Rice genotypes differing in salt tolerance II. Short‐term kinetics of NaCl absorption and translocation in intact plants

Abstract

Abstract Two pairs of contrasting rice genotypes, each pair having similar general characteristics but differing in their tolerance to salt, were compared in short‐term experiments of NaCl absorption and translocation in intact plants. At low external NaCl concentration (0.1 mM), the absorption of Na was passive with a constant net influx rate (In), while the absorption of Cl was an active process obeying Michaelis‐Menten kinetics. At both low and high external NaCl concentrations (0.1 and 50 mM), salt‐tolerant ‘Pokkali’ had significantly lower rates of Na and Cl absorption than did salt‐sensitive ‘Peta’, although another moderately salt‐tolerant genotype, ‘IR 29725–25–22–3‐3–3’, did not differ from its salt‐sensitive counterpart, ‘IR 5’. For both pairs of the plants, translocation rates of Na and Cl were significantly lower in the salt‐tolerant genotypes than in the salt‐sensitive ones. It was concluded that exclusion of Na and/or Cl from the shoots may involve both absorption and translocation component...