Effect of environment on citrus fruit abscission and maturation

Abstract

Fruit shedding is an important cause of citrus fruit loss in different citrus producing areas in the world. This physiological process can occur in certain citrus cultivars during the final stage of fruit maturation. The fruit maturation process interacts with the environment and more precisely with climatic factors such as temperature. The maturity parameters that induce fruit drop and the interaction between citrus fruit abscission and climate are not known. To evaluate the effect of environment on fruit maturation and abscission, a multi-site study was carried out in Spain, Tunisia and Corsica on six orange cultivars. The examined parameters were fruit detachment force (FDF), weight, diameter, colour, total soluble sugar (TSS) and titratable acidity (TA). We observed that FDF did not evolve in the same way in the three sites. While in Tunisia and in Spain it decreased, in Corsica, it remained constant throughout the fruit maturation process whatever the orange cultivar. Variation of temperature and radiation measured between the three sites cannot be the direct factors controlling this fruit process. Moreover, FDF seems not to be dependent on the evolution of any fruit quality parameters. Considering these results, fruit abscission and fruit maturation could be two independent phenomena at least under the environmental conditions in Corsica. (Resume d'auteur)