Increasing avocado (Persea americana) yield by applying 1-MCP, an ethylene action inhibitor, during the flowering period and at the early stages of fruitlet development

Avocado, one of the most important tropical fruits, does not reach its full yield potential. Among the main reasons for this deficiency are low fruit set of 0.1–1 %, and massive abscission of young fruitlets. Our aim was to reduce these two phenomena and thereby to increase avocado yield. Our objective was to utilize a practical approach not employed so far in the avocado orchard. We hypothesized that since the phytohormone ethylene is involved in the senescence of the reproductive organs and also in fruit abscission, applying a liquid formula of the ethylene action inhibitor 1-Methylcyclopropene (1-MCP) will improve fertilization, and reduce young fruitlet abscission. The experiments were conducted on the popular cultivar Hass and the relatively heat and drought-tolerant cultivar Gem. Spraying liquid 1-MCP during the flowering period, led to a 50–100 % increase in fruit set followed by a yield rise of up to 50 % in Hass and up to 100 % in Gem. The increase in the number of fruits on the tree did not reduce the average fruit weight. Molecular analysis showed that the increase in fruit set was not accompanied by a rise in self-pollination. Thus, we suggest that the treatment improved pistil receptivity during the female phase but did not extend it until the male phase. Treating young fruitlets with liquid 1-MCP reduced abscission significantly but the effect lessened as the fruit developed, resulting in a moderate increase in yield.