Influence of dry leaves of common tree and shrub species from southern Chile on the growth of lettuce infected with Meloidogyne hapla
Extracts of many plant species have shown nematicide activity attributable to phytochemicals present in their tissues or formed during a degradation process. Nevertheless, before the application of plant compounds in the field, it is necessary to know their effect on plant hosts. Three concentrations (1, 2.5 and 5% w/w) of dry leaves of Buddleja globosa, Drymis winteri, Eucalyptus globulus, Gevuina avellana, Laurelia sempervirens and Ugni molinae were evaluated on growth parameters (plant height, root length and leaf dry matter) in plants of Lactuca sativa infested with Meloidogyne hapla. Lettuce growth parameters were significantly affected by the interaction between the species and dry leaf tissues concentrations. Drymis winteri showed the biggest reductive effect on the evaluated parameters, but not significantly different as the effects from E. globulus. Independently of nematode infestation in lettuce plants, the incorporation of greater than 5% of dry leaves of D. winteri, E. globulus, G. avellana, L. sempervirens and U. molinae into the substrate had an important effect in the reduction of aerial biomass, estimating that the increase of dry leaf concentration explained about 60% of the reduction of this parameter. This suggests that the plant species evaluated have common active components with phytotoxic activity on lettuce plants, even though no complete information are available for concentrations, interactions and synthesis of derivatives during the degradation process of these tissues.