RAPID PROPAGATION OF BLUEBERRY PLANTS USING EX-VITRO ROOTING AND CONTROLLED ACCLIMATIZATION OF MICROPROPAGULES

A protocol is presented that enables a propagator to produce field-sized blueberry transplants within 6 months of obtaining microshoots from tissue culture. The protocol involves subjecting microshoots to ex vitro rooting in a fog chamber under 100 mumol.m-2.s-1 photosynthetic photon flux for 7 weeks, transferring plants to a fog tunnel for 2 weeks, then to a greenhouse for 7 more weeks. Plant survival and rooting of cultivars Berkeley (Vaccinium corymbosum L.) and Northsky (Vaccinium angustifolium xcorymbosum) were near 100% under these conditions. Plantlets in fog chambers receiving 100 mumol.m-2.s-1 grew rapidly, while those at lower irradiance levels grew more slowly, and supplemental CO, enhanced growth only at 50 mumol.m-2.s-1. Growth rates slowed when plants were moved into the fog tunnel; but by the end of 16 weeks, plants that were under high irradiance in the fog chamber had root systems that were 15 to 30 times larger than plants under low irradiance. Within 6 months, these plants were 30 to 60 cm tall and suitable for field planting.