Effect of Temperature, Relative Humidity and Ethylene on Anther Dehiscence in Aromatic Coconut and Influence of Pollen Germination Media Concentration on Pollen Germination

Abstract

Aromatic coconuts have a low yield from March to May, possibly because anthers do not dehisce during the rainy season, resulting in no pollen release to pollinate the female flowers. This leads to poor pollination and no fruit set in seven months afterward, coinciding with the period of low coconut production. Previous reports indicate that humidity, temperature, and ethylene affect anther dehiscence. However, there have been no reports on aromatic coconut. Therefore, this study investigated the temperature and relative humidity (RH) affecting anther dehiscence in aromatic coconut in a laboratory condition, and the anther dehiscence induced by ethephon. The study found that at a temperature of 40 °C and 60±10% RH, anther dehisced as early as the first hour after the beginning of the experiment and up to 80% by the 11^th hour. At 20 °C and 90±5% RH, anther dehiscence was less than 10% even after 24 hours of testing. Additionally, ethylene at concentrations of 25–75 mL×L^-1 stimulated 50% anther dehiscence by the 14^th hour, while at 100 mL×L^-1, anthers did not dehisce but fell off. Furthermore, when the germination medium was diluted threefold to simulate stigmatic fluid reduced by rain, the pollen germination rate was less than 20%.