Investigating the control of fruit drop in mango to support innovative solutions for Australian growers (MG21004)

Early fruit drop remains a major limitation in the commercial production of mangoes. This project aims to improve understanding of the molecular pathways regulating fruit abscission in mango, particularly the relationship between activation of the abscission zone, hormonal changes and carbohydrate reserves leading to early fruit drop. Increased knowledge of changes in molecular signals that occur during early, mid and/or late fruit drop will enable more targeted application of Plant Growth Regulators (PGRs). This project will validate the effect of PGRs on fruit abscission and propose management strategies to minimise early fruit abscission. 
 
During the last six months, the project team has conducted field trials with synthetic auxin, gibberellic acid and synthetic cytokinin, to assess potential effects of these phytohormones on fruit drop. The effect of these PGRs was assessed on final yield, fruit retention and fruit morphology. Samples were collected from the field trials for molecular analysis. The project team conducted bioinformatic analysis of the mango genome and identified sequences for genes potentially involved in phytohormone metabolism and signalling, abscission and sugar signalling. Second season field trials will soon commence across two locations on Calypso, R2E2 and Kensington Pride to improve understanding of phytohormone, gene expression and carbohydrate changes during fruit development and how this is associated with fruit abscission. This includes trials modifying carbohydrate availability.

The research team have recruited a PhD student with experience in tree crop development, reviewed the literature to identify phytohormones with known effects on fruit retention, and conducted field trials with cytokinin, gibberellic acid (GA3) and naphthaleneacetic acid (NAA) application to assess potential effects of these phytohormones on fruit drop.