EFFICACY OF RHIZOSPHERIC ORGANISM Rhizobium leguminosarum AGAINST Meloidogyne incognita IN SOYBEAN

Abstract

Present investigation was carried out to assess the biocontrol potential of Rhizobium leguminosarum against root-knot nematode, Meloidogyne incognita on soybean. Effect of Rhizobium strains LSI-21 and CRI-29 was assessed individually and concomitantly on reproduction of M. incognita. In vitro studies were conducted to check the effect of Rhizobium strains on egg hatching and juvenile mortality of M. incognita. Concomitant application of Rhizobium strains was more effective in reducing egg hatching and causing juvenile mortality as compared to individual treatment. In green house, Rhizobium strains were used as soil drench and seed dressing for the management of root knot nematode on soybean. It caused considerable reduction in reproduction of root knot nematode as well as improved plant growth parameters of soybean. Seed dressing showed most significant results than soil drenching. It is interesting to note that Rhizobia not only controlled reproduction of M. incognita but also an increase in plant height, fresh and dry root shoot weight was observed. It would seem that Rhizobium being a good rhizosphere organism for field and vegetable crops presumably prevent the contact of pathogenic organisms on roots.

Isolation and Diagnosis of the Root Nodule Bacteria Associated with Mung Bean Plant in Gypsiferous Soil and Testing the Promotional Criterion of Isolates

“…All isolates gave a positive result for the catalase test, indicating their ability to break down hydrogen peroxide, leading to the release of oxygen bubbles, which is consistent with [28], in their study on Rhizobium bacteria isolated from the roots of nine legume plant species. Most isolates also gave a positive result for the oxidase test, which is consistent with , [29] in their study on Rhizobium leguminosarum bacteria in soybean plants. Most isolates gave a negative result for the indole test, which is consistent with, [30] in their Identification of B.japonicum bacteria isolated from soybean and cowpea plants.…”

Seed Coating: A Tool for Delivering Beneficial Microbes to Agricultural Crops

“…Published data of comparisons between the efficiency and feasibility of inoculation of PBM via seed coating and other methods are still scarce. In a greenhouse experiment, after comparing seed coating of Rhizobium strains with soil drench application for the management of root-knot nematode Meloidogyne incognita on soybean, Ahmed et al (2016a) found that seed dressing was more effective in controlling the reproduction of M. incognita and increasing plant height, and fresh and dry root and shoot weight. In a trial using maize, Rocha et al (2019a) compared the delivery efficiency of R. irregularis via soil inoculation (4860 AM fungal propagules per plant) with seed coating (273 AM fungal propagules per seed) under greenhouse conditions.…”

Nematocidal Potential of Phenolic Acids: A Phytochemical Seed-Coating Approach to Soybean Cyst Nematode Management

“…As a result, attempts to elucidate the ecological (allelopathic, phytotoxic, anti-microbial) implications and direct/indirect roles of phenolic acids in the rhizosphere can be very challenging. Notably, various phenolic acids which are secreted as root exudates [ 59 , 74 ] can be readily metabolized by various soil microorganisms (bacteria, fungi) and, consequently, their presence can alter the diversity and composition of soil microbial communities resulting in the establishment of pathogenic or mutualistic interactions [ 29 , 75 , 76 , 77 , 78 ]. In soybeans for instance, various phenolic acids, such as benzoic acids, are exudated into the rhizosphere and can act as chemoattractants that facilitate quorum sensing activities in beneficial microbes, such as Rhizobium [ 70 ], which subsequently help protect against nematode infection ( M. incognita ) [ 29 ].…”

“…Notably, various phenolic acids which are secreted as root exudates [ 59 , 74 ] can be readily metabolized by various soil microorganisms (bacteria, fungi) and, consequently, their presence can alter the diversity and composition of soil microbial communities resulting in the establishment of pathogenic or mutualistic interactions [ 29 , 75 , 76 , 77 , 78 ]. In soybeans for instance, various phenolic acids, such as benzoic acids, are exudated into the rhizosphere and can act as chemoattractants that facilitate quorum sensing activities in beneficial microbes, such as Rhizobium [ 70 ], which subsequently help protect against nematode infection ( M. incognita ) [ 29 ]. Although these findings suggest phenolic acids may positively impact soybean–SCN interactions, there is very little evidence surrounding their physical/chemical interactions under highly variable field conditions to assess their agricultural implications.…”

“…The production of these defensive phytocompounds can be categorized as constitutive (phytoanticipins) or induced (phytoalexins) in which the presence of exogenous organisms or compounds can signal the induction of plant immune responses and defensive measures [ 4 , 20 , 21 ]. As global trends in pesticide use gradually shift away from conventional approaches, biopesticides and phytochemical pesticides are emerging as promising and more-sustainable alternatives [ 5 , 6 , 7 , 22 , 23 , 24 , 25 , 26 , 27 ] in conjunction with diverse application methods such as seed coating techniques [ 8 , 9 , 28 , 29 , 30 , 31 ]. Notably, the application of phytochemical or botanical nematicides [ 6 , 7 , 24 , 26 , 28 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ] has garnered increasing research interest due to their attractive qualities over conventional pesticides, such as lower toxicity, higher target specificity, lower environmental persistence, and biodegradability [ 6 ].…”