Management of bacteria Pectobacterium carotovorum, Xanthomonas campestris pv. carotae, and fungi Rhizoctonia solani, Fusarium solani and Alternaria dauci with silicon dioxide nanoparticles on carrot

Abstract

ABSTRACT Diseases of carrot (Daucus carota L.) that cause yield losses include bacterial soft-rot incited by Pectobacterium carotovorum pv. carotovorum (Jones) Waldee; bacterial leaf blight incited by Xanthomonas campestris pv. carotae (Pammel) Dowson; fungal leaf blight incited by Alternaria dauci (J.G. Kühn) J.W. Groves & Skolko; rot incited by Fusarium solani (Martius) Sacc., and crown rot incited by Rhizoctonia solani Kuhn. Nanoparticles are used to increase plant growth and provide protection against plant pathogens on various crops, but their effectiveness on carrot is not well understood. Effect of silicon dioxide nanoparticles (SiO2 NPs) after seed were primed, or applied to foliage, on inhibition of P. carotovorum, X. campestris pv. carotae, A. dauci, F. solani or R. solani, on growth, chlorophyll, carotenoid and proline contents of carrot were determined. Inoculation of plants with all pathogens reduced shoot and root dry weights, and chlorophyll and carotenoid contents over uninoculated controls. Inoculation of R. solani caused the greatest reduction (65.18%) in root dry weight and X. campestris pv. carotae the least (20.13%). Seed priming or foliar application with SiO2 NPs increased plant growth, and chlorophyll and carotenoid contents in inoculated plants, and the uninoculated control. Foliar application was better than seed priming in increasing growth, and chlorophyll and carotenoid contents of inoculated plants. The least increase in root dry weight (17.09%) was when plants derived from SiO2 NPs primed seed were inoculated with P. carotovorum, and the most was with foliar-applied SiO2 NPs against R. solani (85.29%). Individual inoculation of plants with pathogens caused increased proline content over the uninoculated control. Proline contents were further increased by the application of SiO2 NPs. Soft rot and bacterial blight index was 3 of 5 when plants were inoculated with P. carotovorum and X. campestris pv. carotae, respectively. Leaf blight/crown rot and root-rot indices were 4 of 5 when inoculation was with A. dauci, F. solani, and R. solani. Application of SiO2 NPs could be useful for the control of bacteria and fungi infecting carrot.