Evaporative and Transpirational Loss from Three Nursery Container Types

There is growing interest in the use of fabric containers for nursery-grown plants. Potential benefits of their use include reductions in circling or girdling roots, maintaining more favorable root zone temperatures and the potential to use recycled or biodegradable materials for the container. While there is little published work comparing evaporative and transpirational loss from plants grown in fabric and black plastic containers, it is believed that plants grown in fabric types have greater water use requirements until established. Our research focused on three container types, all #5 in size: black plastic (BP), Root Pouch® (RP), and Smart Pot® (SP). In a greenhouse study conducted from January to March 2013, we examined evaporative loss from containers containing only substrate. One set of each fabric type was wrapped in plastic to examine if the container sidewall had an effect on evaporative loss. Containers were watered to field capacity and allowed to drain for 24 hours. They were weighed and volumetric water content was measured daily for 26 days.  We found that non-plastic wrapped fabric containers lost water more rapidly than BP and plastic-wrapped fabric containers. A field study was also conducted to examine evaporative and transpirational loss when growing a common shrub in the same three containers.  Bareroot plants were potted in April 2013, grown outdoors, and watered and fertilized until established. Plants were then watered to field capacity and allowed to drain for 24 hours to begin dry down.  Daily weight and volumetric water content measurements were taken until plants reached permanent wilt. In a second field study, plants were watered to field capacity, allowed to drain for 24 hours, and then watered daily at 100% or 75% of ET. Plant growth index (GI) was calculated every three weeks during the study. Leachate was collected to determine plant water use efficiency.