Floral structure and phenology of cashew in relation to yield

Abstract

he floral structure and phenology of nine seedling cashew trees were studied for three years in north western Australia. The hermaphrodite and male flowers were similar in structure except that the male flowers lacked a pistil and were smaller than the hermaphrodites. The stigma was covered by a thick cuticle, and the transmitting tissue narrowed toward the base of the style. Flowering occurred after the wet season during the driest and coolest period of the year. The trees produced many more male than hermaphrodite flowers, with the majority of hermaphrodites produced during the first three weeks of the flowering period, two weeks before the peak opening period of the male flowers. There were two peaks of opening per day for both types of flower, one in the early morning and one around midday. Less than 40% of the hermaphrodite flowers set fruit, and this was followed by a high rate of premature fruit shed. There were significant tree to tree differences in the length of the flowering period, the number of hermaphrodite and male flowers, the proportion of hermaphrodite flowers, the number of fruit set, the number of fruit shed, and in the number of mature fruit, but there were no year to year or within—tree differences. In addition, there was a highly significant correlation between the number of hermaphrodite flowers and the numbers of both fruit set and mature fruit. The results suggest that there is scope for selection of superior genotypes, and that the number of hermaphrodite flowers can be used as a reliable and stable selection criterion.