Effects of salinity on fine root distribution and whole plant biomass of Tamarix ramosissima cuttings

To increase understanding of the influence of soil salinity on fine-root development and whole-plant growth of halophytic species, Tamarix ramosissima cuttings were exposed to various salinity conditions at a constant water table depth. Rooted cuttings of T. ramosissima were individually grown in pots in a greenhouse for 416 days in the following five treatments: 0 (field water only), 50, 100, 200, and 400 mM NaCl. Irrigation water was applied from the bottom of the pots and the water table was kept constant during the experiment. Fine roots were scarce at the surface layer probably because of low moisture and/or high salinity concentrations. Fine-root biomass and length increased in layers with higher soil moisture availability in the control, 50, and 100 mM NaCl treatments. In contrast, the distribution of fine roots appeared to be influenced by salinity in the 200 and 400 mM NaCl treatments. Total biomass and total fine-root length were highest in the 100 mM NaCl treatment, and total biomass was positively correlated with total fine-root length under all conditions, suggesting that variation in fine-root length may have an important effect on the whole-plant biomass of the cuttings across a salinity gradient.