Relationship between alternate bearing and apical bud development in cranberry (Vaccinium macrocarpon)

Authors: BOLIVAR, JENNY - University Of Wisconsin; Zalapa, Juan; ATUCHA, AMAYA - University Of Wisconsin; PATERSON, SARA - University Of Wisconsin

Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2018
Publication Date: 11/13/2018
Citation: Bolivar, J., Zalapa, J.E., Atucha, A., Paterson, S. 2018. Relationship between alternate bearing and apical bud development in cranberry (Vaccinium macrocarpon). American Journal of Botany. 97(2):101-111. https://doi.org/10.1139/cjb-2018-0058.
DOI: https://doi.org/10.1139/cjb-2018-0058

Interpretive Summary: Similar to other woody crops, cranberry exhibits alternating years with high and low yields; however, this phenomenon is not well understood. The potential of flowers to form each year is one of the factors that regulates the alternate yield tendency. Unfortunately, little is known about the differentiation of floral organs in cranberry, especially plants that present a lower tendency to alternate yield This study evaluates early flower development in vegetative and flowering branches of alternate and non-alternate yielding plants. Vegetative and flowering branches were collected weekly throughout the growing season to evaluate flower initiation in both types of branches. The results of our study show that differentiation of flower initials starts earlier on the growing season in the non-alternate bearing plants. A strong association was found between the size of buds and the presence of flower initials. In addition, branches from the alternate yielding plants exhibited differences in the growth rates between vegetative and reproductive buds. This study is useful for growers, researchers, and breeders to horticulturally manage alternate and non-alternate yielding plants and to predict yield based on bud size as a predictor of flowering and subsequently fruit set.

Technical Abstract: Similar to other woody crops, cranberry exhibits alternate years bearing; however, this trait is not well understood. The potential of uprights to differentiate floral initials for the following year is one of the factors that regulates the alternate bearing tendency. Unfortunately, little is known about the differentiation of floral initials in cranberry, especially in genotypes that present a lower tendency to alternate bearing. This study evaluates bud morphology and the presence of floral initials through characterization of longitudinal sections of apical buds from vegetative and fruiting uprights of an alternate and non-alternate bearing genotypes. Apices of vegetative and fruiting uprights were collected weekly throughout the growing season and prepared to evaluate the morphology of tissue structures associated with floral initiation in both vegetative and fruiting uprights. The results of our study show that differentiation of floral initials starts earlier on the growing season in the non-alternate bearing genotype. A strong correlation was found between the size of terminal buds and the presence of flower primordia, with increased bud widths associated with the presence of floral initials. In addition, uprights from the alternate bearing genotype exhibited significant differences in the growth rates between vegetative and reproductive buds.