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Avaliação da resistencia de progenies de tomate a murcha bacteriana em solo naturalmente infestado por Pseudomonas solanacearum (Smith) dows (Evaluation of the resistance of tomato progenies to bacterial wilt in soil naturally infested with Pseudomonas solanacearum (Smith) dows)

Hiroshi Noda^I; Alejo Von der Pahlen^II; Danilo Fernandes da Silva-Filho^I

^IDepartamento de Ciências Agronômicas, Divisão de Genética e Melhoramento, Instituto Nacional de Pesquisas da Amazônia - INPA, Caixa Postal 478, 69000 Manaus, AM, Brasil. Send correspondence to H.N.
^IICrops and Grassland Service, FAO, Rome, Italy

ABSTRACT

The bacterial wilt caused by Pseudomonas solanacearum limits tomato production in the Amazon region. The purpose of the present study was to evaluate thc: resistance and yield capacity of 10 tomato progenies cultivated in soil naturally infested with Pseudomonas solanacearum. The experiment was conducted on infested soil at "Estação Experimental de Hortaliças do INPA" (AM-010, Km. 14), in Manaus.
The resistance reaction was evaluated by the epidemiological parameter Infection Rate (QR), described by Plank (1963) for disease without multiplication and by the Disease Index (D.I.), based on the number of infected plants in the plot. Eight and six progenies showed greater resistance than the control cultivar Santa Cruz São Sebastião when the evaluation criterion was QR or when the evaluation by D.I. was performed at the 12th week after transplantation, respectively. Yield data expressed as weight, number and mean fruit weight, showed that at least five progenies were superior to the control, depending on the evaluation criterion used. The correlation coefficients estimated for all pairs of resistance and productive traits were statistically significant, except for the D.I. pair at the 4th week after transplantation and mean fruit weight.
Under the conditions used in the present experiment, bacterial wilt showed a well defined epidemiological characteristic, in which the high resistance level conferred by a genotype was due to the slow progress of disease in the host population.

Keywords: tomato; bacterial wilt; Pseudomonas solanacearum.

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