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 trees at the Volcani Center in Bet Dagan and in two year old trees at the 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 germination 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 set at live weeks determined. A significant increase was found in the presence of embryo sacs in the ovule, and in the percentage of embryo sacs having a normal egg cell and synergids, with increasing flower age. As a result, there was a consistent and significant increase from anthesis to the third day after anthesis in the percent of flowers having at least one normal ovule. Fruit set of hand pollinated flowers in caged trees exhibited a similar pattern: set was significantly lower in I d old flowers than in 5 d old flowers, where set was highest. The very good set obtained when 5 d old flowers were hand pollinated was probably the result of caging the tree, which significantly lowered the temperature, thereby slowing senescence. These findings clearly show that the 'Mauritius' female flower tends to reach full maturity only 3-5 d after anthesis.