The 2012 ASHS Annual Conference

Cranberry (Vaccinium macrocarpon Ait.) is a perennial fruit crop native to northeastern continental America.  Terminal buds of cranberry contain a vegetative meristem and, at times, flower initials that are important determinants of next season’s crop.  Biennial bearing is believed to contribute to the reproductive fate of buds, so that uprights fruiting one year will be less likely to set reproductive buds and fruit the following year.  Currently, the industry uses visual assessment of bud external appearance to predict potential yield.  Buds that are perceivably large and round are considered to be reproductive (fruiting), whereas small and narrow buds are considered to be vegetative.  Such methods of yield prediction are widely used among growers and the industry.  Yet, the margin of error between predicted and expected yield is often large.  In order to improve the accuracy of yield prediction, it is necessary to develop a more complete understanding of cranberry bud development.  The objectives of this project are to: 1) characterize bud development and flower initiation throughout an entire growing season; 2) compare development across several cultivars; and 3) determine the relationship between bud external appearance and the presence/absence of flower initials.  One hundred uprights of the cultivars Searles, Stevens, Crimson Queen, and HyRed were collected every two weeks from a marsh located in central Wisconsin.  Sampling extended from March to Dec. 2011 and will continue in 2012.  Uprights were dissected and examined using light and scanning electron microscopy (SEM).  Flower initials were first visible by 29 July.  Preliminary results indicate that many of the assumed vegetative buds contain flower initials, which is counter to conventional knowledge on cranberry bud development.  An exception to this finding was found with the older cultivar, Searles.  These data suggests that recently released cultivars have a greater capacity to form flowers, regardless of the previous or current year’s fruiting status.  Continued monitoring and assessment of bud fate will occur in 2012.  Based on the presented results, current approaches to yield prediction may be in need of reevaluation.  Furthermore, these findings lay the foundation for additional investigations on the physiology of bud development in cranberry.  An enhanced understanding of cranberry bud development is imperative as we seek to improve our understanding of yield.