Allelopathic effects of nine leaf extracts including rice straw on weedy rice and four rice varieties

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.