Prof.Dr Aris Tri Wahyudi Uses Bacteria to Increase the Growth of Soybeans and Corn
Rhizobacteria are root-colonizing bacteria that form symbiotic relationships with many plants. They are often referred to as plant growth-promoting rhizobacteria, or PGPRs. PGPRs increase the availability of nutrients through the solubilization of unavailable forms of nutrients and by the production of siderophores which aids in the facilitating of nutrient transport. Thus, these microbial inoculants can be beneficial for crops, they offer sustainable approach to increase production of crops and health.
This was expressed by one of the Professor of the Faculty of Mathematics and Natural Sciences (FMIPA IPB), Prof. Dr Aris Tri Wahyudi, in a press conference prior his oration in the Executive Lounge of Baranangsiang campus, Bogor, on 26 March 2015. He explained that are numerous species of soil bacteria which flourish in the rhizosphere of plants or around plant tissues including Pseudomonas, Bacillus, Azospirillum, Azotobacter, Acetobacter, and Burkholderia. But only two rizobakteria are important, namely Pseudomonas sp. and Bacillus sp.
Through his research program on rhizobakteria carried out since 2005, Prof. Aris revealed that PGPR enhance plant growth by direct and indirect means. This innovation achieved him to be one the 103 Most Prospective Indonesian Innovation 2011.
"The direct effect is to spur the growth of plants by PGPR through the provision of a variety of growth hormone produced by rhizobakteria and facilitate the retrieval of certain nutrients from the environment. While the indirect effect through PGPR ability to inhibit microbial plant pathogens including fungi such as Fusarium oxysporum, Rhizoctonia solani, and Sclerotium rolfsii, "he said. Mechanisms of biological control by which rhizobacteria can promote plant growth indirectly, i.e., by reducing the level of disease, include antibiosis, induction of systemic resistance, and competition for nutrients and niches.
According to him, more than 80 percent of the rhizobakteria able to inhibit the growth of pathogenic fungi of roots of F. oxysporum, R. solani and S. rolfsii in vitro, respectively. However, it turns out that some isolates of Pseudomonas sp CRB and Bacillus sp CR capable to inhibit more than one type of fungal root pathogens. Rhizobakteria is really potential to be developed and use for the biological control of plant diseasesas and in planta.
In addition, the application inoculants rhizobakteria consortium of soybean in the greenhouse with very higher pH and neutral conditions will increase the growth of soybean plant significantly. Moreover, Rhizobakteria will stimulate not only the growth of the plant, but will also increase the colonization of B. japonicum in the rhizosphere and improve almost doubled the nodulation in soybean (increasing the number of root nodules) by B. japonicum. Biofertilizers are defined as preparations containing living cells or latent cells of efficient strains of microorganisms that help crop plants’ uptake of nutrients by their interactions in the rhizosphere when applied through seed or soil. They accelerate certain microbial processes in the soil which augment the extent of availability of nutrients in a form easily assimilated by plants.
This certainly will determine the growth and production of soybean crops. With regard to the plant diseases control in soybeans caused by fungal pathogens, plant growth promoting rhizobacteria affect the rhizobakteria consortium inoculant of Pseudomonas sp.CRB, Bacillus sp. CR, and B. japonicum BJ11 in neutral conditions (pH at 6.5) were able to fully control 33.8 percent of F. oxysporum, 11.3 percent of S. rolfsii, and 11.1 percent of R. solani. At lower pH conditions (pH at 4.5) rhizobakteria consortium inoculant were initially screened for antifungal activity against 66.7 percent of F. oxysporum, 22.2 percent of S. rolfsii, and 44.5 percent of R. solani. The potential mycopathogen of rhizobakteria consortium inoculant against the disease indicates that they are appropriate biofungicides.
Techniques have been developed for the application of microbial inoculants to the soil as it can enhance the uptake of nutrients by plants and increase the efficiency of mineral fertilizers. Powder form inoculant formula will be capable of being stored at room temperature or at 40 C for 12 months, while form of granule formula can be stored for 6 months.
The best result for the application of powder form fertilizer of rhizobakteria inoculant -Sr M code / NPK0.5 at very lower pH will be 1:54 t/ha, this is an increase of about 25 percent when compared with full NPK fertilizer (1:24 outcome tons / ha). This formula will be capable to suppress the use of NPK fertilizer by 50 percent. The application 50 percent of recommended dose of NPK of powder form inoculant (N-Sr)/NPK0.5) at neutral pH conditions will increase soybean yields about 2.2 t/ha to. When compared with controls (1.9 t/ha), these results has indicated an increase of about 11 percent of soybean production, and able to reduce the use of NPK fertilizer by 50 percent.
The application of Rhizobium-inoculant on neutral land give better effect than that of a full dose of NPK. The indication showed that the application of G formula (M-Sr) /NPK0.5) followed by a half dose of NPK fertilizer it has produced 1.88 t/ha. Formula inoculant rhizobakteria consortium is able to increase soybean production 10 percent and also able to reduce the use of NPK fertilizer by 50 percent. At soils with very low pH or to be acidic levels the exploitation of inoculant formulas as biofertilizer purposes were mixed with chemical fertilizer of NPK could provide excellent yields. The application granular inoculant code G (M-Sr / NPK0.5) recorded highest yield of 1,041 t/ha, thus it has increased 40 percent of production and reduce 50 percent of the use of NPK when compared with plants treated with full dose of NPK fertilizer (yields 0.745 t/ha). The resulting formula shows that it is very effective to increase the soybean production. "PGPR has proved to be effective as bio-inoculant for corn grown under irrigated dryland conditions," he said. (Wied)
