Effect of Artificial Media, Temperature Conditions and Storage Methods on in vitro Germination of Dragon Fruit (Hylocereus undatus Britt & Rose) Pollen

摘要

White fresh dragon fruit (synonym: pitaya) (WD) is self-compatible, while the Red fresh dragon fruit (RD) cultivars are incompatible. Therefore, RD cultivars require artificial pollination with pollen from other cultivars to set fruit. The objective of the present study was to identify suitable conditions for pollen germination of WD cultivars as a pollinator, using artificial media at various sugar concentrations and various temperatures. Also various pollen storage methods were evaluated. The use of agar containing 30% sucrose led to the highest values for the percentage of pollen germination and tube elongation. The percentage of pollen germination was reduced at concentrations below 20% and above 40%, and the pollen did not germinate at in the absence of sucrose and at a 50% sucrose concentration. Although the highest germination percentage was observed at 30, 35 and 40°C, the germination percentage decreased at temperatures above 45°C and below 25°C. Pollen germination did not occur at 10 and 55 °C. Pollen germination percentage of fresh pollen and fresh pollen stored for 20 hrs without silica gel exceeded 30%. However, pollen germination did not occur after storage under dry conditions with silica gel at 5"C. Pollen germination and tube elongation were reduced after storage at -20 and -30°C for 15 days. Pollen did not germinate after being stored in acetone and ethyl acetate. Pollen stored in a sucrose solution (from 20% to 60% w/v) remained viable for 3 clays, while pollen germination did not occur after pollen was stored in the absence of sucrose or in 5 and 10% sucrose solutions. It was concluded that the use of sucrose at 30% concentration at 30, 35, and 40°C was suitable for pollen germination and tube elongation, while prevention of exposure of pollen to dry or too wet conditions is necessary for pollen storage of dragon fruit.