Allelochemical effects of Chromolaena odorata L. against photosynthetic pigments and stomata of Ageratum conyzoides l. leaves

The siam ( Chromolaena odorata L.) and babandotan ( Ageratum conyzoides L.) is weeds that often grow on cultivated land. Therefore it reduces crop productivity. Weeds are generally invasive because of an allelochemical compound that can inhibit the growth of existing plants around it. It is potential to be used as a bioherbicide to control weeds. This study aims to examine the allelochemical effects of different organs (leaf, stem, and root) of Chromolaena odorata L. at different concentrations on photosynthetic pigments and number of stomata on leaves Ageratum conyzoides L. The study used a Completely Randomized Design (RAL) and factorial pattern with two factors (3X5). The first factor is the type of organ siam, i.e., leaf, stem, and root and the second factor is the concentration of the extract, i.e., 0%, 10%, 20%, 30%, and 40%. Each treatment, replicated five times. The parameters measured were the concentration of photosynthetic pigments, i.e., chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids and the number of stomata. Results data were analyzed using Analysis of Variance (ANOVA) followed by Duncan’s Multiple Range Test (DMRT) at the test level of 95%. The results showed that root extract is more effective in reducing photosynthetic pigments and the number of stomata. Leaves Ageratum conyzoides L. than leaf and stem extracts, the higher concentration of the Siam weed extract, the greater inhibition was resulted