Effectiveness of Citronella Oil Nanoemulsion on Phytophthora palmivora Butl. Black Pod Pathogen

Abstract
Description
Black pod disease caused by Phytophthora palmivora is a significant disease on cocoa crops worldwide. Citronella and geraniol are two dominant substances of citronella oil that have fungicidal activity, which is potentially used to control black pod disease. However, those two substances are relatively unstable form volatile. To improve stability can be done using nanotechnology. The study aimed to analyze the effectiveness of citronella-oil-nanoemulsions formulas on the growth of P. palmivora in vitro and on cocoa pods.  Eight nano formulas were prepared at the Postharvest Center in Bogor; however, the effectiveness was conducted at the Indonesian Industrial and Beverage Crops Research Institute in Sukabumi. The nano formula was prepared following spontaneous, simultaneous, and inversion methods.  The experiments were designed in a completely randomized design, with five replications.  Eight treatments were evaluated, i.e., the inversion formulas (F1, F2, F5 & F7), spontaneous (F3, F6 & F8), and simultaneous (F4). Two concentration levels of the formula were tested, i.e., 0.5% for in vitro and 1.0% in cacao pods. The variables observed were the inhibition rate of formula, bioassay, concentration, and inhibition rate on cacao pods. The nanoemulsion formulas of citronella oil could inhibit 23.13%–77.78% of the growth of P. palmivora. Formula F5 was the best, which inhibited 77.78% growth in vitro and 31.60% in cacao pods. The nanoemulsions of citronella oil affected the growth rate, fresh weight, and dry weight of P. palmivora. For better effectiveness of the formula on cocoa pods, the concentration should be increased.
Penyakit busuk buah yang disebabkan oleh Phytophthora palmivora merupakan penyakit utama pada tanaman kakao di seluruh dunia. Pengendalian P. palmivora dapat menggunakan minyak serai wangi karena mengandung bahan aktif sitronella dan geraniol yang bersifat fungisidal. Bahan aktif dari minyak serai wangi mudah menguap sehingga dapat menurunkan keefektifannya. Stabilitas minyak serai wangi dapat ditingkatkan dengan menggunakan teknologi nano. Tujuan penelitian adalah menganalisis efektivitas formula nanoemulsi minyak serai wangi terhadap Phytophthora palmivora patogen busuk buah kakao. Penelitian dilaksanakan di Laboratorium Nanoteknologi Balai Besar Pascapanen, Bogor dan Laboratorium Proteksi Tanaman Balai Penelitian Tanaman Industri dan Penyegar, Sukabumi, mulai bulan Januari sampai Desember 2015. Formula nanoemulsi minyak serai wangi dibuat secara difusi spontan dan inversi dengan menambahkan pengemulsi Tween 80. Penelitian menggunakan rancangan acak lengkap dengan 6 perlakuan dan 5 ulangan. Perlakuannya adalah formula nanoemulsi minyak serai wangi (F1, F2, F3, F4, F5) dan kontrol. Konsentrasi formula yang diuji adalah 0,50% pada percobaan in vitro dan 1,00% pada buah kakao. Peubah yang diamati adalah daya hambat formula, bioassay, konsentrasi, dan daya hambat pada buah kakao.  Hasil penelitian menunjukkan bahwa formula nanoemulsi minyak serai wangi dapat menghambat pertumbuhan P. palmivora dengan daya hambat 23,11%–77,78% dibandingkan dengan kontrol. Formula terbaik adalah F5 dengan daya hambat 77,78% in vitro dan 31,60% pada buah kakao. Aktivitas nanoemulsi minyak serai wangi memengaruhi laju pertumbuhan jamur, bobot segar dan kering jamur. Untuk aplikasinya pada buah kakao perlu menaikkan konsentrasi agar keefektifannya lebih meningkat.
Keywords
Antifungal; citronella; formula; geraniol; nanotechnology, , Anti jamur; formula; geraniol; nanoteknologi; sitronella,
Citation