Interações entre Pratylenchus brachyurus e Meloidogynejavanica em soja

The interactive effects between Pratylenchus brachyurus and Meloidogynejavanica on soybean cv. Crista-Una were evaluated. Ten treatments (noninoculated check; single inoculations of P. brachyurus at three inoculum levels; single inoculations of M. javanica at two inoculum levels; and mixed inoculations of both species at four different combinations) were stablished, with five replications, in a randomized block design. Sixty days after the inoculations, fresh root weight and top dry weight values were determined, as well as the final population of the nematodes. Antagonism between the species was observed in the mixed infestations, being generally P. brachyurus more adversely affected. Significant reduction hi plant growth only occurred with single P. brachyurus inoculations of 5,000 or 10,000 nematodes per plant.Avaliaram-se os efeitos de interações entre Pratylenchus brachyurus e Meloidogynejavanica na soja 'Cristalina', sob condição de telado. Dez tratamentos (testemunha não inoculada; infestações simples de P. brachyurus em três níveis de inóculo; infestações simples de M. javanica em dois níveis de inóculo; e infestações conjuntas das duas espécies em quatro combinações de níveis de inóculo) foram estabelecidos, repetidos cinco vezes e arranjados em blocos casualizados. Após 60 dias das inoculações, determinaram-se os pesos de matéria fresca de raízes e matéria seca da parte aérea das plantas, bem como estimaram-se as populações finais dos nematóides. Observou-se antagonismo entre as duas espécies nas infestações conjuntas, sendo P. brachyurus geralmente a mais afetada. Reduções significativas nos pesos só ocorreram nas infestações simples de P. brachyurus nos níveis de 5000 e 10000 nematóides por planta

Comportamento de diversas plantas daninhas, de ocorrência comum no estado de São Paulo, em relação a duas espécies de nematóides das galhas: primeira parte

Estudou-se o comportamento de 10 espécies de plantas daninhas, comuns no Estado de São Paulo, quando o solo em que vegetavam foi inoculado com os nematóides das galhas Meloidogyne incognita raça 4 ou M. javanica. As avaliações foram feitas 50 dias após a inoculação dos parasitos, baseando-se nos números de galha s e ootec as pre sentes nas raízes e nos valores de altura e de pesos secos da parte aérea e sistemas radiculares das plantas. Em relação as duas espécies de nematóides, comportaram-se como alta mente suscetíveis Alternaria ficoidea (apaga -fogo) e Ipomoea acuminata (cordade -viola ), como olerantes Amaranthus hybridus var. patulus (caruru) e Commelina virgunica (trapoeraba), como pouco suscetível Euphorbia heterophylla (amendoim bravo) e como altamente resistentes Blainvillea rhomboidea (erva - palha), Crotonn glandulosus (gervãobranco), Emilia sonchifolia (serralha) e Tagetes minuta (cravo-de-defunto). O carrapicho-de-carneiro, Acant horpermum hispidum, mostrou-se altamente resis tente a M. incognita raça 4 e moderadamente suscetível a M. javanica.The behaviour of ten different weed species belonging to Amaranthaceae, Commelinaceae, Compositae, Convolvulaceae and Euphorbiaceae in relation to the root-knot nematodes Meloidogyne incognita race 4 and M. javanica was studied under greenhouse conditions. Evaluations were carried out 50 days after the nematode inoculations, by means of gall and egg masses indexes observed in the root systems and through the determination of height and/or top dry weight of the plants. Alternanthera ficoidea and Ipomoea acuminate were considered highly suscetible to both nematode species; Amaranthus hybridus var. patul us and Commelina virgunica were tolerant to the arasites whereas Euphorbia heterophylla showed low susceptibility; Acanthospernum hispidum was conside red moderately suscetible to M. javanica and highly resistant to M. incognita race 4; all other weeds - Blainvillea rhomboidea, Croton glandulosus, Emilia sonchifolia and Tagetes minuta - were highly resistant to the nematodes

Comportamento de diversas plantas daninhas, de ocorrência comum no estado de São Paulo, em relação a duas espécies de nematóides das galhas: segunda parte

Estudou-se o comportamento de dez espécies de plantas daninhas, comuns no Estado de São Paulo, quando o solo em que vegetavam foi inoculado com os nematóides das galhas Meloigodyne javanica (raça 4) ou M. javanica. As avaliações foram feitas 50 dias após a inoculação dos parasitos, baseando-se nos números de galhas e ootecas presentes nas raízes e nos valores de altura e de pesos secos da parte aérea e sistemas radiculares das plantas. Em relação às duas espécies de nematóides, comportaram-se como muito resistentes Brachiaria plantaginea, Cenchrus echinatus, Digitaria horizontalis e Elcusine indica. Cássia accidentalis, Cássia tora e Indigofera truxillensis mostraram baixa suscetibilidade enquanto Hyptis lophanta foi moderadamente suscetível. Leonotis nepetaefolia foi altamente suscetível e Echinochloa colonum tolerante aos parasitos

Carbon Partitioning In Soybean Infected With Meloidogyne Incognita And M. Javanica

Seven-day-old seedlings of two cultivars (Cristalina and UFV ITM1) of Glycine max were inoculated with 0, 3,000, 9,000, or 27,000 eggs of Meloidogyne incognita race 3 or M. javanica and maintained in a greenhouse. Thirty days later, plants were exposed to 14CO 2 for 4 hours. Twenty hours after 14CO 2 exposure, the root fresh weight, leaf dry weight, nematode eggs per gram of root, total and specific radioactivity of carbohydrates in roots, and root carbohydrate content were evaluated. Meloidogyne javanica produced more eggs than M. incognita on both varieties. A general increase in root weight and a decrease in leaf weight with increased inoculum levels were observed. Gall tissue appeared to account for most of the root mass increase in seedlings infected with M. javanica. For both nematodes there was an increase of total radioactivity in the root system with increased levels of nematodes, and this was positively related to the number of eggs per gram fresh weight and to the root fresh weight, but negatively related to leaf dry weight. In most cases, specific radioactivities of sucrose and reducing sugars were also increased with increased inoculum levels. Highest specific radioactivities were observed with reducing sugars. Although significant changes were not observed in endogenous levels of carbohydrates, sucrose content was higher than reducing sugars. The data show that nematodes are strong metabolic sinks and significantly change the carbon distribution pattern in infected soybean plants. 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