Bio-herbicidal effect of 5-aminoleveulinic acid producing rhizobacteria in suppression of Lathyrus aphaca weed growth

The present study evaluated the herbicidal potential of rhizospheric bacteria against Lathyrus aphaca L. weed in Indian mustard (Brassica juncea L.) crop. In primary screening, bacterial isolates HMM76, HMM109, HMM116, JMM24 and JMM44 were found to produce aminolevulinic acid ranging from 10.0 to 15.0 µg ml⁻¹ with HMM21, JMM11 and JMM35 producing more than 15 µg ml⁻¹. In secondary screening, ten bacterial isolates i.e., HMM21, HMM57, HMM76, HMM83, HMM109, HMM116, JMM4, JMM24, JMM35 and JMM44 showed a growth retardation effect on the 5th and 10th day after seed germination. Moreover, evaluation of screened bacterial isolates exhibiting different plant growth promoting traits such as indole acetic acid (IAA) production, phosphorus and potassium solubilization, 1-aminocyclopropane-1-carboxylate deamainase enzyme, and antagonistic activity against potential pathogens were used to conduct pot studies and found to cause significant reduction up to 92% in root and shoot dry weight of L. aphaca. The best performing culture, JMM24, was identified as Bacillus flexus by 16S rRNA sequence analysis. Therefore, these rhizospheric bacterial isolates could act as a potential candidate for suppression of weed growth under field conditions for their subsequent application as bioherbicide.