Abstract

Unfruitfulness is a major problem in many fruit crops and their varieties result in huge loss to growers and make fruit cultivation less profitable. Unfruitfulness in fruit crops refers to the state where the plant is not capable of flowering and bearing fruit. However, the causes of unfruitfulness can be broadly grouped into two categories: Internal and external factors. Among the internal factors, dichogamy prevents self pollination in perfect as well as monoecious flowers. The occurrence of flowers with variable style length (heterostyly) is common in Prunus fruits. The proportion of aborted pollen grains varied from 22.5 to 48.0% in cashewnut. In apricot cv. ‘Trevatt Blue’, multiple ovules and anthers with degenerated microspores resulted in both female and male sterility and in ‘Tokaloglu’, the reason for unfruitfulness is self incompatibility (Gulcan and Askin, 1991). External factors, like temperature that is above 32°C, result in desiccation of stigmatic surface and more rapid deterioration of embryo sac occurrence. For high productivity in delicious apple plant diploid, self-fruitful and compatible varieties ensure cross pollination. Sequential introduction of honeybee increases fruit set and yield of ‘Spadona’ pear by about 50 to 80%. Foliar application of boron at a concentration of 200 mgl-1 increases pollen germination rate and tube growth in pear.

Key words: Unfruitfulness, fruit crops, internal factors, external factors.