SYMBIOTIC NITROGEN FIXATION OF FABA BEAN PLANTS INOCULATED WITH SALT-TOLERANT Rhizobium ISOLATES

Abstract

Rhizobium leguminosarum biovar viciae isolated from salt-affected faba bean fields were in vitro tested. Different isolates were found to be varied in their tolerance to salinity. F1 and E1 were found to be the most salt-tolerant isolates even at EC-level of 12 ds m-1. Seeds of Nubaria 1 cv. were inoculated with either F1 or E1, in comparison with a less salt-tolerant one (F9) in pots their salinity were adjusted at 0, 3, 6, 9 and 12 ds m-1 under aseptic conditions. Number and dry weight of nodules were decreased strongly by increasing salinity levels in comparison with control. Significant enhancement of N % accumulated in the shoots was also noticed due to the biological inoculation with both Rhizobium isolates in presence or absence of salinity. Under non-aseptic conditions, efficacy of F1 and E1 with the effect of mineral N-supply (25 and 100 %) was compared. In addition to Nubaria 1 cv., Sakha 1 cv. was also used in the evaluation process for N-fixation at 0, 6, 9 ds m-1 levels. Number of nodules formed on Nubaria 1 at 9 ds m-1 was highly increased from 7.86 and 5.44 for 25 and 100 % N-supply to 82.33 and 93.33 for F1 and E1, respectively. Accordingly, nodular dry weights were also increased to 0.40 and 0.41 g plant-1 for F1 and E1 instead of 0.13 and 0.08 g plant-1 for 25 and 100 % N, respectively. The beneficial effects of F1 and E1 inoculation were also extended to enhance N % of shoots and seed yield parameters. Therefore, the symbiotic N2-fixation process has a great potential to improve growth and productivity of faba bean plants in comparison with the mineral N-supply to overcome the harmful effects of salinity.

Performance of Rhizobial Inoculants on Yield and Yield Components of Faba Bean in Southern Ethiopia

“…[27] reported that inoculation of the Rhizobium strain with faba bean seeds produced highest nodules. Likewise, the results of [26] and [28] confirmed that inoculation of Rhizobium strains in faba beans significantly increased the number of nodules. Desta et al [23] also reported that inoculation of rhizobia from faba bean significantly increases the number of nodules/plant.…”