Effect of a biostimulant product containing macronutrients and a carboxylic acid (AMEC®) on citrus fruitlet abscission
2012
Gómez-Cadenas, A. | Pérez-Santamarina, R. | Ghorbel, R.
Many fruit trees blossom with high profusion and thereafter exhibit massive fruitlet abscission. In citrus, it has been suggested that after hormonal activation of initial fruit growth, subsequent development is mostly supported by nutrient supply. Thus, competition for photoassimilates is responsible for fruit drop. In this work, the effect of a biostimulant product on citrus fruit abscission was tested. The biostimulant contained N, P, Mg, B and a carboxylic acid (AMEC®) and was sprayed onto Citrus clementine (‘Clemenules’) trees four times every 15 days from flower anthesis. Fruit and leaf drop, leaf nutrient content, gas exchange parameters and hormone contents were measured. The product application decreased fruit abscission during the physiological drop. Treated plants showed a reduction in the substomatal CO(2) concentration which accounts for an increase in the photosynthetic efficiency. Endogenous levels of abscisic and jasmonic acids decreased in leaves of treated plants. No differences between control and treated plants were observed in terms of leaf number, shoot length, hormonal contents in fruitlets, and leaf nutrient content. These data indicate that the beneficial effects of the biostimulant are achieved through the increase in the photosynthetic efficiency that leads to better transport of carbohydrates from leaves to fruitlets. Data exclude any direct effect of the product on fruit abscisic acid levels although a better performance of the plant is suggested by the decrease in the leaf contents of stress-related hormones. The product did not have any effect on the general nutrient status of the plant and did not accelerate the change from reproductive to vegetative growth.
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