Abstract:
:Allelopathy can be defined as a process involving secondary metabolites produced by
plants, micro-organisms, viruses, and fungi that influence the growth and development of agricultural
and biological systems (excluding animals), including positive and negative effects. The present study
was aimed at evaluating the allelopathic effects of straw of two rice varieties (B.G. 352 and B.G. 357)
and seven plant leaf extracts namely Calotropis procera, Cassia fistula, Cymborpogon nardus,
Eucalyptus sp., Lantana camara, Leucas aspera and Pinus sp. Four concentrations (05%, 10%, 15%
and 20% w/v) were tested for allelopathy {Seed Germination Percentage (SGP) and Seedling Vigor
Index (SVI)} on a weedy rice variety and four cultivated rice varieties namely AT 362 (Rosa Kekulu),
BG 39/16, Samba 365/3 and Sudu 400/2. The data obtained were analysed employing general linear
model ANOVA test using Minitab software 16.1.1 to detect the significance of differences at 5%
probability level. All tested plant species showed allelopathic effect and it was species and
concentration dependent as has been reported by others. Higher concentrations (15% ml and 20%)
inhibited SGP and SVI or either of all receiver plants and Calotropis procera and Eucalyptus sp. were
inhibitory on crop rice varieties too even at low concentrations (05% and 10%) and thus cannot be
considered for control of weedy rice in a paddy crop. Most of the other species significantly inhibited
the both SGP and SVI or only SVI and did not inhibit rice varieties indicating the possibility of
exploiting them for management of weedy rice and other weeds of paddy crops. Cassia fistula was
found to be the most promising candidate among tested plants.
