Fruit thinning improves fruit quality and lessen alternate bearing in strawberry guava (Psidium Cattleianum)

Strawberry guava naturally bears a heavy crop at the end of the hot and rainy season, with poor fruit quality as a consequence. Nitrogen triggers a floriferous flush in that species, leading to a better off-season production. Because phenological constraints, nitrogen is usually applied just after the heavy natural crop, and the triggered flush is weak and not very floriferous. As carbohydrate availability seems to play a role in the triggered flush, fruit thinning on the natural production thus appeared to be a means to overcome the low response to nitrogen. Two treatments were compared, thinned and unthinned trees, for their effect on the fruit quality of the natural production, and on the characteristics of the triggered flush. Results showed that fruit thinning had a positive effect on the fruit quality of the natural cycle: the mean fruit weight was improved (7.1 g for thinned trees versus 5.4 g for unthinned trees), but total soluble solids were not affected. Fruit thinning also had a positive effect on the intensity and the floriferous quality of the triggered flush, leading to a heavier off-season crop. The overall annual production was not affected by the treatments and was more evenly distributed between the natural and the triggered production cycles on thinned trees, whereas alternate bearing occurred on unthinned trees. The positive effect of thinning on yield steadiness continued during five consecutive production cycles. (Résumé d'auteur