Interactions between a plant growth-promoting rhizobacterium and smoke-derived compounds and their effect on okra growth

HEINO B. PAPENFUS; MANOJ G. KULKARNI; WENDY A. STIRK; KANNAN R. R. RENGASAMY; M. VICTORIA SALOMON; PATRICIA PICCOLI; RUBÉN BOTTINI; JOHANNES VAN STADEN

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE-ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2015 vol. 178 p. 741 - 747

1436-8730

Plant growth-promoting rhizobacteria (PGPR) are used in agriculture to improve crop yield.Crude smoke water (made by bubbling plant-derived smoke through water) stimulates germination and improves seedling growth. Some active compounds have been isolated from smoke with karrikinolide (KAR1) stimulating plant growth and trimethylbutenolide (TMB) being inhibitory. These smoke compounds have great potential in agriculture but their interaction with PGPR is unknown. In the present study, a two-factorial pot trial with three replicates per treatment was designed to investigate the interactions between Bacillus licheniformis and two concentrations each of smoke water, KAR1, and TMB on okra (Abelmoschus esculentus). Growth and physiological parameters (chlorophyll, carotenoid, protein, sugar and a-amylase) of okra as well as bacterial abundance in the rhizosphere were measured after 5 weeks. Application of B. licheniformis and 10?7 M KAR1 significantly improved the shoot biom ass and 10?7 M KAR1 also significantly improved leaf area of okra. However, when 10?7 M KAR1 was applied in combination with B. licheniformis, there was an antagonistic effect on plant growth. While TMB had a negative effect on plant growth, a combination treatment of TMB and B. licheniformis overcame the inhibitory effect of TMB resulting in plant growth similar to the control plants. All treatments had noeffect on chlorophyll, carotenoid, protein and sugar concentrations while a-amylase activity was significantly elevated in okra root treated with 1:500 v/v smoke?water. Determining the rhizobacteria populations at harvest showed that all treatments had no significant effect on the rhizosphere microbial abundance. The modes of interaction between PGPR and smoke-derived compounds need to be further elucidated.