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Resumo -O objetivo deste trabalho foi avaliar a compatibilidade entre rizobactérias biocontroladoras pré-selecionadas e o efeito de suas combinações sobre a queima-das-bainhas (Rhizoctonia solani), a meloidoginose (Meloidogyne graminicola) e a promoção de crescimento de plantas de arroz. A compatibilidade foi determinada pela antibiose. O efeito das combinações de isolados foi avaliado por microbiolização de sementes de arroz, cultivar El Paso L144, com suspensões das rizobactérias DFs185 (Pseudomonas synxantha), DFs223 (P. fluorescens), DFs306 (ainda não identificada), DFs416 e DFs418 (Bacillus sp. Biocontrol of sheath blight and root-knot nematode and growth promotion of rice plants by rhizobacteriaAbstract -The objective of this work was to evaluate the compatibility between previously selected biocontroller rhizobacteria and the effect of their combination upon sheath blight (Rhizoctonia solani), root-knot nematode (Meloidogyne graminicola) and growth promotion in rice plants. The compatibility between these bacteria was determined by the overlay antibiosis. The effect of isolate combinations was evaluated by seed microbiolization of the rice cultivar El Paso L144 with rhizobacteria suspensions of DFs185 (Pseudomonas synxantha), DFs223 (P. fluorescens), DFs306 (unidentified), DFs416 and DFs418 (Bacillus sp.). These rhizobacteria were used alone or combined in arrangements of two, three and four isolates. The DFs223 isolate was not combined because it is incompatible with the other bacteria. Five rhizobacteria combinations (DFs185/418, DFs306/416, DFs306/418, DFs416/418, DFs185/306/418) and the isolate DFs306 stood out for reducing M. graminicola reproduction and promoting plant growth. Combination DFs185/306 presented the best results for the control of R. solani and for growth promotion. The DFs306/416 combination provided the best results for the control of the two diseases.Index terms: Meloidogyne graminicola, Rhizoctonia solani, biological control, seed microbilization, growth-promoting rhizobacteria. IntroduçãoVários microrganismos podem associar-se patogenicamente às plantas de arroz (Oryza sativa L.) e causar lesões na parte aérea e radicular, levando à redução da produção (Nunes et al., 2004 A queima-das-bainhas no arroz, causada por R. solani, ocorre em áreas temperadas e tropicais. Alguns fatores têm agravado sua incidência e severidade, como a utilização excessiva de adubação nitrogenada, alta densidade de plantas e plantio de cultivares de ciclo precoce, de baixa estatura, alto perfilhamento e de maior suscetibilidade. O cultivo do arroz sucedido por hospedeiros desse fungo leva à continuidade do ciclo do patógeno e ao aumento de inóculo (Nunes et al., 2004).

Soybean is a commodity of great economic importance worldwide, particularly in Brazil, world’s second largest producer. Nematodes, especially those of the Meloidogyne genus, severely limit productivity. Identification of nematode species is important for effective soybean management. Here, 26 populations of root-knot nematode (Meloidogyne spp.) from 15 municipalities in the states of Bahia, Mato Grosso, Goias, and Minas Gerais were characterized based on the morphology of the female perineal region, esterase profile, and identification based on amplification of specific regions of the population genome. Among the Meloidogyne spp. populations obtained, M. incognita and M. javanica, were identified. No mixed populations were present in the samples. Diagnosis based on molecular analysis was shown to be reliable and the fastest for characterization of nematode populations compared to other methods analyzed.

in the field, at the Universidade Federal de Minas Gerais -Montes Claros, Minas Gerais. There were two experiments: one with lettuce (Lactuca sativa L.) and other with carrot (Daucus carota L.) as main crops. Each one of them was conducted in a randomized block design, with seven treatments and six repetitions. The treatments were: single lettuce and in a group with basil (Ocimum basilicum L.) or mint (Mentha x villosa H.), single carrot and in a group with basil or mint, lettuce and carrot intercropping, and monoculture of basil and mint. The lettuce had two consecutive crops. In the first crop of lettuce only the variable fresh part of the aerial part was influenced by clustered culture. The form of cultivation did not affect the agronomic characteristics of the carrot. In the second crop of lettuce, there were better results in single growing. The highest productivity of the vegetables was observed in consortium cultivation. Key words: Lactuca sativa, Daucus carota, Mentha x villosa, Ocimum basilicum, intercroppingDesempenho agronômico de alface e cenoura, solteiras e consorciadas com plantas medicinais, em sistema orgânico RES UMOO objetivo deste trabalho foi avaliar o desempenho agronômico dos consórcios entre alface, cenoura, hortelã e manjericão, em sistema orgânico de produção. O experimento foi realizado de maio a setembro de 2007, em campo, na Universidade Federal de Minas Gerais -Montes Claros, MG. Foram realizados dois experimentos: um com a alface (Lactuca sativa L.) e outro com a cenoura (Daucus carota L.) como culturas principais. Cada um deles foi realizado no delineamento de blocos ao acaso, com sete tratamentos e seis repetições. Os tratamentos consistiram em: alface solteira e em consórcio com manjericão (Ocimum basilicum L.) ou com hortelã (Mentha x villosa H.), cenoura solteira e consorciada com manjericão ou com hortelã, consórcio alface e cenoura, e monocultivo de manjericão e hortelã. A alface teve dois cultivos consecutivos. No primeiro cultivo da alface apenas a variável massa fresca da parte aérea foi influenciada pelo cultivo consorciado. A forma de cultivo não influenciou as características agronômicas da cenoura. No segundo cultivo da alface foram observados melhores resultados no cultivo solteiro. As maiores produtividades das hortaliças foram observadas no cultivo em consórcio. v.4, n.3, p.283-288, jul.-set., 2009 Recife, PE, UFRPE. www.agraria.ufrpe.br Palavras-chave: Lactuca sativa, Daucus carota, Mentha x villosa, Ocimum basilcum, associação de culturas Revista Brasileira de Ciências Agrárias

