Effect of temperature and relative humidity on pollen germination in four strawberry cultivars

Four strawberry cultivars, Florence, Marmolada, Pegasus and Tamella, were used for an investigation to determine the effect of varying relative humidity (RH) and temperature on pollen viability. Pollen was collected from flowers of potted plants grown in a polyethylene tunnel. It was then subjected to four RHs (range 45-85%) and three temperatures (range 10-30 degreesC) for a period of up to 72 hours. Pollen viability was then assessed by recording in vitro germination after 24 hours at 20 degreesC. For all cultivars and treatments, pollen germination decreased with time and the highest germination percentages were always after 6 hours. The greatest reduction in the percentage germination for all cultivars occurred at 30 degreesC and relative humidities of 75-85%. Pollen from Marmolada and Tamella was more resilient than the other cultivars and Marmolada had the greatest longevity at 30 degreesC. For Pegasus and Florence, pollen viability was greatly reduced at the higher temperatures and relative humidities.