Earliness and fruit yield and quality of annual-fruiting red raspberry (Rubus idaeus L.): effects of temperature and genotype.

摘要

Earliness, fruit yield and quality of 6 annual-fruiting raspberry cultivars were tested under protected cultivation in a cool Nordic environment. After growing plants for 5 wk in greenhouses with average mean temp. of 20, 22 or 26 degrees C, plants were cropped in an open plastic tunnel at latitude 61 degrees N. Highest yielding cultivars were cv. Autumn Bliss and Polka, with 640 g plant-1. Overall, the most promising cultivar was Polka which combined high yield with large fruits of good flavour and firmness. In earliness, cv. Polka was surpassed only by cv. Autumn Bliss, which confirmed its position as the earliest commercial annual-fruiting cultivar. However, cv. Autumn Bliss had soft fruits with little flavour and a short shelf-life, which greatly reduced the potential of the cultivar for the fresh fruit market. The later ripening cultivar Erika did not complete its crop under these conditions, but its large unrealised yield potential and good fruit quality rendered it extremely promising for environments with a longer growing season. cv. Sugana was late, with low yields and poor fruit quality, while cv. Marcela did not yield enough fruit to be of interest under the present conditions. High temp. during the 5-wk growing generally advanced flowering and fruit ripening in all cultivars, with the notable exception of cv. Autumn Treasure in which flowering was suppressed and strongly delayed by high temp. Under the these conditions there was a highly positive correlation between earliness and fruit yield. Regression analyses identified a low number of dormant buds as the single most important component of plant architecture associated with high fruit yield, accounting for 47% of the total variation.