POLLEN TUBE GROWTH AND DEVELOPMENT OF OVULES IN RELATION TO FRUIT SET IN MANDARINES, CV. 'CLEMENTINE' (CITRUS RETICULATA BLANCO)

S. Eti, R. Stosser
In the mandarine variety 'Clementine', fruit set may be limited despite the fact of abundant flower formation. The flower shows a normal development. The number and quality of pollen grains per flower is comparable with other citrus species and varieties. In the style no special conducting tissue is evident. The pollen tubes are growing intercellularly in the upper part of the style, and reach the ovules by the stylar channels. They enter the ovules through the micropyle. After selfing, pollen tube growth was arrested in the upper third of the style, which indicates the self sterility of this variety. The tubes reached the ovules according to variety after 5 to 12 days.

The differentiation of the ovules shows no abnormalities. At time of anthesis the embryo sacs are differentiated. Shortly after fertilization endosperm development is initiated, whereas division of the zygote occurs only 8 to 10 weeks after anthesis. Flowers shed in the first fall period showed degenerated embryo sacs, indicating lack of pollination.

The reason for the low fruit set is to be seen in the early shedding of most flowers, due to the formation of an abscission layer at the basis of the style, and the poor cross-pollination in monoculture with suitable varieties.

Eti, S. and Stosser, R. (1992). POLLEN TUBE GROWTH AND DEVELOPMENT OF OVULES IN RELATION TO FRUIT SET IN MANDARINES, CV. 'CLEMENTINE' (CITRUS RETICULATA BLANCO). Acta Hortic. 321, 621-625
DOI: 10.17660/ActaHortic.1992.321.74
https://doi.org/10.17660/ActaHortic.1992.321.74

Acta Horticulturae