CPPU and Ethylene Inhibitors as an Environmentally Friendly Strategy for Improving Fruit Retention, Yield, and Quality in Avocado

Avocado fruit drop after fruit set causes avocado orchards to suffer significant losses in the fruit yield, oil yield, and quality parameters of fruits. An insufficient crop load, as a result of excessive fruit drop, can reduce avocado orchard profitability. Hence, this study aimed to mitigate these problems using 1-methylcyclopropene (1-MCP), aminoethoxyvinylglycine (AVG), and N-(2-Chloro-4-pyridyl)-N′-phenyl urea (CPPU) as an environmentally friendly and cost-effective strategy to reduce accumulative fruit drop and enhance the productivity and quality of Fuerte avocado fruits. The experiment was conducted over two consecutive seasons using a randomized complete block design with eight treatments: control, 1-MCP (200 ppm), AVG (200 ppm), CPPU (5 ppm), 1-MCP + AVG, 1-MCP + CPPU, AVG + CPPU, and 1-MCP + AVG + CPPU. These treatments were applied twice, at full bloom and at the beginning of the fruit set. Avocado trees treated with 5 ppm CPPU significantly reduced accumulative fruit drop. Additionally, treatments with 1-MCP + AVG + CPPU and CPPU at 5 ppm notably improved the yield and quality of Fuerte avocado fruits by increasing fruit weight, length, width, dry matter content, total carbohydrates, crude protein, total soluble solids (TSSs), and fruit mineral content (P, K, Ca, Mg, and Fe). In contrast, treatments with 1-MCP or/and AVG had a negative impact on fruit TSSs, acidity, and carotenoid content, while producing the highest levels of chlorophyll a, b, and total chlorophyll. Treatments with CPPU alone or combined with 1-MCP and/or AVG significantly enhanced avocado oil content, with slight effects on peroxide, iodine, and saponification values. Based on the results, 1-MCP + AVG + CPPU treatment is recommended for avocado growers to enhance fruit growth, yield, quality, and oil production.