Impact of salinity on growth and symbiotic properyies of some guar rhizobiza

الملخص EN

The effect of salinity (Ece:0, 4, 8, 12 and 16 dSM-1) on growth of 3 Bradyhizodium strains, an imported strain TAL 169 and two local isolates: ENRRI 16A and ENRRI 16C was studied in the laboratory.

Rhizobial growth was measured in Yeast Extract Mannitol (YEM) broth after incubation at 28C for 5,10,15, and 20 days using a spectrophotometer.

Growth of rhizobia was also estimated by the plate count method after 5 days of incubation.

Two of the Bradyrhizobium strains, TAL 169 and ENRRI 16A, were then used to inoculate guar (Cyamposis tetragonoloba L.) seeds grown in sandy loam soil in pots and irrigated with saline water having different electrical conductivity levels of 0, 2, 4 and dSm-1.

Plant samples were taken 40 days after sowing and number of nodules, dry weight of nodules, shoot dry weight and shoot nitrogen content were determined.

Salinity of 4 dSm-1 significantly reduced growth of the three rhizobia.

However, average number of viable cells/ml tended to be higher in TAL 169 up to EC 8 than in the local strains.

The pot experiment showed that salinity level of 6 dSM-1 significantly reduced nodulation, nodule dry weight and shoot nitrogen content of guar plants.

However, in association with guar, strain ENRRI 16 A was found to be more tolerant to salinity compared with strain TAL 169