Mango flowering and production in Réunion alternates: production levels are only high every other year. Another drawback is that production centres on a four-month period, from November to February, with a peak in December that pushes prices down. The aim is to guarantee growers a more consistent income by sustaining production from one year to the next, and also to ensure that mangoes come onto the market, particularly the export market, earlier, by managing harvesting dates more efficiently and ensuring better crop distribution throughout the season.
The researchers first showed that the alternate production pattern was linked to a similar pattern in terms of the trees’ carbon, ie energy, reserves. In a productive year, the many fruits draw sugars from the trees’ carbon reserves, particularly in the fruiting branches but above all in the roots. The following year, the trees have lower carbon reserves, which may account for their poor flowering and resulting lower production. Hence to ensure more consistent mango production from year to year, the team suggests reducing inflorescence and fruit load, to prevent exhaustion of the trees’ carbon reserves.
As regards controlling the flowering date, the team has shown that vegetative growth, flowering and fruiting are closely linked: “Their intensity and evolution over time depend on the characteristics of the growth units [stem section that appears during a given growth period, editor’s note] that are likely to branch, flower or bear fruit”, explains Frédéric Normand. Vegetative growth control techniques, such as pruning or thinning, could thus encourage flowering and modify the flowering date.
These advances mean that it is now possible to test new mango cropping management methods, under a collaborative development project funded by the Ministry of Agriculture and Fisheries**. The project is to be led by CIRAD, and will start in March 2007. The agronomic component of the project is intended to reduce production alternation, control harvesting dates and improve fruit quality. It should also make it possible to test the solutions proposed based on previous results. The new project will also attempt to cut pesticide use by controlling another phenomenon: asynchronized flowering, vegetative growth and fruiting. The idea is to concentrate each of these generally lengthy phases over a shorter period, to ensure that the leaves, flowers and fruits are not exposed to pests and diseases for such a long time. This is crucial for producing better quality fruits in a more ecofriendly way.
BioNews. March 15, 2007.