Inhibitory and stimulative effects of Lantana camara L. leaves on Lycopersicum esculentus and Lactuca sativa seedlings

Abstract

The study was carried out to determine the allelopathic effects of these mulches on germination and early growth of Lycopersicum
esculentus and Lactuca sativa which are common vegetables in Zimbabwe. Laboratory and greenhouse experiments were
conducted. A laboratory experiment with six treatments: 0, 1, 2, 3, 4 and 5 % aqueous concentration of Lantana camara leaf
extracts was set up in the laboratory and was replicated three times and repeated twice over time. A greenhouse experiment in
which L. camara dry matter was incorporated into the soil with 0, 1, 10, 20, 30, 40 and 50 grammes per pot of dry leaf biomass
replicated three times and repeated twice over time ws also set up. The results indicated that Lantana leaf extracts significantly
reduced (P<0.05) the germination, radicle length and plumule length of tomatoes but not for plumule length for lettuce. The level of
inhibition was positively correlated to the concentration of the Lantana extracts on both vegetables. However, in the greenhouse,
biomass of both vegetables was not affected by increase in Lantana concentration up to 40 g/pot. In this study, inhibitory effects of
Lantana were observed in the laboratory but not in the green house where ground leaf biomass was mixed with red clay soil with a
clay content of 33.5 %. The dry matter of lettuce increased with increase in L camara up to 30 g/pot and then decreased. For
tomatoes, it increased up to 40g/pot and then decreased raising the possibility of using reduced lantana camara rates to stimulate
dry matter accumulation for both tomatoes and lettuce.