Leaf Concentrations Of Na Research Articles

EFFECTS OF VESICULAR–ARBUSCULAR MYCORRHIZAE ON DISTICHLIS SPICATA UNDER THREE SALINITY LEVELS

SUMMARYInland and coastal populations of the salt‐tolerant plant Distichlis spicata were grown under three salinity levels (0, 1000 and 2000 mg Na+ added kg−1 soil as NaCl) with and without inoculum of vesicular–arbuscular mycorrhizae. Mycorrhizal infection averaged 28% for the inland plants and 9% for the coastal plants, and was unaffected by soil salinity. Dry mass of non‐mycorrhizal plants was significantly higher at the low salinity for inland plants and at the intermediate salinity for coastal plants. Mycorrhizal roots had higher Na concentrations than did non‐mycorrhizal roots, but also had higher K and P concentrations, and thus maintained a high K/Na ratio. Leaf concentrations of Na were similar in mycorrhizal and non‐mycorrhizal plants. Excretion by salt glands may serve to maintain constant leaf Na concentrations. Stomatal conductances were the same for mycorrhizal and non‐mycorrhizal plants at all salinities. While mycorrhizae had little effect on D. spicata in this short‐term greenhouse experiment, a full evaluation might require long‐term field observations.

The Influence of Potassium on the Transpiration Rate and Stomatal Opening in Triticum aestivum andPisum sativum

AbstractThe investigation concerns the influence of potassium on the transpiration rate of Triticum aestivum and Pisum sativum grown in nutrient solutions. Plants with high amounts of potassium were found to have the lowest transpiration rates. Shoot/root ratio, stomatal frequency, and stomatal aperture were correlated with the potassium concentration in the leaves. In Triticum no correlations with leaf concentration of Na were evident.Short term experiments were carried out in order to investigate the effects on the transpiration rate of a sudden increase in potassium concentration in the nutrient solution. An addition of potassium chloride to potassium deficient wheat plants resulted in a decrease in the transpiration rate of up to 50% within two hours. Comparative tests with sodium chloride resulted in a decrease in transpiration rate of the same magnitude, indicating that the short‐time reaction is not specific to potassium.The experiments show that the transpiration rate can be regulated by varied potassium and sodium concentrations. The observed effect is supposed to be due to changes in the stomatal aperture.