Studies on the effects of salt tolerant mechanism and water table on growth of halophytes

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We investigated the effects of salt irrigation with 5000ppm saline, 6mm/day (salt irrigated plot) and 3mm/day (dry-salt irrigated plot), and fresh water (control plot) on growth of Poplus alba. Growth and biomass except of root in salt irrigated plots were higher than in the others, especially lowest in dry-salt irrigated plot, but root biomass was not different among treatment plots. This plants under saline irrigation were maintained their lives to control the balance of their above ground biomass to the total one and energy consumption. Amounts of photosynthesis and transpiration for Poplus alba with salt irrigation were decreased, and their diameter growths also were declined, compared with those in fresh water irrigation. As a result water efficiency of this plant was become larger and absorbed salt was sunk in roots, and this mechanism seems to have the salt tolerant strategy for this species. The place of origin for Poplus alba is China and we analyzed physiological characteristics of this species grown under different environments, in Japan (Tottori, Hokkaido) and China (Inner Mongolia). Photosynthesis rate of this species was not different among investigated place, which shows that they keep original genetic adaptabilities in each grown place. Growth of plant on salt accumulated soil was affected by level of water table and its changes. We investigated the effect of water level on high salt tolerant plant (Tamarix chinensis) with salt irrigation of 2000ppm, and there was no growth decrease by salt irrigation, but penetration of their roots to deeper soil layer was prevented around logging water level. Salt contents of the plants in treatments changed water level were higher than those in fixed water level.