Biological management of selected weeds of wheat through co-application of allelopathic rhizobacteria and sorghum extract

Raza, T. and Yahya Khan, M. and Mahmood Nadeem, S. and Imran, S. and Nazir Qureshi, K. and Naeem Mushtaq, M. and Sohaib, M. and Schmalenberger, A. and Samuel Eash, N. (2021) Biological management of selected weeds of wheat through co-application of allelopathic rhizobacteria and sorghum extract. Biological Control, 164: 104775. ISSN 1049-9644

Abstract

Traditional methods of weeds management have caused serious environmental and health concerns. Therefore, development of alternate strategies for effective management of weeds is becoming indispensable for sustainable agriculture. In this study, the comparative effectiveness of chemical and bio-herbicides for the management of weeds in wheat has been assessed under laboratory and field conditions. Two effective allelopathic rhizobacteria (6 K and 6) were selected from initial screening experiment which had abilities to suppress the growth of selective weeds as well as had potential to improve the growth of wheat. Based on 16S ribosomal RNA (16S rRNA) gene sequencing, the selected allelopathic rhizobacteria were identified as Pseudomonas fluorescens strain 6 K and Bacillus sp. strain 6. Further, sorghum allelopathic water extract was also used in combination with selected allelopathic rhizobacteria as a bio-herbicide. Five treatments used for the laboratory and field experiments were control (T1: without herbicide), chemical herbicide (T2: mesosulfuron methyl + idosulfuron methyl; Atlantis® 6WG), sorghum allelopathic extract (T3), consortium of two different allelopathic rhizobacteria (T4) and combined application of allelopathic extract of sorghum and consortium of two allelopathic rhizobacteria (T5 = T3 + T4). Results of laboratory experiment showed that T5 significantly suppressed the seed germination percentage of four selected weeds i.e., Anagallis arvensis L., Phalaris minor Retz., Cynodon dactylon L. and Melilotus indicus L. and the same treatment (T5) also significantly improved seed germination of wheat as compared to all other treatments. Further evaluation under field condition showed that T5 significantly decreased the weed density and total weed biomass at 15, 30 and 45 days after sowing (DAS) of all weeds as compared to T1 (control). Field trial results also indicated that T5 significantly increased the wheat growth traits including the biological yield (73%) and grain yield (53%) as compared to T1. Likewise, the economic analysis revealed that T5 improved the net benefits with a higher marginal rate of return than all other treatments. Our findings indicated that combined application of allelopathic rhizobacterial consortium and allelopathic extract of sorghum remained more effective for controlling weeds and improving the growth and yield traits of wheat as compared to their sole application. Therefore, co-application of allelopathic rhizobacterial consortium and sorghum allelopathic water extract could offer an economically viable lever for the biological management of weeds of wheat for sustainable production.