Submitted to: New Jersey Annual Vegetable Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/13/2009
Publication Date: 1/15/2009
Citation: Ehlenfeldt, M.K. 2009. Yield, berry weight, and seed set observations in Duke and Bluecrop highbush blueberries. New Jersey Annual Vegetable Meeting Proceedings. 94.
Interpretive Summary: To answer grower questions of whether small berry size was equated with poor pollination and reduced yield, we monitored yields and berry weights of two standard highbush blueberry cultivars, Duke and Bluecrop, for at least 3 harvests each season over nine years, and evaluated seed set at each harvest over the last four. Across 9 years, yield and berry weight had no significant correlation. For the four years in which seed counts were made, we found that, in general, berry weight and number of seeds/berry decreased linearly between first and third harvests. Exceptions to this apparently reflected varying pollination conditions during the bloom period. More importantly, berries with similar seed numbers varied in weight as much as 86% between years, hence, reduced berry weight was not necessarily due to poor pollination. Possible 3-year yield cycles were observed in NJ, with peak years typically followed by 2 years of declining yield. These results will be of value to growers interested in optimizing blueberry yields and fruit size.
Technical Abstract: Yield is influenced by many factors, but relatively few studies have tried to dissect the components of yield. This talk is part of ongoing studies evaluating yield interactions in blueberry. It discusses concepts regarding berry weight and seed set (pollination) that contribute to yield. Among our pertinent observations have been: 1) across a 10 year period, in our experimental plots, no correlation whatsoever was observed between berry weight and yield; 2) berry weight is reflective of pollination, but only to a degree. Within a given year higher numbers of seed stimulate bigger fruit size, but across years, berries with similar seed numbers (e.g. having equivalent pollination) varied in weight as much as 86%; 3) berry weight decreased very consistently from 1st harvest to final harvest for ‘Bluecrop’, but for ‘Duke’ these patterns were inconsistent; and 4) possible 3-year yield cycles were observed in N.J., with peak years typically followed by 2 years of declining yield. The reasons for these putative cycles are, at this point, unknown and may represent environmental effects, cultural practices, or some combination of the two.