Abstract

FONSECA, Alysson Rodrigo; CRUZ, Ivan; CARVALHO, César Freire  and  SOUZA, Brígida. Resistance of sorghum genotypes to the corn leaf aphid Rhopalosiphum maidis (Fitch, 1856) (Hemiptera: Aphididae): III. Effect in plant development. Ciênc. agrotec. [online]. 2004, vol.28, n.3, pp. 585-592. ISSN 1413-7054.  http://dx.doi.org/10.1590/S1413-70542004000300014.

The objective of this work was to investigate in a greenhouse, the tolerance as a resistance mechanism of sorghum to the corn leaf aphid Rhopalosiphum maidis (Fitch) in experiments conducted in the National Corn and Sorghum Research Center of EMBRAPA, in Sete Lagoas, MG, Brazil. Eight sorghum genotypes, seven of them being known as resistant to the greenbug Schizaphis graminum (Rondani) and the commercial cultivar BRS303, were sown at a density of three seeds per pot with a capacity for 5 kg of soil. After emergence, a thinning was accomplished leaving only one plant, which was covered with a cylindrical cage, "voil''-coated. Eleven days after sowing, half of the pots were infested with 25 greenbug (adult aphids) per plant, whereas the other half was utilized as control. Weekly the height and fresh and dry weight at infested and non-infested plants were observed. The experimental design was completely randomized in split plot by allocating in the plots the genotypes and in the subplots the evaluation periods with ten replicates. It was found that genotypes 'GR 1.1.1.1.1', 'BRS303', 'IS2293', 'GSBTx399', 'TX430 (GR)' and 'TX2567' presented tolerance as a resistance mechanism, though it had been more evident in the three first ones genotypes.

Keywords : Sorghum; control method; resistance of plants to insects.