Viburnum odoratissimum was chosen as the test material mainly because it can be pruned to form a dense leaf canopy. Each experimental plot measured 6.15x6.15m and contained three baskets, each of which held one plant and its container.
Additional plants were placed around the baskets to create groups with 33, 67 or 100 per cent canopy closure. All plants were watered daily and the baskets were weighed every 30 minutes. Any changes in basket weight were due to water being lost from the plants.
The results showed that individual plants lost less water as the canopy cover increased from 10 to 100 per cent. Removing 60 per cent of the leaves from the bottom of a plant with 100 per cent canopy cover had no effect on water loss.
Evidently, the lower leaves did not lose any water while there was complete canopy cover. Therefore, an isolated plant will lose more water than one in a group. Furthermore, when plants are removed from a group, water can be conserved by moving the remaining plants closer together to fill the gaps completely.
Response of Evapotranspiration of Viburnum Odoratissimum to Canopy Closure and the Implications for Water Conservation During Production and in Landscapes by Beeson (2010). HortScience 45 (3): 359-364. ISHS members can view HortScience from the website www.ishs.org