Abstract:
A study was undertaken to examine allelopathic effect of chilli, rice and okra extracts
on germination and growth of Eleusine indica under laboratory environments besides
studying the allelopathic effect of crop residue-applied sterilized and non-sterilized
soil on growth of E. indica under greenhouse conditions. The most phytotoxic extract
were chilli leave, followed by chilli stem which fully inhibited the seed germination at
20 and 30 g L·', respectively. Chilli leave and chilli stem extracts inhibited the
seedling growth but the okra pod and rice straw-plus-leave extracts had no effect on
seedling growth under laboratory conditions. The chilli stem and chilli leave extracts
had equally high allelopathic effects which caused growth inhibition to 38.2 and 54.6
%, respectively. The crop residues showed less allelopathic effects on seedling height
except the seedlings treated with okra pod residue and grown using sterilized soil. The
height of weed seedling was significantly reduced to 69.3 % by okra pod residue at
1.0 ton ha·1, while the seedling fresh weight was reduced by 60.2 % in comparison to
control. The fresh weights of rice straw-plus-leave applied seedlings that grown using
sterilized soil and seedlings of all treatments that were grown using non-sterilized soil
were stimulated as the concentrations of crop residues increased, with the fresh
weights of rice straw-plus-leave and chilli leave residues applied seedlings being
increased by 41.5% and 69.4 %, respectively. This study suggests that all the crops
extracts and crops residues exhibit the allelopathic effects on germination and seedling
growth of E. indica depending on seedling age, duration of residues decomposition,
compounds presence and the soil conditions. However, only chilli extract and okra
residue show potent herbicidal activity.
