Resumen

ALUJA, Martín et al. Delaying senescence of 'Ruby Red' grapefruit and 'Valencia' oranges by gibberellic acid applications. Rev. Mex. Cienc. Agríc [online]. 2011, vol.2, n.1, pp.41-55. ISSN 2007-0934.

The demonstrate the effectiveness of gibberellic acid (GA₃) in delaying fruit senescence in 'Ruby Red' grapefruit and 'Valencia' oranges under sub-optimal orchard management conditions in tropical Veracruz, Mexico. For grapefruit, one or two applications of three different GA₃ doses (15, 20 and 40 mg L^-1) with or without surfactant (Silwet^® L77) at 0.035, 0.05 or 0.1%, were tested. For oranges, one or two applications of three different GA₃ doses (10, 15 and 20 mg L^-1) with or without surfactant at 0.05%, were tested. Pre-color break application of GA₃, at 10 mg L^-1 and 15 mg L^-1 with surfactant (0.05%), was sufficient to sustain peel firmness and delay colour development in oranges and grapefruit, respectively. GA₃ treatments with surfactant caused increased leaf drop in both citrus cultivars, although this was only noticed in trees treated with the highest surfactant dosages and mainly involved photosynthetically inactive leaves. One application of GA₃ at 15 mg L^-1 with surfactant (0.05%) significantly increased orange and grapefruit weights, resulting in yield increases of ca. 1.7 t ha^-1 for oranges and 1.87 t ha^-1 for grapefruit. A significant decrease in orange drop during the late harvest season in GA₃ treated trees, resulted in a harvest period that could be extended by up to six weeks. The market value of fruit harvested late in the season is up to eight times the value of fruit harvested when the market is saturated.

Palabras llave : Citrus; economic benefit; harvest delay; increase of fruit weight.

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