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Green corn: evaluation of earworm resistance, pericarp thickness and other agronomic characters

The varieties IAC Azteca Centenário, IAC Maya Latente, IAC-1 and IAC-VD 2 and the hybrid Cargill 742 and Agroceres 162 were evaluated for resistance to corn earworm, pericarp thickness and other agronomic characters, in a trial planted at May 1987 in the Pariquera-Açu Experimental Station, State of São Paulo, Brazil. The earworm infestation was estimated by the revised Widstrom scale and the presence of caterpillar exit holes in the husk. The kernel pericarp was measured with a comparative watch, using kernels soaked in glicerol solution and dried kernels. The other agronomic characters studied were: final stand, plant and ear height husk percentage of the ear; number, yield, total weight and medium weight of commercial ears; grain weight; and resistance to Exserohilum turcicum (Pass.) Leonard and Suggs. Except for the IAC-VD 2, all varieties were less productive than the hybrids. In relation to E. turcicum, Cargill 742, IAC Maya Latente and IAC-VD 2 were resistant Agroceres 162 was intermediated; and IAC-1 and IAC Azteca Centenário were susceptible. Similar results were obtained with the evaluation methods to lhe earworm infestation - revised Widstrom scale and presence of caterpillar exit hole in the husk. IAC Azteca Centenário and IAC Maya Latente were respectively the less and the more damage by corn earworm. Pericarp thickness was higher in the kernel side, where the differences among cultivars were also higher. Agroceres 162 and IAC Azteca Centenário had thicker pericarp.

green corn; varieties; hybrids; Heliothis zea; pericarp thickness; Exserohium turcicum


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