Weeds can be hosting and alternative multipliers of root-knot nematodes ( Meloidogyne spp.). Among the main weeds, species of the genus Ipomoea stands out for their cosmopolitan presence and the negative impact on crops. In addition, they can behave as hosts and promote the reproduction of pests, diseases, and nematodes. However, the ability of Meloidogyne nematodes to infect morning-glory ( Ipomoea spp.) is little understood. In this context, the objective was to evaluate the reproduction of M. arenaria , M. enterolobii , M. ethiopica , M. hapla , M. incognita , M. javanica , M. luci , and M. morocciensis in I. grandifolia , I. hederifolia , I. nil , I. purpurea , and I. quamoclit. Plants were individually inoculated with 5,000 eggs and second-stage juveniles and kept in a greenhouse for 60 days. The design was completely randomized with six repetitions. After this period, the root system of each plant was evaluated to gall index (IG) and reproduction factor (RF). It was verified that the eight species of Melodoigyne have the capacity to parasitize I. grandifolia , I. hederifolia , I. nil , I. purpurea , and I. quamoclit , showing the susceptibility of these weeds to the plant-parasitic nematodes. The highest RF were observed for M. enterolobii with values of 12.5 and 12.9 for I. quamoclit and I. hederifolia , respectively. While M. arenaria obtained the lowest values, with RF ≤ 4.0 for all species of Ipomoea . Thus, weed species of the Ipomoea genus are potential hosts and multipliers of root-knot nematodes, making it important to be considered in integrated management strategies for these plant-parasitic nematodes.

Soybean crop productivity is limited by several biotic factors, particularly plant-parasitic nematodes. Several species have been reported to cause crop damage, especially those of the genus Meloidogyne. Therefore, the aim of this study was to evaluate, the reaction of 28 soybean genotypes to Meloidogyne arenaria and M. morocciensis in a greenhouse. The soybean genotypes were the same for experiments with different species of plant-parasitic nematodes and were individually inoculated with 5,000 eggs + second-stage juveniles (J2) of Meloidogyne and kept in a greenhouse. After 60 days of inoculation, the roots of each plant were assessed for the number of galls, final population, and reproduction factor (RF = final population/initial population). The averages of the different variables were then compared to each other by the Scott-Knott cluster analysis at a significance level of 5%. All of the soybean genotypes in the study were susceptible to both nematodes, with RF ranging from 3.5 to 24.1 for M. arenaria and 5.3 to 37.5 for M. morocciensis.

The root-knot nematode (Meloidogyne spp.) is the most important plant-parasitic nematode genus, they are the most common and destructive pathogens in this group. They produce some of the most drastic symptoms in plants and can significantly reduce the yield of crops. In order to achieve deploy an efficient method of plant-parasitic nematode management, is necessary an identification and quantification accurate and reliable of plant-parasitic nematodes. The aim of this study was to analyze samples in qPCR to detect and quantify M. incognita, in the field samples, comparing different methods of extraction of DNA and its efficacy in establishing the number of individuals. For this purpose the effectiveness of different DNA methods of extraction was compared through the values of CT intervals. For standard curve and method comparisons, we used nematodes multiplied in a greenhouse and carefully separated in the specific quantities of the experiments. For the number of individuals experiment field samples previously counted under an optical microscope were used. The DNA extraction was made from 100 nematodes by the methods: CTAB, Phenol: Chloroform and commercial kit (PureLink® Genomic DNA Kit, Invitrogen). In the comparative analysis using the three methods of DNA extracting from 100 nematodes, it was observed that commercial kit and CTAB methods obtained CT values similar. The CTAB method of extraction, showed less variation in the repeats and greater linearity of standard curve in comparison with other methods tested. So, it was possible to quantify the samples through the CT value intervals, established from different numbers of individuals (1, 10, 25, 100, 250, 500 and 750), in field samples. This study demonstrated that qPCR technique is an alternative sensitive and reliable for the quantification of M. incognita to support laboratories of diagnose and field survey.

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