Pengelolaan Terpadu Virus pada Kacang Panjang dengan Tanaman Penghalang, Cendawan Endofit, dan Ekstrak Tanaman

Abstract

Budi daya kacang panjang (Vigna unguiculata ssp. sesquipedalis) banyak menghadapi hambatan, salah satunya karena gangguan hama dan penyakit tanaman. Hama yang umumnya menyerang tanaman kacang panjang antara lain ulat daun (Lepidoptera: Pyralidae), kutudaun (Hemiptera: Aphididae), kepik hijau (Hemiptera: Pentatomidae) dan belalang (Orthoptera: Acrididae). Adapun penyakit virus yang menjadi masalah penting dalam budi daya kacang panjang, diantaranya Bean common mosaic virus, Bean yellow mosaic virus, Cowpea aphid-borne mosaic virus, dan daun kecil kacang panjang (Cowpea witches-broom virus). Upaya pengelolaan virus pada tanaman kacang panjang yang pernah dilakukan antara lain dengan penggunaan tanaman penghalang, kitosan, bakteri rizosfer, ekstrak tanaman, cendawan endofit dan nanopartikel. Cendawan endofit dan ekstrak daun kelor dilaporkan efektif mengendalikan virus mosaik kacang panjang dan virus belang kacang tanah di rumah kaca. Penelitian lebih lanjut untuk menguji keefektifannya dalam mengendalikan infeksi alami virus di lapangan perlu dilakukan. Penelitian ini bertujuan menguji keefektifan integrasi tanaman penghalang jagung, cendawan endofit Lecanicillium lecanii PTN10, ekstrak daun bugenvil dan ekstrak daun kelor dalam mengendalikan virus tular serangga pada kacang panjang di lapangan. Percobaan dilaksanakan dengan rancangan petak terbagi (split plot) acak kelompok dengan lima perlakuan dan tiga ulangan. Insektisida kimia sintetik digunakan sebagai pembanding. Perlakuan subplot dalam petak utama tanpa tanpa tanaman penghalang (M0) dan dikelilingi oleh jagung sebagai tanaman penghalang (M1). Perlakuan anak petak terdiri dari kontrol (B1), endofit L. lecanii PTN10 (B2), ekstrak daun kelor (B3), ekstrak daun bugenvil (B4), dan insektisida (B5). Perbanyakan isolat cendawan endofit dan ekstrak daun tanaman dibuat dengan perbandingan 1:10 (b/v). Isolat cendawan endofit diperbanyak pada media beras dalam kantong plastik, dibiakkan sampai memenuhi permukaan beras. Perlakuan terdiri dari perlakuan benih dan semprot daun dua minggu sekali. Peubah yang diamati adalah intensitas penyakit virus, populasi kutudaun setiap minggu dan identitas virus diakhir percobaan. Virus dideteksi dan identifikasi dengan Polymerase chain reaction (PCR)/Reverse transcription-polymerase chain reaction (RT-PCR) dan perunutan DNA. Hubungan antara populasi kutudaun, intensitas penyakit dan hasil panen dianalisis dengan analisis regresi linier sederhana. Berdasarkan hasil pengamatan hama dan penyakit utama yang ditemukan di pertanaman adalah kutudaun dan penyakit mosaik. Secara umum, intensitas penyakit dan populasi kutudaun di petak M1 lebih rendah dibandingkan pada petak M0. Intensitas penyakit dan populasi kutudaun pada perlakuan L. lecanii PTN 10 dan perlakuan insektisida tidak berbeda nyata. Keefektifan perlakuan subplot dalam menekan insidensi, keparahan dan populasi kutudaun pada plot M1 berkisar antara 37,4%-73,0%; 28,6%-59,6%; dan 27,3%-73,7%; sedangkan pada plot M0 masing-masing adalah 34,4%-71,9%; 20,9%-54,6%; dan 17,0%-54,0%. Hasil penelitian menunjukkan bahwa L. lecanii PTN10 terbukti sebagai cendawan endofit dan entomopatogen potensial yang mampu mengendalikan virus dan vektor kutudaun dengan keefektifan yang sebanding dengan insektisida. Produksi kacang panjang meningkat pada subplot perlakuan sebesar 19,0%–75,0% pada petak utama M1 dibandingkan dengan petak utama M0. Hasil analisis korelasi antara intensitas penyakit dan hasil panen tergolong kuat sampai sangat kuat berkisar (R2 berkisar 0,775–1,00). Makin tinggi populasi kutudaun, maka makin tinggi intensitas penyakit dengan nilai R2 berkisar 0,683-1,00 (populasi kutudaun); 0,755–1,00 (insidensi penyakit); dan 0,922–1,00 (keparahan penyakit) tergantung pada perlakuan. Korelasi antara intensitas penyakit dan bobot panen kacang panjang tergolong kuat-sangat kuat R2 = 0,7717 dan R2 = 0,838. Hal ini menunjukkan bahwa perlakuan yang diterapkan berkorelasi kuat terhadap insidensi dan keparahan penyakit dengan hasil bobot panen (produksi). Integrasi tanaman penghalang jagung dengan L. lecanii PTN 10 dan ekstrak tanaman terbukti dapat meningkatkan keefektifan dalam pengelolaan virus tular kutudaun khususnya yang non-persisten yang menginfeksi kacang panjang di lapangan. PCR/RT-PCR dan perunutan DNA berhasil mengidentifikasi keberadaan beberapa virus tular kutudaun yaitu Bean common mosaic virus (BCMV), Cucumber mosaic virus (CMV), Cowpea polerovirus 2 (CpPV2) and tular kutukebul Mungbean yellow mosaic India virus (MYMIV). Analisis similaritas nukleotida menunjukkan bahwa isolat BCMV, CMV, MYMIV, dan CpPV2, berturut-turut berkisar 87% - 99%; 97% - 99%; 100%, dan 99% terhadap isolat virus yang sama dari negara lain. Analisis pohon filogenik menunjukkan bahwa virus yang teridentifikasi dari pertanaman di Nganjuk berada dalam satu kluster dan terpisah dengan kelompok isolat dari negara lain. Keberadaan CpPV2 merupakan laporan pertama menginfeksi tanaman kacang panjang di Kabupaten Nganjuk, Jawa Timur.

