Effects of sodium chloride on the hydraulic conductivity of soybean root systems.

Root system hydraulic conductivity (L(P)) was measured on soybean (Glycine max [L.] Merr. var Harosoy) seedlings grown in solution culture and exposed to varying levels of osmotic stress. Hydroponic growth solutions were salinized by additions of NaCl, and the permeability of excised seedling root systems to water was measured. Conductance was estimated at high rates of water flux, where osmotic effects are negligible. L(P) was reduced as the salinity of the growth solution increased. Growth in NaCl for 14 days at -0.17 megapascals and -0.26 megapascals resulted in reductions in L(P) from that of controls by 27% and 72%, respectively. L(P) was correlated with the root/shoot biomass ratio (RS), with larger values of L(P) observed in seedlings with lower RS.