Effect of plant density in long-cane blackberry winter production

Blackberry production in Portugal is increasing mainly in the winter months due to the higher off-season prices. In order to produce fruit in this period growers need to use long-canes. This is a new production system used with great success in raspberries but little is known about its adaptation to the blackberry. Blackberries are plants with a high vegetative growth and nurseries often send to grower plants difficult to manage with primary, secondary and tertiary branches. Two trials of ‘Loch Ness’ blackberry plants grown under protected cultivation were carried out. On the first trial, the effect of cane density per pot (6, 8, 10 and 12 canes) was evaluated; in the second trial, space between pots (0.50, 0.70, 0.85 and 1.00 m with a density of 12 canes per linear meter) was studied. The increase in the number of canes per pot, increased yield, although the weight and solid soluble content of the fruits has decreased. In the second trial the increased competition for space, did not have a direct impact on the yield, except for 1.0 m spacing. The percentage of rejected fruits was lower when spacing increased. Concerning the biometric parameters, both trials were similar with the emergence of fruiting laterals mainly on secondary and tertiary branches, which also had more fruits. According to the results, 12 canes per linear meter with a spacing of 0.85 cm per pots, was the most productive system. However, further studies are needed on cane density at the nurseries since it has a strong effect on long-cane blackberry plant quality and it can change cane density per pot and pot spacing.