Abstract
Even though oats (Avena spp.) have the capacity to produce numerous compounds with the potential to act antagonistically against plant pathogens, studies on the genotypic effect of this crop focusing on their nematicidal activity are limited. The objective of this study was to verify the effect of the aqueous extracts prepared with the biomass of oat genotypes, on the hatching of second-stage juveniles of root-knot nematodes (Meloidogyne javanica and Meloidogyne incognita). The bioassays were carried out in a completely randomized design with four replications. Eighteen extracts were evaluated, consisting of a combination of six oat genotypes Agro Quaraí, Agro Esteio, Embrapa 139, AF 12202, UPFPS Farroupilha, and AF 1345 Ucraniana, and three extract concentrations (5 %, 10 %, and 20 % w/v). Three additional treatments were added to the study (distilled water, chemical nematicides abamectin, and imidacloprid + thiodicarb). The treatments and the suspension containing nematode eggs were placed in Petri dishes and incubated in a growth chamber for ten days. At the 5 % and 10 % w/v concentration levels, a genotype effect was observed in the hatching of juveniles for both nematode species. For the control of M. javanica the extracts of Embrapa 139 had a better performance, while the extracts of Agro Quaraí and AF1345 Ucraniana performed better when under the control of M. incognita. Thus, oat biomass formation might have the ability to suppress the nematode population in the soil, and could therefore, be used for the management of root-knot nematodes.
Highlights
White oat (Avena sativa L.) and black oat (Avena strigosa Schreb.) are grown in numerous regions around the world as forage or cover crops, on account of their suitability for the intense production of dry matter for mulching
All extracts at 5 % w/v concentration exhibited lower efficiency in controlling the hatching of M. javanica juveniles, when compared to the three extract concentrations ( Table 2)
The efficiency in controlling the hatching of M. javanica was proven by the Embrapa 139 genotype, which showed no statistical differences across all three extract concentrations (Table 2)
Summary
White oat (Avena sativa L.) and black oat (Avena strigosa Schreb.) are grown in numerous regions around the world as forage or cover crops, on account of their suitability for the intense production of dry matter for mulching. A list of the main pests in agriculture would include root-knot nematodes (RKN) [Meloidogyne javanica (Treub) Chitwood and M. incognita (Kofoid & White) Chitwood]. These nematode species can cause severe damage to various agricultural crops worldwide (Karuri et al, 2017). Infection of nematodes in the host’s roots begins with second-stage juveniles and can lead to the formation of galls due to hyperplasia, which can result in reductions in water and nutrient uptake by the host plant. The infection results in underdeveloped plants with deficient production and in several cases they become totally unproductive (Escobar et al, 2015). The search for measures to control RKN is considered a matter of urgency
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