FEMALE MAURITIUS LITCHI FLOWERS ARE NOT FULLY MATURE AT ANTHESIS

Maturity, morphology, receptivity and senescence of female 'Mauritius' litchi (Litchi chinensis Sonn.) flowers were studied in 12 year old t rees at the Volcani Center in Bet Dagan and in two year old trees at t he Faculty of Agriculture phytotron in Rehovot. The stigmatic papillae and receptivity, as determined by pollen germination and pollen-tube growth, began to deteriorate and decrease, respectively, on the third day after anthesis. Six day-old papillae had collapsed and no pollen g ermination occurred. During early, mid and late blooming periods, 1, 3 and 5 d old flowers were sampled for anatomical study. The following year, similar flowers were hand-pollinated on caged trees and their se t at five weeks determined. A significant increase was found in the pr esence of embryo sacs in the ovule, and in the percentage of embryo sa cs having a normal egg cell and synergids; with increasing flower age. As a result, there was a consistent and significant increase from ant hesis to the third day after anthesis in the percent of flowers having at least one normal ovule. Fruit set of hand pollinated flowers in ca ged trees exhibited a similar pattern: set was significantly lower in 1 d old flowers than in 5 d old flowers, where set was highest. The ve ry good set obtained when 5 d old flowers were hand pollinated was pro bably the result of caging the tree, which significantly lowered the t emperature, thereby slowing senescence. These findings clearly show th at the 'Mauritius' female flower tends to reach full maturity only 3-5 d after anthesis.