Fruit set and development in seeded and seedless Clementine mandarin

Abstract

A comparative study on fruit set and development of leafy and non-leafy inflorescences of Clementine mandarin ( Citrus reticulata Blanco) cultivars ‘Fino Clementine’ (seedless) and ‘Monreal Clementine’ (seeded) was carried out. Seeded Clementine inflorescences consistently set a higher percentage of fruits than those of seedless Clementine, and leafy inflorescences more than non-leafy ones in both cultivars. The pattern of development of the fruits followed a sigmoid curve, and the beginning of the exponential phase of growth coincided with the beginning of the June drop. ‘Monreal Clementine’ had very low parthenocarpic fruit set capability, since in the absence of self-pollination, only 2% of the fruits attained maturity. Fruit set of ‘Fino Clementine’ could be increased dramatically (about 4 times) by using ‘Sanguino Doble Fino’ orange as the pollinator before anthesis, although the mean number of seeds per fruit was only three. Self-pollination of ‘Fino Clementine’ before anthesis did not significantly increase the percentage of fruit set, although most of the fruits obtained in this case also contained seeds. The increase of fruit set following the use of an appropriate pollinator was associated with a greater early rate of growth of the ovaries, which was preceded by a significant increase in size of the fertilized ovules.