Effects of photoperiod and temperature on growth, flowering and fruit yield in annual-fruiting red raspberry cultivars (Rubus idaeus L.).

摘要

Plants of the annual-fruiting raspberry (Rubus idaeus L.) cultivars 'Autumn Treasure', 'Erika' and 'Polka' were raised in a phytotron under different temperature and day-length conditions for six weeks, and subsequently cropped in an open plastic tunnel at latitude 61 degrees N. Flowering and fruit maturation were advanced and yield increased with increasing raising temperature over the 15-25 degrees C range in 'Erika' and 'Polka', while 20 degrees C was optimal for 'Autumn Treasure'. Long day (LD) conditions (20 h) likewise advanced flowering and increased fruit yield compared with 10 h photoperiod at all temperatures in 'Erika' and 'Polka', while photoperiod had no significant effect on flowering and fruit yield in 'Autumn Treasure' . In agreement with earlier findings, low temperature vernalization at 6 degrees Cfor six weeks increased flowering and fruit yield in 'Polka' compared with control plants raised at 18 degrees C. Vernalization also advanced the transition to flowering by reducing the number of nodes formed before flowering in 'Autumn Treasure' without increasing fruit yield, while flowering and fruiting were not promoted by vernalization in 'Erika'. 'Erika' out-yielded the other cultivars under all conditions and produced remarkable yields of 3.3 kg plant-1when raised in LD at 25 degrees C. With its great yield potential and large fruits with excellent flavour, 'Erika' presents itself as a very promising cultivar, especially for environments with long growing season. The number of fruiting nodes was the single most important plant structural component associated with high fruit yield, accounting for 76% of the total variation in the total data material.