Carbon supply and demand in an annual raspberry (Rubus idaeus L.) cropping system

As the interest in raspberry out-of-season production increases, lucrative cropping systems need to be developed. This research studied the feasibility of an annual winter cropping system for raspberry in northern Florida. Bare-root canes of the fall-bearing 'Heritage' and summer-bearing 'Tulameen' were shipped during fall 2001 from northwestern nurseries in the U.S. Canes were planted in a polyethylene tunnel in December at either 25 or 50 cm in-row spacing. Fruit harvest began in March 2002. 'Tulameen' had higher yields per cane due to larger fruit size, better fruit quality and a shorter harvest period than 'Heritage'. Yield per cane decreased while yield per area increased by reducing in-row spacings. However, yield in both cultivars appeared reduced compared with previous work and below the national average of 10 ton/ha. Because root pruning during plant removal from the nursery is necessary for annual cropping systems, further experiments were conducted to determine the importance of root carbohydrates on floricane yield.; Canes of summer-bearing cultivars 'Tulameen' and 'Willamette' were completely girdled (100%), partially girdled (75%), or non-girdled. Partial girdling had no effect on floricane yield components or growth. Complete girdling reduced cane flower number in 'Tulameen' and resulted in cane mortality in 'Willamette'. In 'Tulameen', girdling done at the beginning of bloom decreased fruit number and yield per cane compared with the non-girdled control but had no effect on 'Willamette' yield components. In a separate experiment, girdling 'Tulameen' at the peak of bloom decreased flowering and yield by ∼25% compared with the non-girdled control; however, the differences were not statistically significant. Primocane removal did not affect floricane yield components, but significantly decreased root dry weight.; In the summer-bearing 'Cascade Delight', dormant root pruning significantly reduced flower and fruit number and cane yield. Root pruning did not affect root carbohydrate concentration, but total plant carbohydrate concentration decreased significantly at budbreak.; The annual raspberry cropping system studied in this research shows potential for winter production; however, root pruning decreased cane yield. The decrease in the root carbohydrate pool resulting from root pruning likely had a detrimental effect on late flower differentiation during budbreak and consequently reduced yield.