Location: Horticultural Crops ResearchTitle: Grow tubes change microclimate and bush architecture but have little effect on bush biomass allocation at the end of the establishment year in blueberry Author
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2014
Publication Date: 5/20/2014
Citation: Tarara, J.M., Chaves, B., Strik, B.C. 2014. Grow tubes change microclimate and bush architecture but have little effect on bush biomass allocation at the end of the establishment year in blueberry. HortScience. 49:596-602. Interpretive Summary: Grow tubes are cylindrical plastic shelters that are placed around young trees and vines to protect them from deer browsing, wind, and chemical applications. There is new interest in using grow tubes to establish blueberry bushes, but there is very little information on how the environment inside the tube affects growth of the blueberry bushes. We put grow tubes around new blueberry plants and measured temperature, light, and humidity in the tubes. The air in the grow tubes was warmer and more humid than the outside air. Light inside the tubes was extremely low. At the end of the bushes' first year in the field, we removed the tubes and measured the growth pattern of the plants. Unexpectedly, the tubes had almost no effect on the growth of stems and roots, but they did affect leaves. Fewer leaves were produced on the 'tubed' plants when they were inside the tubes. More leaves were produced by the 'tubed' plants once the plant tops had grown above the height of the tube. The 'tubed' plants were taller and more upright than the plants grown without tubes. Blueberry growers will have to consider the cost of the tubes, the labor required to install and remove them, and whether a tall, upright young blueberry bush is more desirable than a shorter, more prostrate bush.
Technical Abstract: Microclimate variables were integrated over a six-month period during which blueberry (Vaccinium corymbosum cv. Liberty) bushes were grown in 51-cm high, 20-cm diameter round grow tubes (opaque or translucent) on a sawdust mulch-covered raised bed with the mulch incorporated into tilled soil. Grow tubes were installed around plants in the spring of 2006, five months after planting. Total photosynthetic photon flux density was 55% and 21% of ambient in translucent and opaque tubes, respectively. Daily maximum vapor pressure deficit consistently was highest in translucent tubes. Air (Ta) and stem (Tstem) temperatures in both grow tube types exceeded Ta and Tstem in non-tubed plants (ambient). Maximum mulch surface temperature (Tm) was lowest in opaque tubes whereas there was no difference in Tm between ambient and translucent tubes. The soil-mulch interface temperature (Tsm) was warmer outside tubes compared to Tsm inside tubes. Soil temperatures directly under tubes differed very little between tube types and ambient, generally <1 'C. Root and crown dry mass (DM) did not differ between tubed plants and ambient at the end of the establishment year. Leaf area, leaf DM, and fruit bud number were suppressed inside tubes. All plants were >51 cm tall at the end of the growing season. Substantial compensatory growth occurred above tubes: tubed plants were more upright and had more leaf area, leaf DM, and shoot growth than ambient plants above 51 cm. However, there was no difference between tubed and ambient plants in fruit bud number, total plant leaf area, shoot:root, or DW of one- and two-year old wood. Grow tubes can alter microclimate and architecture of young blueberry bushes but have no significant influence on size and distribution of total DM after one growing season in the field.