Effects of non-uniform root zone salinity on water use, Na⁺ recirculation, and Na⁺ and H⁺ flux in cotton

• Published in: Journal of experimental botany Vol. 63; no. 5; pp. 2105 - 2116
• Main Authors: Kong, Xiangqiang, Luo, Zhen, Dong, Hezhong, Eneji, A. Egrinya, Li, Weijiang
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2012
• Subjects: Antiporters; Biological and medical sciences; Biological Transport - physiology; Cotton; Fundamental and applied biological sciences. Psychology; Gossypium - growth & development; Gossypium - metabolism; Gossypium - physiology; Phloem; Phloem - growth & development; Phloem - metabolism; Phloem - physiology; Photosynthesis - physiology; Plant Bark - growth & development; Plant Bark - metabolism; Plant Bark - physiology; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Leaves - physiology; Plant physiology and development; Plant roots; Plant Roots - growth & development; Plant Roots - metabolism; Plant Roots - physiology; Plant Transpiration - physiology; Plants; Plants, Genetically Modified; Potassium - analysis; Potassium - metabolism; RESEARCH PAPER; Research Papers; Salinity; Seedlings - growth & development; Seedlings - metabolism; Seedlings - physiology; Sodium - analysis; Sodium - metabolism; Sodium Chloride - pharmacology; Sodium-Hydrogen Exchangers - metabolism; Soil salinity; Stress, Physiological - physiology; Table salt; Water - physiology; Water consumption; Xylem; Malvaceae; Root; Gossypium; Water use; H; Recirculation; Cotton; Fiber crop; Salinity; Rhizosphere; antiporter; Na; split-root system; Dicotyledones; Angiospermae; Botany; Sodium ion; non-uniform salinity; Spermatophyta
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/err420

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na⁺ concentrations in leaves. The [Na⁺] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na⁺] in the ‘0’ side roots was possibly due to transportation of foliar Na⁺ to roots through phloem. Plants under non-uniform salinity extruded more Na⁺ from the root than those under uniform salinity. Root Na⁺ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na⁺ efflux and H⁺ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na⁺ extrusion was probably due to active Na⁺/H⁺ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na⁺ concentration, transport of excessive foliar Na⁺ to the low salinity side, and enhanced Na⁺ efflux from the low salinity root.