Uniconizole affects growth and water relations of ligustrum

Growth of ligustrum (Ligustrum japonicum `Texanum') was controlled by the application of the growth regulator, uniconizole, at 3 mg A.I. per 7.6 liter pot. Seventy-nine days after application, growth regulated plants had shorter internodes, smaller stem diameters and reduced secondary branching and new leaf production. Differences in daily water use between the two treatments began to appear at the same time that differences in growth became apparent. Total water use of treated plants was 13% less than the control. When daily water use was normalized on a leaf area basis, water use between treatments was similar, suggesting differences in total water use were primarily due to differences in leaf area. Under well-watered conditions, the sap flow rate in the main trunk of plants in both treatments ranged between 60 and 100 g h-1 m-2 of stem area. Leaf conductance, transpiration rate and water potential were also similar for treated and control plants.