Water use by ‘Columbia Star’ trailing blackberry in western Oregon

Authors: CAROLL, JESSE - Missouri State University; Orr, Scott; DAVIS, AMANDA - Oregon State University; STRIK, BERNADINE - Oregon State University; Bryla, David

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2023
Publication Date: 2/2/2024
Citation: Caroll, J.L., Orr, S.T., Davis, A.J., Strik, B.C., Bryla, D.R. 2024. Water use by ‘Columbia Star’ trailing blackberry in western Oregon. Irrigation Science. https://doi.org/10.1007/s00271-023-00912-4.
DOI: https://doi.org/10.1007/s00271-023-00912-4

Interpretive Summary: Irrigation scheduling requires the knowledge of several factors, including rooting depth and the daily water requirements of the crop. ARS researchers in Corvallis, Oregon, used large, underground weighing devices called "lysimeters" to accurately measure daily water use in trailing blackberries, which are grown on roughly 6,200 acres in the United States. At full production, the plants required nearly a half-gallon of water from either rain or irrigation to produce just one blackberry and over 12.5 gallons of water to produce enough berries to fill a 6 oz clamshell. Additional measurements indicated that the plants extracted water primarily from the top two feet of soil on cooler days and up to four feet deep on warmer days. This information will enable growers to make informed decisions on how much water to apply and determine how frequently irrigation is needed to avoid water limitations to crop production in trailing blackberry.

Technical Abstract: Two, large weighing lysimeters were installed near the center of a level, 0.15-ha field and used to measure crop evapotranspiration (ETc) of trailing blackberry (Rubus L. subgenus Rubus Watson ‘Columbia Star’) in western Oregon. The lysimeters were constructed from steel and included an inner soil tank (1.0-m wide x 1.5-m long x 1.5-m deep) positioned within a slightly larger outer tank on four hermetically sealed, shear-beam load cells. Plants were spaced 1.5 x 3.0 m apart (one plant/lysimeter; 2153 plants/ha), irrigated by drip, and trained to a vertical two-wire trellis system. During the first year after planting, when only non-fruiting primocanes were present, ETc totaled 120 mm, or 18% of total potential evapotranspiration (ETo) for the growing season. That year, crop coefficients (Kc), calculated by dividing ETc by ETo obtained from a nearby agricultural weather station, was only 0.24 when the measurements were initiated in early July 2020 and, with exception of a brief decline due to wildfire smoke, steadily increased to 0.81 before leaf fall in early October. The following year, ETc doubled, reaching a total of 275 mm, or 34% of total ETo. At that point, Kc increased from 0.30 at budbreak to 0.48 just before dropping to 0.27 after the plants were scorched during a heat dome event in late June. Yield was lower than expected in year 2 (2.15 kg/plant) due to 39% fruit loss from heat damage. Afterwards, Kc slowly increased with primocane development to its highest value of 0.85 just before leaf fall. By the third year, the plants reached full production (8.46 kg/plant), and ETc had nearly doubled again, reaching a total of 511 mm, or 71% of total ETo. Weekly Kc in year 3 increased from an average of 0.55 in late June to 0.88 in mid-August and stayed relatively constant until the plants were pruned and trained in late September, where it dropped to 0.32. At full production, the plants required an average of 2 L of water from either rain or irrigation to produce each individual fruit and over 48 L of water to produce enough berries to fill a small clamshell (170 g). Soil water content readings indicated the plants extracted water primarily from the top 0.6 m of the soil profile on cooler days and up to 1.2 m deep on warmer days. Each year, ETc and Kc increased primarily with new primocane growth but fluctuated due to unusual weather events (i.e., wildfire smoke, heat dome) and pruning and training during the growing season. Results from the study provide new Kc values for estimating crop water requirements and scheduling irrigation from establishment to full production in trailing blackberry.