POTENTIAL OF PRAXELIS CLEMATIDEA (GRISEB.) R. M. KING & H. ROBINSON AS BIOHERBICIDES IN CONTROLLING SEED GERMINATION AND GROWTH OF ASYSTASIA GANGETICA (L.) T. ANDERSON WEED

• Main Author: Nuha Afifa, Inas
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71860
• Institution: Institut Teknologi Bandung

Palm oil is a leading plantation commodity that is important for the Indonesian economy. Palm oil maintenance activities, including weed control, also play a role in maintaining product stability. The fast growth rate of weeds, and competition for resources between palm oil plants and weeds can cause the quantity and quality of palm oil yields to decrease. Until now, many weed problems are overcome by the use of synthetic herbicides. However, the inappropriate application of synthetic herbicides causes resistance to Asystasia gangetica that is one of weed species in palm oil plantations. Therefore, alternative strategies through the use of bioherbicides need to be considered to support sustainable plantations. This research was conducted to evaluate the potential of Praxelis clematidea as a bioherbicide to control seed germination and growth of Asystasia gangetica. The research was carried out in 2 parts, namely the analysis of the active compounds found in Praxelis clematidea and bioassays of seed germination (pre-emergence) and growth (post-emergence) of Asystasia weed. Analysis of active compounds was carried out by phytochemical screening through tube tests (color, precipitate, and foam), and thin layer chromatography (TLC). Phytochemical screening in the tube test was carried out using the ImageJ-RGB program for flavonoids, alkaloids and terpenoids and foam distance for saponins. The TLC test was carried out on an aluminum silica gel plate as the stationary phase and ethyl-acetate:methanol, chloroform:methanol, and n-hexane:ethyl-acetate as the mobile phase. The formed spots were observed with a reagent and UV light at 254 and 366 nm. The bioassay experiment was carried out using Praxelis distilled water extract at a concentration of 25%, 50% and 75% with two kinds of controls, namely distilled water as a negative control and 3% diuron as a positive control. The seed germination bioassay was carried out in petri dishes that had been covered with cotton where the seeds were sprayed with 2 mL of Praxelis extract. Parameters observed were germination rate, mean germination time, and morphology of seeds and sprouts for three weeks. The seedling growth bioassay was carried out by spraying the sprouts grown on the soil with 2 mL of Praxelis extract. Parameters observed were number of leaves, growth rate, shoot and root length, shoot and root biomass, total chlorophyll content, and shoot condition for one week. The bioassay experiment was carried out using a completely randomized design (CRD) with 5 replications. Statistical analysis was performed using Kruskal Wallis and Pairwise Comparisons in the SPSS 26 program, then probit and logit regression in the Microsoft Excel program. The results showed that all parts of the Praxelis plant contained secondary metabolites from the phenolic, alkaloid and terpenoid groups. All concentrations of Praxelis extract used in this study had a significant effect on germination rate, mean germination time, number of leaves, growth rate, shoot and root length, shoot and root biomass, and total chlorophyll content of Asystasia. The LC50 value at pre-emergence was 9% (90 mL/L), post-emergence on the root-shoot was 25% (250 mL/L), post-emergence on the roots was 11% (110 mL/L), and post-emergence on the shoot was 37% (370 mL/L). Based on the results obtained, it can be concluded that Praxelis extract contains secondary metabolites from the phenolic, alkaloid and terpenoid groups which are toxic and have a significant effect on inhibiting the pre-emergence and post-emergence of Asystasia weeds. Thus, Praxelis clematidea has the potential as a bioherbicide to control seed germination and growth of Asystasia gangetica weed.