Maternal and Paternal Effects on the Incidence of Double Kernelled Fruits in 'Guara' Almond

Abstract

'Guara' is a self-compatible almond of recent introduction that in a few years has become the most planted cultivar in Spain. However, 'Guara' produces a high percentage of fruits with two seeds. The occurrence of double kernels in almond fruits seriously depreciates the price of nuts as the resulting seed are destined to less profitable uses.In the present work, the effects of pollination treatment, shoot vigor, and the blooming time on the production of double kernelled fruits in 'Guara' were determined. Our results indicated that the paternal genotype did not have a significant effect on pollen tube growth, fertilization rate, fruit set, and double kernel appearance on 'Guara'. No significant effect of shoot vigor was observed, despite differences in flower density and size. Early flowers were more prone to the production of double kernels than late flowers. Early flowers were also significantly heavier. Results suggest a positive effect of the size of the flower on the development of both primary and secondary ovules leading to a higher production of double kernels.