The effect of foliar application of five plant growth regulators on the growth and yield of lowbush blueberry

The plant growth regulators, daminozide (2500 ppm), chlormequat chloride (1500 ppm), ethephon (500 ppm), mepiquat chloride (100 ppm), and paclobutrazol (1000 ppm), were foliar applied to sprouting-year and to first fruiting-year commercial lowbush blueberry (Vaccinium angustifolium Ait.). In sprouting-year blueberry, flower bud production was increased by paclobutrazol, resulting in significantly improved bloom and yield the following year. In fruiting-year blueberry, flower bud production was significantly increased by paclobutrazol in the year of application and resulted in improved bloom and yield in the following fruiting year. The effects of the other treatments on these parameters were in most cases not significant. Daminozide showed a significant bloom response with a sprouting-year application, but this did not translate into a yield response. Key words: Vaccinium angustifolium, plant growth regulators, paclobutrazol, flower bud production