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Moderate sodium has positive effects on shoots but not roots of salt-tolerant barley grown in a potassium-deficient sandy soil

Ma, Q., Bell, R.ORCID: 0000-0002-7756-3755 and Brennan, R. (2011) Moderate sodium has positive effects on shoots but not roots of salt-tolerant barley grown in a potassium-deficient sandy soil. Crop and Pasture Science, 62 (11). pp. 972-981.

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In the agricultural lands of south-western Australia, salinity severely affects about 1million hectares, and there is also widespread occurrence of potassium (K) deficiency. This study investigated whether the effects of sodium (Na) on crop K nutrition vary with plant salt sensitivity. In a glasshouse experiment with loamy sand, two barley cultivars (Hordeum vulgare L. cv. Gairdner, salt sensitive, and cv. CM72, salt tolerant) and one wheat cultivar (Triticum aestivum L. cv. Wyalkatchem, salt tolerant) were first grown in soil containing 30mg extractableK/kg for 4 weeks to create mildly K-deficient plants, then subjected to Na (as NaCl) and additional K treatments for 3 weeks. Although high Na (300mg Na/kg) reduced leaf numbers, moderate Na (100mg Na/kg) hastened leaf development in barley cultivars but not in wheat. In the salt-tolerant CM72, moderate Na also increased tiller numbers, shoot dry weight and Na accumulation, but not root growth. The positive effect of moderate Na on shoot growth in CM72 was similar to that of adding 45mg K/kg. Root growth relative to shoot growth was enhanced by adequate K supply (75mg K/kg) compared with K deficiency, but not by Na supply. Soil Na greatly reduced the K/Na and Ca/Na ratios in shoots and roots, while additional K supply increased the K/Na ratio with little effect on the Ca/Na ratio. The study showed that the substitution of K by Na in barley and wheat was influenced not only by plant K status, but by the potential for Na uptake in roots and Na accumulation in shoots, which may play a major role in salt tolerance. The increased growth in shoots but not roots of salt-tolerant CM72 in response to moderate Na and the greater adverse effect of soil K deficiency on roots than shoots in all genotypes would make the low-K plants more vulnerable to saline and water-limited environments.

Item Type: Journal Article
Murdoch Affiliation(s): School of Environmental Science
Publisher: CSIRO Publishing
Copyright: © 2011 CSIRO.
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