Abstract Weeds can be hosts of root-knot nematodes of the genus Meloidogyne. The importance of the species Meloidogyne morocciensis parasitizing many crops is recognized, but their reproductive capacity in weeds is not known. The present study hypothesizes the ability of M. morocciensis to parasitize and reproduce in different weed species found in Brazil. The objective was to evaluate the reproduction of M. morocciensis in 36 weed species. The plants were individually inoculated with 5,000 eggs and second stage juveniles and kept in greenhouse for 60 days. The experimental design was completely randomized with twelve replications. The root system of each plant was evaluated for gall index (GI), final nematode population (PF), number of nematode/g of root (NNGR) and reproduction factor (RF). It was verified that M. morocciensis has the capacity to parasite 36 weed species belonging to 16 different botanical families, confirming the hypothesis proposed. From the 36 species evaluated, 77.8% (28) were susceptible (FR ≥ 1.0) to M. morocciensis. The present study is the first to identify different weeds as hosts of M. morocciensis, evidencing its polyphagous habit, indicating species of plants with high capacity to multiply this nematode and that need more attention during the integrated management of these pathogen.

Abstract Meloidogyne javanica is among the most important nematodes that damage soybean, and although genetic resistance is the ideal control measure, there are few cultivars described as resistant among those recommended for southern Brazil. The objective of this work was to evaluate the reaction of soybean cultivars to M. javanica. The inoculum of nematodes (Est. J3) was obtained from soybean plants and inoculated into tomato plants cultivar “Santa Cruz”. Thirty-seven soybean cultivars widely used in the South, Southeast and Midwest of Brazil were used in the experiment. For each plant a suspension of 5,000 eggs + juveniles of second stage of M. javanica was inoculated into a sterile soil hole in 2-liter pots with six replications. The evaluation of root weight, number of galls, number of nematodes was 60 days after M. javanica inoculation. The results were subjected to analysis of variance, and the averages of each treatment were compared to each other by the Scott-Knott cluster test at 5% probability. Even though M. javanica presented RF> 1.00 in all soybean genotypes tested, different levels of susceptibility were observed. Thus, the lowest reproduction of the root-knot nematode was observed in M 5947 IPRO, HO AMAMBAY IPRO, BMX GARRA IPRO and FPS ATALANTA.

A cultura do feijão (Phaseolus vulgaris) tem a sua produtividade limitada por diversos fatores bióticos, sendo frequentemente afetada por nemátodes fitoparasitas. Várias espécies de nemátodes das galhas radiculares (NGR), Meloidogyne spp., têm sido encontradas e identificadas como sendo prejudiciais a esta cultura. Recentemente, Meloidogyne luci e Meloidogyne ethiopica foram reportadas como parasitas de feijoeiro no Brasil. O objetivo do trabalho foi avaliar, através da realização de ensaios de vaso, a reprodução de M. ethiopicae M. luci em vinte cultivares de feijoeiro. As plantas foram individualmente inoculadas com 5000 ovos + juvenis do segundo estádio (J2) de NGR e foram mantidas em estufa. Decorridos 60 dias da inoculação, as raízes de cada planta foram avaliadas quanto ao número de galhas, população final e fator de reprodução (FR=população final/população inicial). As médias das diferentes variáveis foram comparadas entre si pelo teste de agrupamento de Scott e Knott a 5%. Todas as cultivares de feijoeiro avaliadas comportaram-se como suscetíveis a ambos as espécies de NGR, com FR variando de 9,8 a 55,9 para M. ethiopica, e de 6,0 a 20,0 para M. luci.

The productivity of common bean crop is limited by several biotic factors, being often affected by plant-parasitic nematodes. Several species of root-knot nematodes (RKN), Meloidogyne spp. have been reported as damaging to the crop. Recently, Meloidogyne luci and Meloidogyne ethiopica were recorded parasitizing roots of common bean plants in Brazil. Therefore, the objective of this work was to evaluate the reproduction of M. ethiopica and M. luci on twenty bean cultivars. Plants were inoculated with 5,000 eggs plus second stage juveniles (J2) of RKN and pots were maintained in a greenhouse. Sixty days after inoculation, the roots of each plant were evaluated for number of galls, final population and reproduction factor (RF = final population / initial population) and the means of the different variables were compared by the Scott and Knott grouping test at 5%. Results showed that all tested cultivars were susceptible to both RKN, with RF ranging from 9.8 to 55.9 for M. ethiopica and from 6.0 to 20.0 for M. luci.

A adoção de práticas conservacionistas alteram as propriedades físicas, químicas e biológicas do solo, influenciando a composição da comunidade microbiana. O trabalho objetivou obter informação sobre a qualidade, diversidade e atividade biológica do solo, quando submetido a dois tipos de manejo do solo (plantio direto escarificado (PDE) e não escarificado (PDNE) e três tipos de manejo de cobertura (Sucessão: soja-trigo, Rotação I: soja-nabo+trigo/soja-aveia+ervilhaca/ e Rotação II: soja-aveia+ervilhaca+nabo/milho-crotalária juncea-trigo/soja). Foram analisadas a biomassa microbiana, atividade enzimática, taxa de respiração basal e diversidade genética do solo, nos períodos do verão (fevereiro/2016) e inverno (setembro/2016). O carbono e nitrogênio da biomassa microbiana foram superiores nos tratamentos sob PDNE. Todas as enzimas apresentaram incremento na atividade no período do verão. Para a respiração basal dos microrganismos, a menor taxa de CO2 acumulada foi no período do verão em solo sob PDNE. Detectou-se variabilidade genética através da técnica de Random amplified polymorphic DNA (RAPD), reunindo os tratamentos em quatro grupos. Pode-se concluir que o sistema PDNE associado à rotação de culturas contribui para aumentar a biomassa microbiana e atividade enzimática no solo. Além disso, a técnica de RAPD associada a outros bioindicadores tornam-se importantes ferramentas para o monitoramento da qualidade do solo.

The adoption of conservation practices affect the physical, chemical and biological properties of the soil, altering the composition of the microbial community. The objective of this research was to obtain information about the soil quality, diversity and biological activity, of the soil when submitted to two types of soil management (scarified (PDE) and no-scarified tillage (PDNE)) and three types of cover management (Succession: soybean-wheat, Rotation I: Soybean-turnip+wheat/soybean-oats+vetch and Rotation II: soybean-oats+vetch+turnip/corn-crotalaria juncea-wheat/soybeans). The microbial biomass, enzymatic activity, basal respiration rate and soil genetic diversity were analyzed during the summer (february/2016) and winter (september/2016) periods. The carbon and nitrogen of the microbial biomass were higher in treatments under PDNE. All enzymes showed an increase in the activity during the summer period. For the basal respiration of the microorganisms, the smallest accumulated CO2 rate was in the summer period under PDNE. The RAPD technique proved to be efficient in the detection of genetic variability, combining treatments in four groups. We concluded that PDNE associated with crop rotation contributes to increase the levels of microbial biomass and soil enzymatic activity. In addition, the RAPD technique associated with other bioindicators become important tools for the monitoring and evaluation of soil quality.