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EFFECT OF SALINITY ON RHIZOBIUM SPECIES, NODULATION AND GROWTH OF SOYBEAN (GLYCINE MAX L.)

A. SHEREEN, R.ANSARI, S.S.M. NAQVI AND A.Q. SOOMRO*

Abstract: A pot experiment was conducted to observe the growth, nodulation and ion accumulation of salt tolerant and salt sensitive cultivars of soybean (Glycine max L.) when grown in symbiotic association with rhizobium in the absence of mineral nitrogen at different salinity levels (0.05, 0.1 and 0.2 % NaCl). The rhizobium strains pre-tested for salt tolerance were found more. tolerant than the host plants. Plants were inoculated with a mixture of rhizobial strains at the time of sowing in sterilized sand. Salts showed a greater inhibitory effect on nodulation at 0.1 % NaCI with decreased nodule number and weight than the plant growth. Soybean cultivar ICAL-132 showed better growth and produced more nodules by keeping low sodium in the shoot as compared to sensitive cultivar Loppa which failed to survive at 0.2 % NaCI. Salinity decreased potassium concentration in all cultivars tested, but this reduction was also less in ICAL-132. K:Na ratios showed similar trends. A highly positive correlation was observed between nodules and shoot dry weight.

Atomic Energy Agricultural Research Centre, Tandojam, Pakistan.
Department of Botany, University of Sindh, Jamshoro, Pakistan.