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FRANKIA AND RHIZOBIUM STRAINS AS INOCULUM FOR FAST GROWING TREES IN SALINE ENVIRONMENT

FAUZIA Y. HAFEEZ, SOHAIL HAMEED AND KAUSER A MALIK

Abstract: Frankia strains isolated from actinorhizae of 7 Casuarina/Allocasuarina species were screened for nodulation and nitrogen fixing ability on Casuarina glauco and C. obesa plants under controlled environmental conditions. Five out of 13 strains were found to induce root nodules on C. glauco with none on C. obesa. Similarly various rhizobial strains were screened for nodulation and nitrogen fixation on 4 Acacia species. Frankia strains CcOI and CcI3 and Rhizobium strains Abal, Ar2-1 and PMA63/1 were checked for sodium chloride tolerance in vitro. Frankia strain CcDI showed tolerance for upto 500 mM NaCI concentration (Ec47 dSm^-1 approx.), whereas strain Cc13 was sensitive to even 100 mM NaCI concentration (Ec 9 dSm^-fapprox.). The 3 rhizobial strains showed tolerance upto 300 mM NaCI concentration (Ec 28 dSm^-le approx.). A morphological and dry weight analysis for the initiation and development of sporangia in Frankia strains CcO1 and Cc13 grown on modified basal propionate medium showed increase in dry weight and number of sporangia fonnation.
Indigenous population of rhizobia! cells was found to be very low, 2 cells g^-1 of saline soil with an Ec level. of 5-7 dSm^-l. The Frankia population was completely absent in the saline soil, indicating the require ment for inoculation of the host plants by their respective microorganisms.

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