Efeito de pré-cultivos sobre o potencial de inóculo de fungos micorrízicos arbusculares e produção da mandioca

Abstract

RESUMO -Avaliou-se o efeito de pré-cultivos com adubos verdes sobre o potencial de inóculo de fungos micorrízicos arbusculares e produção de mandioca (Manihot esculenta, Crantz). O experimento foi conduzido no campo experimental da Embrapa-Centro Nacional de Pesquisa de Agrobiologia (CNPAB), em solo Podzólico Vermelho-Amarelo, localizado no Município de Seropédica, RJ, em parcelas experimentais de 30 m 2 , dispostas em delineamento de blocos casualizados com quatro repetições. Os pré-cultivos constaram de Canavalia ensiformis, Mucuna aterrima, Crotalaria juncea, Cajanus cajan e Sorghum bicolor (BR 005) e o tratamento-controle (solo mantido sem plantas). Após um período de 82 dias de crescimento, sobre as mesmas parcelas cultivou-se mandioca, por oito meses. A produtividade de raízes de mandioca variou de 12,76 a 17,20 t ha -1 , porém não foi detectada diferença estatística entre os tratamentos. Foram identificadas 16 espécies de fungos micorrízicos arbusculares e foi constatado que o número de esporos de algumas espécies sofreu alteração da sua freqüência de ocorrência com os cultivos. O pré-cultivo com sorgo aumentou o número de propágulos infectivos em relação ao controle, demonstrando que o uso de espécies de plantas com capacidade para elevar o potencial de inóculo pode ser um bom caminho alternativo para resolver o problema de produção de inóculo para culturas micotróficas em campo. Termos para indexação: Manihot esculenta, Canavalia ensiformis, Mucuna aterrima, Crotalaria juncea, Cajanus cajan, Sorghum bicolor, número de esporos, propágulos infectivos. EFFECT OF PRE-CROPS ON THE INOCULUM POTENTIAL OF ARBUSCULAR MYCORRHIZAL FUNGI AND CASSAVA YIELDABSTRACT -The effect of pre-crops on the inoculum potential (IP) of arbuscular mycorrhizal fungi (AMF) and yield of cassava was evaluated on a Red-Yellow Podzolic soil in the field. The experiment was carried out at Embrapa-Centro Nacional de Pesquisa de Agrobiologia (CNPAB), Seropédica, RJ, Brazil, in plots with 30 m 2 arranged in a randomised block design with four replications. As pre-crops, four legume species were used: Canavalia ensiformis, Mucuna aterrina, Crotalaria juncea and Cajanus cajan; and a grass Sorghum bicolor (BR 005) in relation to plots, without plants. After a grow period of 82 days, at the same plots, cassava stakes were planted, which were grown for eight months. The yield of cassava roots ranged from 12.76 to 17.20 ton ha -1 , although no statistical significant effects were found between the treatments. There were 16 AMF species identified, and some of them had a significant frequency changement after the growing cycles. The number of infective propagules were significantly increased after sorghum crop in relation to plots without plants. It was showed that identification of plant species capable to increase the IP in the field soils may be a good alternative way to solve the problem of inoculum production to mycotrophic crops in the field.

Occurrence and Structure of Arbuscular Mycorrhizal Fungal Communities in Cassava after Cultivation of Cover Crops as Observed by the “PCR-DGGE” Technique

“…In a cassava crop area after 82 days of pre-cultivation with legumes and sorghum, Souza et al (1999) reported the occurrence of 16 AMFs species, with the genus glomus showing the highest frequency. In addition, the authors found that pre-cultivation of sorghum resulted in significant increases in the number of AMFs propagules in the soil, a similar behavior observed for oats (monocropped or intercropped) in the present study.…”

“…Therefore, the multiplying property of cover crops is an alternative for increasing the inoculum potential of AMFs in the soil (Souza et al, 1999), thus bringing benefits to successive crops of cassava. Legumes and grasses are some of the plant species that contribute most to multiplication of AMFs in the soil, whereas other common cover crops, such as oilseed radish, are non-mycotrophic (Gomide et al, 2009).…”

Alterations in Root Morphology of Rootstock Peach Trees Caused by Mycorrhizal Fungi

“…Plants with greater height and leaf area, are more light-gathering capacity and production of assimilates, which allows a higher flow of carbohydrates into the root system where one part would be used by the AMF in its nutrition and accumulation in structures buffer (vesicles, where Acaulospora sp. and G. etunicatum), and the rest would be accumulated in the storage tissue of the plant in the form of reserve substances (Souza et al, 1999;Scatena & Scremin-Dias, 2003). Moreover, the larger diameter provided by the AMF, would increase the upward flow of water and nutrients, and sap formulated in the downward (Mazzoni-Viveiros & Trufem, 2004).…”

Sporocarpic species of arbuscular mycorrhizal fungi (Glomeromycota), with a new report from Brazil

“…Material (Bononi & Trufem 1983;Trufem & Bononi 1985;Trufem et al 1989;Maia & Trufem 1990;Trufem & Viriato 1990;Trufem et al 1994;Trufem 1995;Trufem & Malatinszki 1995;Souza et al 1999;Carrenho & Trufem 2001;Souza et al 2003;Yano-Melo et al 2003). Sporocarps red brown at the light microscope and dark brown at the stereomicroscope, hemispheric to spheric (814-)653×571(-499) µm, with thick peridium (56.4 µm).…”