Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2010
Publication Date: 11/1/2010
Citation: Bell, D.J., Stommel, J.R., Rowland, L.J., Drummond, F. 2010. Yield variation among clones of lowbush blueberry as a function of kinship and self-compatibility. Journal of the American Society for Horticultural Science. 135:259-270.
Interpretive Summary: Lowbush blueberry production, which makes up about 1/3 of the total blueberry production in the U.S., is from managed wild fields in Maine. Individual plants of wild lowbush blueberry are quite variable in terms of yield and we are investigating possible causes of these yield differences. Lowbush blueberry is pollinated by rented honey bees which tend to fly short distances, thus plants tend to be pollinated by themselves or by near neighbors. Crosses between individual blueberry plants that are too closely related may result in low yields due to inbreeding. Here we have used molecular markers to examine genetic relatedness of individuals within two wild blueberry fields in Maine, in combination with genetic crosses, to determine if relationship of parents involved in crosses affects yield. We found no evidence of yield being affected by genetic relationship except in the case of self crosses (where the same parent is used as both male and female parent), which generally resulted in lower yields. Importantly, we did find that the better selfers generally yielded more in outcrosses, as well. This information will be useful to other scientists interested in improving yields in lowbush blueberry.
Technical Abstract: Two types of field hand crosses (‘pairwise touching-neighbor’ and a full 5x5 diallel, Griffing’s Model 2, Method 3) were performed, in combination with genetic similarity estimations of mating partners using EST-PCR molecular markers to elucidate genetic factors underlying yield variations among clones (genotypes) of lowbush blueberry (Vaccinium angustifolium Ait.) in two managed fields in Maine. Genetic similarity values for touching pairs ranged from 0.308-0.765. Based upon pairwise touching neighbor crosses, no evidence was found for yield being affected by genetic similarity. However, self-fertility of clones was a significant positive predictor of outcross yields. The calculation of ‘lethal equivalents’, derived from selfing to outcross ratios, showed a large range in genetic load among clones and a higher average load than that previously reported in the related highbush blueberry (V. corymbosum L.). The diallel experiment revealed significant general and specific combining ability for all three post-pollination yield traits measured (proportion fruit set, mean mature seed per pollination, and mean berry weight per pollination). Narrow-sense heritability estimates for all three yield traits were moderately high (h2 = 0.58, 0.46, and 0.56, respectively). It is concluded that phenotypically screening for self-compatible clone yield attributes could be useful in identifying germplasm candidates for breeding and propagation.