Auro Akio Otsubo

Sistemas de preparo do solo, plantas de cobertura e produtividade da cultura da mandioca

O objetivo deste trabalho foi avaliar os efeitos do uso de plantas de cobertura e de sistemas de preparo do solo, no desenvolvimento e na produtividade da cultura da mandioca (Manihot esculenta Crantz). O trabalho foi conduzido em Argissolo Vermelho, sob sistema convencional de preparo do solo, e em cultivo minimo sobre palhada de mucuna-cinza (Stizolobium cinereum Piper & Tracy), sorgo granifero [Sorghum bicolor (L.) Moench] e milheto [Pennisetum americanum (L.) K. Schum.]. Aos dezoito meses apos o plantio da mandioca, foram avaliados: altura de plantas, producao de massa de materia seca da parte aerea, numero de raizes tuberosas, produtividade, percentagem de materia seca e de amido nas raizes tuberosas e indice de colheita. Observou-se que o sistema convencional de preparo do solo pode ser substituido, na cultura da mandioca, pela pratica do cultivo minimo, associada ao uso de coberturas vegetais, por promover incrementos significativos na produtividade da cultura, especialmente, quando se utiliza o milheto como planta de cobertura. O uso de plantas de cobertura no pre-cultivo de mandioca, em sistema de preparo minimo do solo, representa uma alternativa eficiente para um melhor manejo dessa cultura.

Performance de cultivares de mandioca e incidência de mosca branca no Vale do Ivinhema, Mato Grosso do Sul

The Ivinhema Valley is the most important region for cassava production in State of Mato Grosso do Sul. However, the restricted number of cultivars available for this region contributes for the occurrence of low yields and increasing diseases and pests. The objective of this study was to evaluate the performance of cassava genotypes in the region of Ivinhema Valley. The experiments were conducted from July/2005 to September/2006, in Nova Andradina, Ivinhema and Deodapolis in a randomized complete block design, with four replications. Yield components and resistance to sooty mould caused by whiteflies (Bemisia sp.) were evaluated in 11 cassava cultivars. It was found that the cultivars IAC 12 and Fecula Branca were the most resistant to sooty mould incidence. Cv. Cascuda showed the largest yield of storage roots and dry matter in all tested environments.

Diversidade da fauna edáfica e epigeica de invertebrados em consórcio de mandioca com adubos verdes

The objective of this work was to evaluate the density and diversity of epigeic and edaphic invertebrate fauna in a cultivation of cassava intercropped with green manures. The study was carried out in soil cultivated with cassava (C) intercropped with jack-beans (JB), millet (MI), and pigeon pea (PP), in comparison with the traditional system of cassava cultivation (TS) without cover species. Invertebrates of the epigeic fauna were collected using pitfall traps and those of the edaphic fauna were collected in soil monoliths. Among the epigeic invertebrates, the Collembola, Diptera, and Formicidae groups were dominant in all intercropping, accounting for over 80% of total relative frequency (RF), while in the soil fauna the Isoptera group was dominant in all intercropping, with the highest RF for the C+PP intercropping (90.2%), followed by C+JB (83.1%) and C+MI (65.6%), and the lowest RF occurred for TS (32%). The number of individuals of the epigeic fauna did not vary among the intercropping systems; however, the number of organism groups varied significantly. The C+MI intercropping showed the greatest richness of groups. The total density of organisms of the edaphic soil fauna varied among intercropping systems, and the highest density was observed in C+PP, in comparison to TS. The edaphic and epigeic fauna invertebrates respond to changes, favored by the intercropping green manure with cassava, by increasing group diversity.