Storage conditions of soft X-ray irradiated pollen for producing seedless watermelons

Abstract

A safe and efficient method for preserving viable soft X-ray-irradiated pollen for the production of seedless watermelon (Citrullus lanatus L.) from diploid plants was tested by packing the pollen under vacuum, O2, CO2 or N2 gas at 25°C, 4°C or -25°C. Pollen germination rates decreased most rapidly with storage at 25°C and slowest with storage at -25°C. Oxygen as a storage gas was not good for storage of pollen, but pollen stored in N2 or CO2 gave good germination. Pollen stored at -25°C for 90 days germinated, but pollen stored at 4°C for 90 days did not, and N2 storage tended to result in higher fruit set than vacuum storage. Fruit set was significantly affected by pollen storage conditions, with N2 storage being more effective than vacuum storage at 4°C. Storage at -25°C produced little difference in fruit set between vacuum and N2 storage. Thus, temperature was the major factor for maintaining viable and effective pollen, and the use of N2 gas was an effective adjunct. Fruit quality was not significantly affected by storage parameters in this experiment.