Abstract
For the improvement of water-use efficiency in tropical tree seedlings, we evaluated the application of two materials, a super-absorbent polymer (SAP), which increases the water-holding capacity of soil, and a plant growth retardant (PGR), which reduces the foliage size and transpiration rate.
When SAP or PGR was applied, the survival of the tree seedlings was extended. Simultaneous application of both materials enhanced this effect, which was ascribed to the increase of the water retentivity by SAP and the decrease of the transpiration rate associated with leaf area reduction by PGR respectively. In Acacia, the amount of daily water consumption decreased by the application of SAP or PGR, and water-use efficiency was improved. However in some species of trees, for example, in species with broad leaves and a high transpiration rate, such improvement was not always observed.
It is thus important to carry out furthèr studies to determine the application dose of PGR most suitable for the reduction of the transpiration rate and for the rapid recovery of growth retardation after transplanting.
