Pg. 14-17 Evaluating Maxim for the increase in fruit size and retention in litchi

Many attempts have been made to increase litchi fruit size. Maxim, a synthetic auxin, has shown good results on litchis in many countries including South Africa. Maxim is already registered for citrus in South Africa and registration on litchis is planned.

Maxim was applied at the 1 g, 2 g and 3 g fruitlet stage at two different concentrations and the effect on yield and fruit size determined. All treatments increased yield and fruit size. Economical studies revealed that the application of Maxim can benefit producers to a great extent.

Summary:

• Maxim is a synthetic auxin that has shown promising results in increasing fruit size and retention in litchi and citrus in several countries, including South Africa.
• The study aimed to test the efficacy of Maxim on litchi cv. Mauritius by applying it at different fruitlet growth stages (1 g, 2 g, and 3 g fruit weight) and at two concentrations (20 ppm and 40 ppm).
• The trials were conducted in Nelspruit on 19-year-old litchi trees with treatments including 20 ppm Maxim at 1 g, 2 g, and 3 g stages; 40 ppm Maxim at 3 g stage; and untreated controls.
• Fruit drop was significantly reduced by all Maxim treatments, with the strongest retention effect at 20 ppm applied at 1 g fruit weight and 40 ppm at 3 g stage.
• Fruit size (measured by mass and shoulder width) and yield increased with Maxim treatments, especially the 40 ppm at 3 g stage, which showed the highest fruit mass, size, and yield.
• The 2 g application had positive effects on fruit size and size distribution but was less effective than the 3 g application at higher concentration.
• Fruit size distribution improved with Maxim, showing more fruits in larger size classes favored for export.
• Economic analysis showed that despite the high treatment costs, the increase in yield and fruit size from Maxim applications significantly increased back-to-farm income by up to R31,200 per hectare compared to controls.
• Application timing after the second fruit drop (3 g stage) and higher concentration (40 ppm) were most beneficial for maximizing yield and fruit size.
• The study recommends further trials including other concentrations and timing, and monitoring fruit maturity and shelf-life to optimize Maxim use in litchi production.
• No auxins are currently registered for litchi in South Africa, but registration for Maxim is planned based on these positive results.
• Overall, Maxim application can greatly benefit litchi producers by increasing fruit retention, size, yield, and profitability.