Off-season raspberry production in a sub-tropical climate

During 2002, two raspberry cultivars ('Heritage' and 'Tulameen') were planted inside a polyethylene tunnel during winter at in-row spacings of 50 or 25 cm with 180 cm between rows. Vegetative and floral budbreak began in Feb; however, floral budbreak began earlier for 'Heritage' than for 'Tulameen'. Fruit development period was longer for 'Heritage' (35 days from 50% bloom to 50% harvest) than for 'Tulameen' (30 days). Flowering began at about the same time for both in-row spacings but the bloom period lasted 3-4 days longer for the 50 cm than for the 25 cm spacing. Fruit development period was similar for both plant spacings. There was no interaction between cultivar and spacing on flowering or fruit development period. Ripe fruit were harvested from 9 March through 18 May. There were no differences in flower or fruit numbers between cultivars, averaging 100 fruit per cane. However, fruit size was larger in 'Tulameen' (3.1g) compared with 'Heritage' (1.7g), resulting in increased yields for 'Tulameen'. Fruit number averaged 118 and 80 fruit per cane at the 50 and 25 cm spacing, respectively. There was no effect of spacing on fruit size, but the increased fruit number at the wider spacing resulted in higher individual plant yields compared with the closer spacing. During 2003, 'Tulameen' and 'Willamette' were evaluated under similar conditions using 50 cm in-row spacing. Although our yields compared favorably with raspberry yields in other annual tunnel systems, they were lower than the expected yields from traditional systems, due to decreased fruit number and size.