STUDIES ON RELATIONSHIP BETWEEN WATER SUPPLY AND TREE GROWTH IN A POPLAR PLANTATION.II.ANALYSIS OF THE RELATIONSHIP BETWEEN WATER SUPPLY IN THE FIELD, WATER-CONSUMPTION FOR TRANSPIRATION AND VOLUME INCREMENT AND ESTIMATION OF WATER REQUIRMENT IN

An irrigation experiment was conducted in an intensively cultivated poplar plantation (Populus deltoides Bartr. cv. "Lux" ex. I-69/55) in 1983-1986. The result of the relationship between water supply, water-consumption for transpiration and volume increment was analysed. The results reveal that with the increase of water supply the water-consumption for transpiration and volume increment raise. The amount of water consumed by the 5-year-old poplar plantation with a spacing of 3×6 m in a growing season is 602.6-879.2 mm. 180.0-215.0 t of water is needed for the increment of each cubic meter volume. The regression between water supply and volume increment was studied. A method for estimation of water requirement and a table of water supply for poplar plantation are recommened.