Fruit Set Improvement of Highbush Blueberry ( Vaccinium Corymbosum) West of the Cascade Range in the Pacific Northwest: A Review

Abstract

Highbush blueberry is an economically important crop across North America and has become important worldwide. Under certain climatic conditions experienced in various geographical regions, fruit set in blueberry remains relatively poor and contributes to reduced yields. The mechanisms contributing to fruit set are complex. Poor fruit set may be associated with improper or incomplete pollination, inadequate nutrient availability, disease pressure, or poor climatic conditions experienced during critical stages of flowering and fruit set. Improving fruit set in blueberry necessitates the evaluation of floral morphology and the impact of morphology on pollinator efficiency. Pollination requirements as they relate to floral morphology among specific cultivars of blueberry and pollen saturation, as well as the assessment of nutrient applications and their impact on reproductive processes pivotal for fruit set and development, are also in need of further investigation. The objective of this report is to provide a review of the literature addressing pollination and fruit set of highbush blueberry. The development of reproductive buds and flowers are impacted by nutrient availability and associated metabolic compounds and processes. Calcium and boron may be of specific importance for reproductive developmental processes and the requirements, roles, and potential application of these nutrients will be discussed. Variation exists in floral morphology across blueberry cultivars. Additional consideration is given to this variation and how it may impact the efficiency of pollination by primary commercial pollinators. Additionally, the efficacy of pollination may be influenced by pollinator species, the interaction between species of pollinator and cultivar of blueberry, and the environmental conditions during bloom time. These issues are important to understand, especially when considering the development of solutions for the improvement of fruit set for this economically important crop.