Short-term Effect of Uniconazole on the Water Relations and Growth of Ligustrum

Abstract

Growth of potted Ligustrum was controlled by uniconazole at 3.0 mg a.i./pot. Uniconazole inhibited growth by inducing shorter internodes with smaller diameter and by reducing secondary branching and new leaf production. As a result, the total leaf area of the treated plants was 6396 less than the control plants. The chlorophyll content of recently expanded leaves was 27% lower in treated than in control plants, even though there were no visual differences in leaf color. Leaves of treated plants also had a 28% higher stomatal density than the control. The liquid flow conductance of Ligustrum was 3.7 × 10 -14 m·s -1 ·Pa -1 and was similar for plants in both treatments. Differences in daily water, use between the two treatments began to appear at the same time as differences in growth. Total water use of treated plants was 13% less than that of the control. When daily water use was normalized on a-leaf-area basis, water use between treatments was similar, suggesting that differences in total water use were primarily due to differences in leaf area. For plants in both treatments, peak sap flow rates in the main trunk ranged between 60 and 100 g·h -1 ·m -2 . Leaf conductance, transpiration rates, and water potential were also similar for treated and control plants. Chemical name used: (E)-1-(4-chlorophenyll) -4,4, -dimethyl-2-(l,2,4-triazo1-l-y1)-l-penten-3-ol (uniconazole).