Allelopathic Effects of Hagonoy (Chromolaena Odorata L.) Leaf Extract and Leachate On Seed Germination and Early Growth of Selected Crops and Weeds

Abstract

INTRODUCTION

Hagonoy or gonoi (Chromolaena odorata) is a perennial sprawling weed that grows very rapidly and is highly competitive. Under the very dense canopy of a C. odorata thicket, light is scarce and other fast-growing species cannot survive. Slow-growing, shade-tolerant species are regularly bent to the ground by the continuous pressure of the growth of new C. odorata twigs on the upper layer of the thicket. It has a very efficient root system for capturing nutrients of which allopathic effects may also be involved This allelopathic effect is responsible for the observed inhibitory effect on the growth of adjacent plants contributing to its rapid colonization of the infested area.This allelopathic effect may be useful as a biological weed suppression or as a source of a new selective weed control agent. Thus, the researchers venture to undertake this study to assess the inhibitory and herbicidal potential of hagonoy (Chromolaena odorata Linn.) leaf extract and leachate.

METHODS

Varying amounts of the Chromolaena odorata Linn leaf extract were tested for allelopathic effects in three (3) crops namely; mung bean (Vigna radiata) , rice (Oryza sativa) and sesame (Sesamum indicum) and two (2) types of weeds: trilobed morning glory (Ipomoea triloba) and balatong aso (Cassia occidentalis Linn) while leaf leachate was tested for herbicidal potential in only two (2) types of weed: trilobed morning glory (Ipomea triloba) and pansit-pansitan (Pepperomia pellucida).

RESULTS

Results reveal that there is no significant difference in the mean growth of mung bean but a significant difference in the mean growth of rice, sesame seeds, trilobed morning glory, and balatong aso was noted. Significant differences in the mean length of roots of Ipomea trilob was noted, confirming the presence of growth inhibitors and indicating the potential use of C. odorata as a botanically-based herbicide.

DISCUSSIONS

Although no significant effect was established in terms of germination of crops and weeds and the growth of crops, the results of the study confirmed the presence of inhibitory activity on Chromolaena odorata. The inhibitor is present in the leaf and it is water-extractable. The extracted substance exhibit a growth regulatory property. As the amount of extract increases, the degree of inhibition also increases.