The Relationship between Electrical Conductivity and Growth of Gramineae with Varied Tolerance to Sodic Saline Condition-selectivity of K+, Ca2+, and Mg2+ over Na+ in Puccinellia chinampoensis Ohwi

Abstract

The characteristics of metal macronutrients absorption (K+, Ca2+, Mg2+) over Na+ in the rhizosphere of sodic soils of Puccinellia chinampoensis Ohwi (P. chinampoensis) was investigated and compared with barley and oat. P. chinampoensis is a tolerant plant for sodic conditions. In the experiment, artificial sodic soil with several level of electrical conductivity (EC) values and high pH (pH 10) were made by adding 1mol/L Na2CO3-NaHCO3 buffer (buffer for pH 10) to clay soil mixed with vermiculite. The plants were cultivated in a green house from September to October in 2009 in Iwate University, Morioka, Iwate pref., Japan. Root length, shoot dry weight, and root dry weight of the plants lowered with the increase of soil EC. However, P. chinampoensis showed higher root length and root dry weight as compared with those of the other plants. P. chinampoensis showed the lowest Na level and higher K, Ca, Mg levels in the shoots, which was not affected by the increase of soil EC under high pH condition around 10. Furthermore, P. chinampoensis showed the lowest values of cation level ratios of Na/K, Na/Ca and Na/Mg, and it was not also affected by the increase of soil EC. Therefore, it was suggested that P. chinampoensis had high selectivity of K+, Ca2+ and Mg2+ over Na+ in the rhizosphere of sodic soil. The plant with high root growth ability and high cation selectivity shown in the artificial sodic soils will have a higher ability to survive in the sodic soil. It was shown that P. chinampoensis is well adapted to the sodic conditions. Thus, P. chinampoensis would be useful and make meaningful contributions to recover vegetation of sodic soil.