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

研究了5000ppm盐灌、6mm/d（盐灌区）和3mm/d（干盐灌区）以及淡水（对照区）对白杨生长的影响。除根外，盐灌区的生长和生物量均高于其他处理区，干盐灌区最低，但各处理间根系生物量无显著差异。在盐水灌溉下维持植物的生命，以控制其地上生物量与总生物量的平衡和能量消耗。与淡水灌溉相比，盐灌溉降低了白杨的光合作用和蒸腾作用，其直径生长也有所下降。因此，该植物的水分利用效率提高，吸收的盐分沉入根部，这一机制似乎具有该物种的耐盐策略。本研究分析了白杨在日本北海道鸟取县和中国内蒙古不同生长环境下的生理特性。本种的光合速率在不同的研究地没有差异，说明它们在不同的生长地都保持了原有的遗传适应性。盐渍土上植物的生长受地下水位及其变化的影响。研究了高耐盐柽柳（Tamarix chinensis）在2000ppm盐灌条件下，水位对其生长的影响，结果表明：盐灌对柽柳的生长没有影响，但在采伐水位附近，其根系向深层土壤的渗透受到了阻碍。变化水位处理的植株含盐量高于固定水位处理。

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.