บทคัดย่องานวิจัย

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Reaction of onion seeds and seedlings to Fusarium oxysporum f.sp. cepae and its relation to bulb basal rot.

Stadnik, M. J.; Dhingra, O. D.;

Fitopatologia Brasileira Year: 1995 Vol: 20 Issue: 3 Pages: 429-433 Ref: 14 ref.

1995

บทคัดย่อ

Reaction of onion seeds and seedlings to Fusarium oxysporum f.sp. cepae and its relation to bulb basal rot.

 

Influence of F. o. f.sp. cepae on plant growth parameters of 20 onion cultivars was studied in the lab. and in the greenhouse and was correlated to basal rot susceptibility during storage used to develop a rapid lab. technique for selection and improvement of existing cultivars for resistance to basal rot. Seeds were placed on blotter paper moistened with spore suspensions to determine the response of cultivars to seed germination reduction and seedling length reduction incited by the fungus. Hydroponic cultures in glass vials were used to determine the new root emission rate of 30-d-old inoculated seedlings. The traditional greenhouse technique was used to determine the influence of the fungus on plant height, leaf number and bulb infection. The seed germination reduction and seedling length reduction varied from 28 to 100% and from 33 to 100%, respectively, among the cultivars. The correlation coeff. between these parameters and basal rot susceptibility was insignificant. In the greenhouse tes

t cultivars differed significantly when compared for the pathogen-incited plant height and leaf number reduction up to 45 d after inoculation. On the 75th day, there was no significant difference among the cultivars and the inoculated plants could not be distinguished from the noninoculated controls. All the inoculated plants produced bulbs with an infected stem-plate. The coeff. of correlation between plant height or leaf number reduction and basal rot frequency was insignificant. In the hydroponic test, the cultivars differed significantly when compared for new root emission rate of the inoculated seedlings. The coeff. of correlation between root emission rate and basal rot frequency was highly significant. The inoculated seedlings of cultivars showing low basal rot frequency during a 90-d storage emitted more new roots than those showing high basal rot frequency. It is concluded that new root emission rate of 30-d-old inoculated seedlings, maintained in hydroponic culture for further 20 d, appears to be a

 good indicator of bulb susceptiblity to basal rot during storage.