Electronic Theses and Dissertation

Penggunaan herbisida sintetis dalam pengendalian gulma sering menimbulkan dampak negatif seperti resistensi gulma, pencemaran lingkungan, dan gangguan kesehatan. Oleh karena itu, diperlukan alternatif pengendalian gulma yang ramah lingkungan berupa bioherbisida yang bersumber dari senyawa alelopati tanaman. Salah satu tanaman yang berpotensi adalah babadotan (Ageratum conyzoides L.) yang diketahui mengandung metabolit sekunder dengan aktivitas alelopatik. Penelitian ini menggunakan metode uji terpandu (bio guided fractionation) Penelitian ini diawali dengan menggunakan metode ekstraksi pelarut n-heksana, dilanjutkan dengan isolasi dan re-isolasi menggunakan kromatografi kolom dan diperoleh sub-subfraksi A1, A2, dan A3, dan pada penelitian ini yang diuji adalah sub-subfraksi A3, selanjutnya dianalisis dengan uji fitokimia, serta analisis GC-MS dan diuji aktivitasnya pada gulma bayam duri (Amaranthus spinosus L.). Penelitian ini berlangsung dari Mei 2024 sampai dengan Februari 2025. Penelitian ini dilaksanakan di Laboratorium Ilmu Gulma, Departemen Agroteknologi Fakultas Pertanian, Laboratorium Analisis Pangan Departemen Teknologi Hasil Pertanian Fakultas Pertanian, Ruang Analisis Sampel Jurusan Kimia Fakultas Matematika dan Ilmu Pengetahuan Alam, Laboratorium Kimia Organik Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Syiah Kuala dan Kebun Percobaan Fakultas Pertanian Universitas Syiah Kuala, Banda Aceh. Rancangan percobaan menggunakan Rancangan Acak Lengkap (RAL) pola non faktorial dengan lima perlakuan, yaitu kontrol (aquades) dan ekstrak sub-subfraksi A3dengan konsentrasi 0,5%, 1%, 1,5%, dan 2%, masing-masing diulang tiga kali. Parameter yang diamati meliputi tinggi tanaman gulma bayam duri, jumlah daun gulma bayam duri, luas daun gulma bayam duri, panjang akar gulma bayam duri, berat basah dan berat kering gulma bayam duri, serta persentase pengendalian gulma bayam duri. Hasil penelitian menunjukkan bahwa ekstrak konsentrasi terbaik pada ekstrak n-heksana babadotan sub-subfraksi A3 yaitu konsentrasi 1,5% memberikan efek paling optimal dengan menghambat pertumbuhan gulma bayam duri hingga mencapai kematian 100% pada 7 hari setelah aplikasi. Uji fitokimia mengidentifikasi keberadaan alkaloid dan terpenoid, sementara analisis GC-MS menemukan 37 senyawa dengan 4 senyawa mayor yaitu 4-Oxo-ß-isodamascol, 1-Heneicosyl formate, Neophytadiene, dan Phytol.

The use of synthetic herbicides in weed control often causes negative impacts such as weed resistance, environmental pollution, and health problems. Therefore, environmentally friendly weed control alternatives in the form of bioherbicides derived from plant allelopathic compounds are needed. One plant with high potential is billygoat weed (Ageratum conyzoides L.), which is known to contain secondary metabolites with allelopathic activity. This study employed a bio-guided fractionation method. The research began with extraction using n-hexane as a solvent, followed by isolation and re-isolation through column chromatography, resulting in sub-subfractions A1, A2, and A3. In this study, sub-subfraction A3 was selected for further evaluation, including phytochemical screening, GC–MS analysis, and bioherbicidal activity testing against spiny amaranth (Amaranthus spinosus L.). The study was conducted from May 2024 to February 2025 at the Weed Science Laboratory, Department of Agrotechnology, Faculty of Agriculture; Food Analysis Laboratory, Department of Agricultural Product Technology, Faculty of Agriculture; Sample Analysis Room, Department of Chemistry, Faculty of Mathematics and Natural Sciences; Organic Chemistry Laboratory, Faculty of Mathematics and Natural Sciences; and the Experimental Field of the Faculty of Agriculture, Syiah Kuala University, Banda Aceh. The experiment was arranged in a completely randomized design (CRD) with a non-factorial pattern consisting of five treatments: control (distilled water) and sub-subfraction A3 extract at concentrations of 0.5%, 1%, 1.5%, and 2%, with three replications each. Observed parameters included plant height, number of leaves, leaf area, root length, fresh weight, dry weight, and percentage of weed control of spiny amaranth. The results showed that the most effective concentration of the n-hexane extract of billygoat weed sub-subfraction A3 was 1.5%, which provided the most optimal effect by inhibiting the growth of spiny amaranth and causing 100% mortality at 7 days after application. Phytochemical analysis identified the presence of alkaloids and terpenoids, while GC–MS analysis detected 37 compounds, with four major compounds identified as 4-Oxo-β-isodamascol, 1-Heneicosyl formate, Neophytadiene, and Phytol.