FOLIAR BORON FERTILIZATION IN ‘HASS’ AVOCADO INCREASES AMINO ACID CONCENTRATIONS AND CELL WALL THICKNESS

Résumé 0

"We studied the effect of foliar applications (0, 0.4, 0.8, 1.2 and 1.6g·l-1) of boron on the concentrations of B, carbohydrates and total soluble amino acids in the leaf and on the thickness of the cell walls of buds in 2.5-year-old avocado cv. Hass trees. Penetration of foliar B application (0.8g·l-1) occurred, but due to the natural fluorescence of the leaf, it was not possible to distinguish the path that the fertilizer followed, nor the time needed for absorption. The increasing levels of B applied in three successive occasions with 20 days intervals did not affect the concentration of this element in leaves, sampled 15 days after the application. There was no effect of B on the concentration of carbohydrates. After the second sampling, there was a positive relationship between the concentration of B applied and the amino acids concentration. Boron increased the cell wall thickness of the buds; 1.2 and 1.6g·l-1 doses increased cell wall thickness in the cortex by 66% and 84% respectively, while in the pith this increase was 71% and 77%, respectively, compared with the control. Based on the enhanced cell wall thickness observed, a concentration of B at 1.2g·l-1 is recommended for foliar application in avocado cv. Hass trees."