Improving Off-season Production of Primocane-fruiting Red Raspberry by Altering Summer-pruning Intensity

The effect of pruning intensity on the performance of red raspberry 'Autumn Bliss', 'Autumn Cascade', and 'Heritage' was evaluated as a means of improving the autumn crop under plastic. Primocanes were cut at 0 and 10 nodes (N 0 , N 10 )in the first year of the experiment and at 5 to 25 nodes (N 5 to N 25 )in the second year, in a nonheated plastic greenhouse in southern Portugal. In the first year, cutting the canes at ground level (N 0 ) gave 57 g of fruit per cane for 'Autumn Bliss', 9 g per cane for 'Autumn Cascade', and no fruit for 'Heritage'. Cutting the canes at ten nodes (N 10 ) increased yields and greatly advanced harvest in all three cultivars. In the second year, the best pruning intensities were N 10 for 'Autumn Bliss' with 168 g of fruit per cane, N 20 for 'Autumn Cascade' with 232 g per cane, and N 25 for 'Heritage' with 48 g per cane. In all cultivars, the number of lateral branches per cane increased and their length decreased with longer pruning. Total node number decreased with longer pruning, but the number of fruiting laterals was the same. Only in 'Autumn Bliss' did berry weight significantly decrease with longer pruning. This study clearly shows the possibility of achieving high yields under plastic in October and November with 'Autumn Bliss' and 'Autumn Cascade'. Late cultivars like 'Heritage' must be avoided because of their longer growth cycles.