Exploration of Non-Symbiotic Nitrogen-Fixing Bacteria from Green Bean Rhizosphere (Vigna radiate L.) from Three Locations.

Abstract

Nitrogen (N) is the most abundant element in the atmosphere. However N is the nutrient that is most often deficient in agricultural soils. This contradiction due to N is the largest amount of nutrients needed in plant growth. The function of N nutrients is very important especially in the formation of protein compounds in plants. This study aims were to screen and isolate non-symbiotic nitrogen-fixing bacteria, also to determine the bacterial population from the three regions. Then, results of screening and isolation were checked the antagonism, observed its potential as a consortium bacteria,  tested total ammonia production and the possibility of pathogenicity. This research was an exploratory study carried out from April to July 2016. The locations of sampling were in three locations in Malang, East Java, namely Kendalpayak Experimental Garden, Jambegede Experimental Garden and Junrejo Forest. Determination of the location was based on the continuous fertilization and planting activities compared to the forest. Soil sampling was carried out around the roots of green beans, because in this zone has a high soil fertility level due to high microbial activity. The research stages included screening, isolation and characterization. We selected 4 isolates, namely SNF4, SNF5, SNF7 and SNF8. Antagonistic tests showed that there were no inhibitory zones with each other and the pathogenicity test did not show pathogenic properties of green bean germination. The design used was a Completely Randomized Design consisting of 4 treatments and 1 control. Nitrogen fixing bacterial isolates had have a significant effect on green bean germination. The possibility of this type of bacteria is producing plant hormones. From the N-fixing bacterial exploration activities, there were differences in the number of populations in each soil sample. The four bacteria were not antagonistic and pathogenic. From the results of testing ammonia production was able to do N-fixation with a high ability. Based on the antagonism test shows that four bacteria are potential as consortium bacteria because they did not cause disease in mung bean plants (not pathogens) and did not affect or inhibit the growth of mung bean plants.