Electronic Theses and Dissertation

Gulma merupakan tumbuhan pengganggu yang dapat menurunkan pertumbuhan dan hasil tanaman budidaya akibat persaingan dalam memperoleh air, unsur hara, cahaya, dan ruang tumbuh. Penggunaan herbisida sintetis secara terus-menerus dapat menimbulkan dampak negatif terhadap lingkungan sehingga diperlukan alternatif pengendalian yang lebih ramah lingkungan, salah satunya melalui pemanfaatan senyawa alelopati sebagai bioherbisida alami. Penelitian ini menggunakan etil asetat sebagai pelarut ekstraksi karena memiliki sifat semipolar, tingkat toksisitas yang rendah, serta mampu melarutkan senyawa yang bersifat polar maupun nonpolar. Penelitian ini bertujuan untuk mengetahui pengaruh aplikasi ekstrak etil asetat beberapa jenis gulma terhadap pertumbuhan gulma bayam duri (Amaranthus spinosus L.). Penelitian dilaksanakan di Laboratorium Ilmu Gulma, Laboratorium Farmakologi, Laboratorium Kimia Organik, dan Rumah Kaca Fakultas Pertanian Universitas Syiah Kuala pada bulan Desember 2025 hingga Februari 2026. Penelitian menggunakan Rancangan Acak Lengkap (RAL) nonfaktorial yang terdiri atas 18 perlakuan dan 3 ulangan. Perlakuan terdiri atas kontrol negatif (akuades), kontrol positif (2,4-D 0,686 kg b.a ha⁻¹), serta ekstrak etil asetat kirinyuh (Chromolaena odorata L.), alang-alang (Imperata cylindrica L.), teki (Cyperus rotundus L.), dan paitan (Axonopus compressus L.) pada konsentrasi 5%, 10%, 15%, dan 20%. Hasil penelitian menunjukkan bahwa aplikasi ekstrak etil asetat beberapa jenis gulma berpengaruh sangat nyata terhadap tinggi gulma, jumlah daun, bobot basah dan bobot kering, luas daun, dan persentase pengendalian gulma bayam duri. Perlakuan terbaik diperoleh pada ekstrak etil asetat teki konsentrasi 5% yang mampu memberikan persentase pengendalian gulma sebesar 98,33%, diikuti ekstrak etil asetat paitan 5% dengan persentase pengendalian 92,33% dan ekstrak etil asetat alang-alang 5% dengan persentase pengendalian 52,33% pada 7 hari setelah aplikasi (HSA). Ekstrak etil asetat kirinyuh pada konsentrasi 5% menunjukkan efek stimulatif terhadap pertumbuhan gulma bayam duri. Hasil uji fitokimia menunjukkan bahwa ekstrak etil asetat teki mengandung alkaloid, terpenoid, saponin, flavonoid, tanin, dan fenolik; ekstrak etil asetat kirinyuh dan paitan mengandung alkaloid, steroid, flavonoid, tanin, dan fenolik; sedangkan ekstrak etil asetat alang-alang mengandung alkaloid, saponin, tanin, dan fenolik. Berdasarkan hasil penelitian, ekstrak etil asetat teki berpotensi dikembangkan sebagai bioherbisida alami untuk pengendalian gulma bayam duri.

Weeds are intrusive plants that can reduce the growth and yield of cultivated crops due to competition for water, nutrients, light, and growing space. Continuous use of synthetic herbicides can have negative environmental impacts; therefore, more eco-friendly control alternatives are needed, such as the utilization of allelopathic compounds as natural bioherbicides. This study employed ethyl acetate as the extraction solvent due to its semi-polar nature, low toxicity, and ability to dissolve both polar and non-polar compounds. The research aimed to determine the effect of applying ethyl acetate extracts from several weed species on the growth of spiny amaranth (Amaranthus spinosus L.). The study was conducted at the Weed Science, Pharmacology, and Organic Chemistry Laboratories, as well as the Greenhouse of the Faculty of Agriculture, Syiah Kuala University, from December 2025 to February 2026. A non-factorial Completely Randomized Design (CRD) was used, comprising 18 treatments and 3 replications. The treatments included a negative control (distilled water), a positive control (2,4-D at 0.686 kg a.i. ha⁻¹), and ethyl acetate extracts from Chromolaena odorata L., Imperata cylindrica L., Cyperus rotundus L., and *Axonopus compressus* L. at concentrations of 5%, 10%, 15%, and 20%. The results indicated that the application of ethyl acetate extracts from the tested weed species had a highly significant effect on weed height, leaf number, fresh and dry weight, leaf area, and the percentage of control of Amaranthus spinosus L. The best results were obtained with the 5% concentration of teki (nutgrass) ethyl acetate extract, which achieved a weed control rate of 98.33%, followed by the 5% paitan (Mexican sunflower) extract (92.33%) and the 5% alang-alang (cogon grass) extract (52.33%) at 7 days after application (DAA). The 5% kirinyuh (Siam weed) ethyl acetate extract exhibited a stimulatory effect on the growth of spiny amaranth weeds. Phytochemical analysis revealed that the teki extract contained alkaloids, terpenoids, saponins, flavonoids, tannins, and phenolics; the kirinyuh and paitan extracts contained alkaloids, steroids, flavonoids, tannins, and phenolics; while the alang-alang extract contained alkaloids, saponins, tannins, and phenolics. Based on these findings, the teki ethyl acetate extract has the potential to be developed as a natural bioherbicide for controlling spiny amaranth weeds.