2017 ASHS Annual Conference

The United States is the largest producer of blueberries (Vaccinium corymbosum) in the world with a production value of $825 million. Blueberry is an economically important crop that is dependent on pollinators for fruit set. Changes in climate have yielded warmer temperatures which is one of the abiotic factors regulating flower and bee development. The primary role of a flower is to attract pollinators and crop production that requires pollinators has been negatively affected by the decline of honey bees forcing growers to rely on other pollinator species, such as the Japanese hornfaced bee (Osmia cornifrons). The objective of this study was to determine the effect of temperature on flower development and bee emergence. Two cultivars of highbush blueberry ‘Blueray’ and ‘Jersey’ were grown at five temperatures 18, 20, 24, 28, and 31 °C under natural irradiance in a greenhouse. Flower development was investigated by determining the total number of flower clusters, percent bud abortion and flower cluster longevity. The rate of flower development and bee emergence was determined using non-linear regressions. The future temperatures obtained from a climate model were used to generate maps of future synchrony between flowering and emergence using geographic information system (GIS) and R software. Plants grown at 28 °C reached full bloom 13 days earlier than at 18 °C for both cultivars. For ‘Blueray’, increasing temperature promoted flower bud abortion, while temperature did not appear to significantly affect the bud abortion for ‘Jersey’ until plants were exposed to 31 °C. Flower cluster longevity decreased with higher temperatures in ‘Blueray’. The future synchrony maps showed that bees would emerge prior to blueberry flowering. Our data showed flower development was significantly affected by a slight increase in temperature (2 to 4 °C) and cultivar selection. These results suggested that the synchrony between the flowering of blueberry and the emergence of bees could be disrupted by increasing temperature. Therefore, effective management practices designed to synchronize crop flowering and pollinator emergence will be necessary to ensure sustainable crop production in the future.