Climate Influences Vegetative and Reproductive Components of Primocane-fruiting Red Raspberry Cultivars

Abstract

Climatic elements (solar radiation, daylength, water supply, growing degree days (GDD), corn heat units (CHU), soil, and air temperatures) were monitored to determine which elements could account for the variability in yield of primocane-fruiting red raspberry (Rubus idaeus L.) cultivars. The climatic elements were classed as either having a major or minor influence on the vegetative and reproductive components, based on the frequency of the significance of the multiple regression coefficients. Soil temperature and water supply had a major influence, while daylength, solar radiation, and aboveground temperature (i.e., air, GDD, or CHU) had a lesser influence on these components. Soil temperature had the largest influence during April and May, while water supply was equally influential at all times during the season. Air temperature and solar radiation had their largest influence during the period of flower initiation and development (i.e., June and July), while daylength was most influential from June to October. Berry count, weight, and yield had the highest frequency of associations among the climatic elements, indicating the complexity of the association between these yield components and climate. Total number of nodes/cane, length of the fruiting section/cane, and the harvest period showed the fewest number of associations. Not all cultivars responded similarly to changes in their yield components. `Autumn Bliss' was less sensitive to climatic variation than either `Heritage' or `Redwing'. When `Redwing' was the anomaly, it was usually related to air or soil temperatures.