THE EFFECTS OF DIFFERENT CARRIER MATERIALS ON SOME MORPHOLOGICAL CHARACTERISTICS OF RHIZOBIUM PHASEOLI

Abstract

The study aimed to identify inexpensive and suitable carriers for microbial inoculants as an alternative to chemical fertilizers. The study investigated the effect of different carrier media on rhizobium bacteria's morphological properties. Alternative carrier media to peat were sought to enable longer viability of these bacteria and for more practical and easy agricultural application. Nine different materials (peat, perlite, pumice, mushroom compost, sawdust, barley powder, sludge, coal, K-Humate) and some combined mixtures of these materials (perlite + K-Humate, pumice + K-Humate, and sawdust + K-Humate) were used in the research. Peat was used as the reference carrier material. After the necessary procedures, rhizobium bacteria were inoculated onto the carrier materials and incubated for 6 months at 28±2^oC. After incubation, the rhizobium bacteria were isolated from the carrier media and grown in agar and broth culture media. Some morphological properties of the bacteria were determined on the YMA culture medium. After incubation, K-Humate, coal, barley powder, and sawdust materials were observed to support bacterial growth and were therefore identified as alternative carrier materials to peat in terms of the morphological properties of Rhizobium bacteria. Bacteria isolated from K-Humate showed weak growth at high salt concentrations (4%). All bacteria isolated from the carriers were observed to grow at 30°C and pH values ranging from 3 to 10. Bacteria isolated from sawdust, barley powder, coal, and K-Humate materials exhibited antibiotic resistance. The study demonstrated that K-Humate, coal, barley powder, and sawdust materials can be used as alternative carriers for bacteria instead of peat.