Low Tunnels Reduce Irrigation Water Needs and Increase Growth, Yield, and Water-use Efficiency in Brussels Sprouts Production

Farmers use low tunnels (LTs) covered with spunbonded fabric to protect warm-season vegetable crops against cold temperatures and extend the growing season. Cool season vegetable crops may also benefit from LTs by enhancing vegetative growth and development. This study investigated the effect of the microenvironmental conditions under LTs on brussels sprouts growth and production as well as water requirements and use efficiency in comparison with those in open fields. Low tunnels increased minimum soil temperature in all trials. By contrast, LTs reduced evapotranspiration (ET) 54% to 68% by reducing solar radiation (SR) and blocking wind in spite of increased maximum air temperatures. Because of reduced ET, water needs and irrigation decreased by 24% to 40%. Furthermore, LTs enhanced vegetative growth (plant leaf area, plant height, and plant dry weight). Sprouts per plant and yield under LTs increased by 29% and 46% in Spring 2017, by 22% and 46% in Fall 2017, and by 29% and 22% in Spring 2018. Considering the increased growth and productivity and reduced irrigation, LTs increased water-use efficiency (WUE) in relation to yield by 62% to 107% in comparison with open fields. Increased total yield and improved WUE illustrate that LTs may be a useful management tool in sustainable production systems in addition to their traditional role for season extension.