CLIMATE INFLUENCES VEGETATIVE AND REPRODUCTIVE COMPONENTS OF PRIMOCANE-FRUITING RED RASPBERRY CULTIVARS

Climatic elements (solar radiation, daylength, water supply, growing d egree days (GDD), corn heat units (CHU), soil, and air temperatures) w ere monitored to determine which elements could account for the variab ility in yield of primocane-fruiting red raspberry (Rubus idaeus L.) c ultivars. The climatic elements were classed as either having a major or minor influence on the vegetative and reproductive components, base d on the frequency of the significance of the multiple regression coef ficients. Soil temperature and water supply had a major influence, whi le daylength, solar radiation, and aboveground temperature (i.e., air, GDD, or CHU) had a lesser influence on these components. Soil tempera ture had the largest influence during April and May, while water suppl y was equally influential at all times during the season. Air temperat ure and solar radiation had their largest influence during the period of flower initiation and development (i.e., June and July), while dayl ength 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 th e fruiting section/cane, and the harvest period showed the fewest numb er of associations. Not all cultivars responded similarly to changes i n their yield components. 'Autumn Bliss' was less sensitive to climati c variation than either 'Heritage' or 'Redwing'. When 'Redwing' was th e anomaly, it was usually related to air or soil temperatures.