Statistical analysis.
The Bartlett’s test was used to test for homoscedasticity, following which data were subjected to analysis of variance (ANOVA). A two-way ANOVA with “shading level” and “harvest time” as fixed factors was used for STL profile, while a three-way ANOVA model “2 shading level × 2 harvest time × 4 extract concentration” was employed to evaluate the allelopathic activity in both wheat coleoptile and weed phytotoxicity bioassays. Means of STL data were separated by the Student–Neuman–Keuls test only when the F -test was significant at the 0.05 probability level. Wheat elongation data are expressed as percentage difference from the control. Zero ppm was also included in the statistical analysis.