Abstract
Pre-anthesis flowers were detached from cherimoya trees and incubated under various temperature/humidity (15–30ºC/40–90% relative humidity [RH]) combinations. The anthesis time was recorded and collected pollen was then subjected to hourly germination tests within 4 h after anthesis. Anthesis time was markedly influenced by temperature, but little by humidity. Flowers reached anthesis earliest (1400–1430 h in the afternoon) at 20ºC and at 25ºC. However, the time period in which anthesis was reached at 25ºC (1400–1500 h) varied more than that at 20ºC. Anthesis occurred 1 h later (1500–1600 h) at 15ºC, and variedly widely from 1400–1700 h at 30ºC. The germination percentage of collected pollen was influenced by pre-anthesis temperatures more than humidity. The germination percentage of the pollen collected just after anthesis was highest (> 90%) when the flower was incubated at 20ºC, and lowest (≈70%) at 30ºC. Germination tended to be low both at high temperature (30ºC) with high humidity (90% RH) and at low temperature (15ºC) with low humidity (40% RH). Pollen-tube elongation just after anthesis was not influenced by temperature or humidity. Thereafter, germination and pollen-tube elongation tended to decrease rapidly at higher temperatures and lower humidities. At high humidity (> 80% RH) at 15–20ºC, the germination percentage was maintained more than 70% for 4 h. Pollen-tube elongation at 3 h after anthesis was highest at 20ºC. The favorable temperature and humidity range was restrictive: around 20ºC with 80–90% RH.
