Relationship of flowering intensity and cropping in fruit species

Abstract

The relationship between intensity of flowering and various aspects of cropping are reviewed for fruit species. Relatively light flowering can limit yield in most fruit species. This commonly occurs in young trees that have not achieved full production and in 'off' years for varieties that display alternate bearing. When trees mature, many species will carry fruit numbers that exceed commercially desired levels, resulting in excessively small fruit and accentuating alternate bearing. The economic disadvantages of excess cropload have resulted in considerable research on fruit thinning and widespread commercial application of this practice. Heavy flowering intensity in some crop species results in economic disadvantages beyond the problems of excessive cropload and resultant small fruit size. Many species flower profusely and have initial fruit set that greatly exceeds tree capacity, resulting in abscission of numerous flowers and fruitlets. Abscised organs can represent a substantial amount of carbohydrates and nutrients, compromising availability of these materials at critical periods in flower and fruit development. The potential implications of this process are best exemplified in 'Naval' orange [Citrus sinensis (L.) Osbeck], where an increase in flowering beyond intermediate intensity results in a reduction in both initial fruit set and final fruit yield at harvest. In several species, there is evidence that fruit size may be reduced by excessive flowering, even when cropload is quickly adjusted to an acceptable level. These data suggest that further research on the advantages of controlling flowering intensity is warranted.