Effects of Post-Flowering Environmental Variation along an Altitudinal Gradient on Chemical Composition of ‘Glen Ample’ Red Raspberry (Rubus idaeus L.)”

The effects of post-flowering environmental conditions on chemical composition of 'Glen Ample' red raspberry were studied by growing plants at three altitudes (128, 340 and 670 m a. s. l.) at the same latitude in central South Norway. Due to day-to-day variation in temperature and precipitation, the average climatic effects over the entire harvest period were evened out and reduced in magnitude, thus complicating the analysis of their effects. However, correlation of fruit chemical composition for the individual weekly harvests with temperature and precipitation data for the current and preceding weeks, revealed significant effects of weather conditions during fruit maturation. At the lower temperature range established in the present experiment, fruit quality attributes such as dry matter, soluble solids, titratable acids, total monomeric anthocyanins, and total phenolic concentration were all positively correlated with increasing temperature during the final two weeks of fruit maturation, while precipitation during the same period had the opposite effect. It is concluded, however, that the negative effect of precipitation was not likely to be a direct plant-water relation effect, but rather an indirect effect related to increased cloudiness and reduced radiation during rainy weather. Specific effects on, and interrelations between individual compounds were observed and discussed.