstract:
Clementine mandarin is an alternate-bearing cultivar with fruit of small to medium size, easy peeling, juicy and with an excellent eating quality. It has been reported that preharvest as well as postharvest factors (such as cultural practices and storage conditions) affect yields and composition and quality of citrus fruit. This study reports on research carried out for 2 consecutive years (an “off year” with yield =40 kg/tree and an “on year” with yield =140 kg/tree for untreated control trees) to assess the influence of foliar sprays - of i) urea (containing 46%N) at 1 and 1.6% (w/v) at flower initiation-differentiation to increase flowering, ii) gibberellic acid (GA3, 10 ppm) applied during flowering to increase fruit set and iii) KNO3 (at 5% w/v) applied at ‘June drop’ to increase fruit size - on juice quality of ‘Cadoux’ clementine fruit. Mature trees were used and treatments were applied as foliar sprays to the point of run-off. For the “on year” fruit, juice content of mature fruit was not affected by treatment, nor was the maturity index or NO3- content of the juice. Free aminoacid content was lowest in fruit of untreated trees and in fruit of urea treated trees and greatest in fruit of GA3 and KNO3 treated trees whereas NH4+ content had the opposite trend. Ascorbic acid content was greatest in fruit from trees treated with urea at 1.6%, GA3 and KNO3. In the “off year”, urea increased juice content, reduced acidity and increased the maturity index. In storage, juice acidity decreased and, consequently, the maturity index was increased with the greatest values recorded for the urea treatment. Significance of these results in respect to nutritional value of the fruit is discussed. | |
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