EFFECTS OF WATER-STRESS ON LEAF GROWTH AND PHOTOSYNTHETIC AND TRANSPIRATION RATES OF TECTONA-GRANDIS

Plants of teak (Tectona grandis L.f.) growing after transplantation to fertile soil for 5-6 months were subjected to water stress by withhol ding watering continuously for 3 weeks. The growth rates of both plant s in height and developing leaves in length were unaffected during the first week after withholding watering, but they were decreased by abo ut 50% during the second week and became negligible during the third w eek of water stress treatment. The rate of leaf production and interno dal elongation were also decreased in plants experienced 2 weeks of wa ter stress. However, after rewatering, these plants regained growth po tential and exhibited high rates of leaf expansion and plant growth co mparable to those of well-watered plants. Diurnal course of net photos ynthetic rate (P-N) of plants subjected to water stress for 2 weeks wa s similar as that of well-watered plants. However, P-N of plants subje cted to water stress for 3 weeks was reduced in the afternoon. Similar ly, stomatal conductance (g(s)) and transpiration rate (E) of plants e xperiencing 3-week water stress were decreased in the afternoon. Soon after rewatering, P-N, g(s) and E reached similar values to those of w ell-watered plants.