Blueberry hybrids with complex genetic backgrounds evaluated on mineral soils: Stature, growth rate, yield potential and adaptability to mineral soilconditions as influenced by parental species

A population of 54 blueberry (Vaccinium subsection Cyanococcus) cultivars o r interspecific hybrid selections derived from combinations of nine Vaccini um species were evaluated in replicated trial for their mineral soil adapta tion response. Individuals within the population varied significantly for t he following objectively-measured traits: plant form (height and volume), g rowth pattern and rate (canopy volume increase over time) and fruit yield/v olume. Subjective evaluations also uncovered a high level of variability am ong genotypes for vegetative vigor (the ability to produce new shoots in pr oportion to existing plant mass), fruit/foliage ratio (the ability to balan ce fruit production and vegetative/floral growth/induction) and freedom fro m foliar nutrient deficiency symptoms. Indices based on subjective evaluati ons and compared to objective measurements indicated the following genotype s to exhibit a moderate degree of mineral soil adaptation: 'Jersey: 'Sunris e; US 612, 645, 665, 673, 676, 693, 702, 714, 723, 730, 845 and 848. When g enotypes were grouped according to their genetic constitutions, significant heritage effects were found for plant height, fruit yield/volume, 1995 and 1996 vegetative vigor scores and 1995 fruit/foliage ratios. However substa ntial within group variability for all traits was evident, suggesting that mineral soil adaptation can be derived from a number of species combination s. Although some deleterious patterns in growth and yield potential can be anticipated when interspecific hybridization is used within a blueberry bre eding program, unique individuals do appear which have captured beneficial traits (such as mineral soil adaptation) from feral species.