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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #188283
Title: Do Primocanes and Floricanes Compete for Soil Water in Blackberry?

Author
item Bryla, David
item STRIK, BERNADINE - OREGON STATE UNIVERSITY

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 10/12/2006
Publication Date: 1/2/2008
Citation: Bryla, D.R., Strik, B.C. 2008. Do primocanes and floricanes compete for soil water in blackberry? Acta Horticulturae. 777:477-482.

Interpretive Summary: Though blackberry is a perennial crop, each cane it produces is biennial. New canes, otherwise known as primocanes, arise from root buds or old stem bases each spring and remain vegetative until floral buds initiate in late summer. The following spring, primocanes become floricanes, which flower and fruit and senesce after harvest. Both primocanes and floricanes exist simultaneously on a single plant and share a single root system. During production, primocanes shade floricane leaves and laterals and potentially compete with them for water and nutrients. The objectives of the present study were to determine the hydraulic relationship between primocanes and floricanes in blackberry and to identify any water limitations to plant and fruit development that might be attributable to within-plant competition among the cane types. On any given day, plant water status was always lower in floricanes than in primocanes throughout the fruiting season, especially during midsummer when crop water demands were high. Lower water status in fruiting floricanes may reduce yield and lower fruit quality. This lower water status also suggests that primocanes and floricanes are hydraulically independent and may therefore compete for water in dry soil conditions. Our next study will identify stategies to increase water status in floricanes and thereby improve blackberry production and quality.

Technical Abstract: A study was done to determine the hydraulic relationship between primocanes and floricanes in ‘Marion’ trailing blackberry and to identify any water limitations to plant and fruit development during alternate-year (biennial) production. Irrigation was applied weekly by drip and scheduled as needed to replace 100% of the estimated crop evapotranspiration (ET) requirements. On any given day, primocane water potential, measured using a pressure chamber, was nearly identical between ‘on-year’ (floricanes and primocanes present) and ‘off-year’ (only primocanes present) plants. Floricane water potential, on the other hand, was consistently lower (by 0.3-0.6 MPa) than primocane water potential throughout the fruiting season, especially during midsummer when crop water demands were high. Water potential was significantly correlated to evaporative water demands (expressed as reference ET) in both cane types, and when normalized to atmospheric conditions, remained nearly constant between irrigations. Such constant water potentials indicate that plant water status was not limited by soil water availability and hence would probably not benefit from extra or more frequent irrigation. However, based on different water potentials between cane types, it appears that primocanes and floricanes are hydraulically independent and therefore may compete for water in dry soil conditions.