Australian study points to hormonal changes in the seed coat as the determining factor in the drop of still immature fruits. The next stage involves developing ways to reduce losses.
Premature drop of avocados still developing is a problem that has affected growers since the 1970s. A five-year research project led by the Australian scientific agency CSIRO and supported by Hort Innovation identified hormonal changes in the seed coat as the factor that triggers this process when carbohydrate availability is reduced. The results were published in the scientific journal Journal of Experimental Botany and help to explain why trees shed a significant portion of fruits before they reach maturity.
According to Harley Smith, the project lead at CSIRO, the research allowed understanding the physiological factors involved in the so-called abscission of immature fruits. The hormonal changes occur in the maternal tissue surrounding the seed and trigger the dropping of the fruits in response to the lower carbohydrate availability. The phenomenon is also influenced by environmental conditions, contributing to annual variations in production and hindering producers’ planning.
The second phase of the project has already identified plant growth regulators with the potential to reduce fruit drop. The aim is to develop tools that can reduce losses and make harvests more stable. The scale of the problem can be substantial: some growers report losses of up to 80% of fruits over a production cycle. John Tyas, executive director of Avocados Australia, regards the results as particularly relevant for the regions of Queensland and Western Australia, where premature drop represents a significant factor reducing productivity.
Australian avocado production exceeds 130,000 tonnes per year and represents around 800 million Australian dollars for the country’s economy. For researchers and growers, understanding the mechanism responsible for the drop is an important step, but the challenge now is to translate this knowledge into effective field solutions. The findings from the growth-regulators research could help reduce losses, although their practical application still needs to be evaluated.
