2018 ASHS Annual Conference

Blueberry is a popular and economically important crop that is primarily pollenated by bees. Crops that require bee pollination must produce a sufficient amount of viable pollen, since bees pack pollen onto their scopae most of the pollen collected is unavailable for pollination. Changes in climate have yielded warmer temperatures impacting flower development including pollen production and the activity of pollinators. Many studies have investigated the viability of pollen exposed to elevated temperatures for short time periods. In other studies pollen was collected under ideal temperatures and then placed under temperature treatments. The objective of this study was to determine the impact of long term exposure to incrementally increasing temperature on the production, release, and viability of pollen from two cultivars of highbush blueberry (Vaccinium corymbosum L.) ‘Blueray’ and ‘Jersey’. Plants were grown at five temperatures 18, 20, 24, 28, and 31 °C under natural irradiance in a greenhouse. Pollen release was evaluated by rolling the flower. Pollen viability was determined by plating pollen on germination media, plated pollen was stored for two hours at the same temperature treatment. Pollen viability, mean number of pollen tubes per germinated tetrad and pollen tube length were evaluated. The longest pollen tube length was observed from plants grown at 18 °C. Few flowers were produced, however, at 31 °C and most of the pollen collected failed to germinate. Our data suggested that long term exposure to even relatively small increases in temperature negatively affected pollen viability. Temperature increase due to climate change could decrease not only activity of pollinators, but also pollen production and viability raising a great concern since it has been liked to poor fruit set, potentially decreasing fruit yield.