Pollen Parent Effect on Outcrossing Rate, Yield, and Fruit Characteristics of `Floridian' and `Mauritius' Lychee

Abstract

Fruits produced in two orchards, each consisting of adjacent blocks of `Floridian' and `Mauritius' lychee ( Litchi chinensis Sonn.), were unequivocally identified as selfed or outcrossed by phosphoglucose isomerase (PGP; EC 5.3.1.9) isozyme analysis. The average rate of hybrid production in each orchard was 69% and 87% for `Floridian' and 17% and 65% for `Mauritius', respectively. The percentage of hybrids produced on trees adjacent to those of the other cultivar was invariably significantly higher than that produced on the more distant trees. However a significant correlation between hybrid percentage and proximity to the other cultivar, as well as between hybrid percentage and yield, was found only for `Floridian' in one of the orchards. A significant correlation was found between pollen source and the weights of fruits and seeds in both cultivars. Fruits originating from cross-pollination were heavier and contained heavier seeds than selfed fruits. The most pronounced effect of pollen parent on seed weight was found in `Floridian', which appears to exhibit inbreeding depression.