ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
PACLOBUTRAZOL EFFECTS ON MANDARIN UNDER TROPICAL CONDITIONS |
| Authors: | R. Delgado, R. Casamayor, J. L. Rodriguez, P. Cruz, R. Fajardo |
| Abstract:
The control of vegetative growth in citrus has achieved little success so far, despite studies carried out with different synthetic plant growth regulators (Monselise, 1982). Practically, all citrus varieties cropped in Cuba, show a vigorous growth making harvest and other cultural practices increasingly difficult. Paclobutrazol has been reported as a very effective inhibitor in the growth of deciduous fruit trees with positive effects on yields (Williams, 1984). For this study, 'Frost Dancy' (Citrus reticulata Blanco) mandarin trees on Sour orange (Citrus aurantium L) planted in August 1979, spaced at 4 m x 8 m were used. Paclobutrazol was applied in November 1983, in a strip of 30 cm width under the perimeter of the canopy volume. Treatments used were 2,5; 5 and 10 g of active ingredient per tree, dissolved in 5 litres of water. Six replicates of 6 trees per treatment were used. At the end of the growth of each important vegetative flush period, the length, number of leaves and nodes in 40 shoots of 6 trees per treatment were evaluated. The length of internodes was also estimated. Throughout the blooming period, the number of flowers per 0,5 m2 was evaluated weekly in four positions per plant. In the blooming peak, the number of flowers and leaves were evaluated in 300 inflorescences. To study fruit-set, the same inflorescences were used, and the retention of fruits evaluated till June. From May, fruit growth equatorial diameter was measured fortnightly in 20 fruits in 6 plants per treatment. At harvest, 3 samples of 18 fruits per treatment for quality analysis were taken, including weight per fruit, juice percentage, total soluble solids, total acidity and vitamin C content. From January to December 1985, trunk growth, canopy height, diameter, and volume were measured. At harvest, weight of fruits per tree and the weight per canopy volume was estimated. | |
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