Yard long bean (Vigna unguiculata ssp. sesquipedalis) cultivation faces many production challenges, including pests and diseases. Pests that commonly attack long bean plants include caterpillars (Pyralidae), aphids (Aphididae), green stink bug (Pentatomidae), and grasshoppers (Acrididae). Viral diseases are a significant problem in long bean cultivation, including Bean common mosaic virus, Bean yellow mosaic virus, Cowpea aphid-borne mosaic virus, and Cowpea witches-broom virus. Efforts to manage viruses in yard long bean plants that have been implemented include the use of barrier plants, chitosan, rhizobacteria, plant extracts, endophytic fungi, and nanoparticles. Endophytic fungi and moringa leaf extract have been reported to be effective in controlling long bean mosaic virus and peanut mottle virus in greenhouses. However, their effectiveness in controlling natural viral infections in the field requires further research. This study aims to test the effectiveness of integrated methods of corn barrier plants with the endophytic fungus L. lecanii PTN10, bougainvillea leaf extract and moringa leaf extract in controlling insect-borne viruses in yard long beans in the field. The experiment was designed with a split plot randomized block design with five treatments and three replications. Insecticides were used as a comparator. Subplot treatments within the main plot were without barrier (M0) and surrounded by maize as a barrier plant (M1). Subplot treatments consisted of control (B1), endophytic entomopathogen L. lecanii PTN10 (B2), moringa leaf extract (B3), bougainvillea leaf extract (B4), and insecticide (B5) as comparison. Endophytic fungal isolates and plant leaf extracts were propagated at a ratio of 1:10 (w/v). Endophytic fungal isolates were propagated on rice media in plastic bag, cultured until they covered the surface of the rice. Treatments consisted of seed treatment and two weekly foliar spraying. The parameters observed were the intensity of the viral disease, the weekly insect population, and the identity of the virus at the end of the experiment. Viruses were detected and identified by Polymerase chain reaction (PCR)/Reverse Transcription polymerase chain reaction (RT-PCR) and DNA sequencing. The relationship between insect population, disease intensity and crop yield was analyzed using simple linear regression analysis. Based on the observation results, the main pests found in the field trial were aphids and mosaic disease. In general, the disease intensity and aphid population in plot M1 were lower than in plot M0. The disease intensity and aphid population in sub plot treated with L. lecanii PTN 10 and insecticide did not differ significantly. The effectiveness of subplot treatments in suppressing the incidence, severity, and population of aphids in plot M1 ranged from 37,4%-73,0%; 28,6%-59,6%; and 27,3%-73,7%; while in plot M0 it was 34,4%-71,9%; 20,9%-54,6%; and 17,0%-54,0%, respectively. The results of the study indicate that L. lecanii PTN10 is proven to be a potential endophytic and entomopathogenic fungus capable of controlling viruses and aphid vectors with effectiveness comparable to insecticides. Yard long bean production increased in the treatment subplots by 19.0%–75.0% in the main plot M1 compared to the main plot M0. The correlation analysis between disease intensity and yield were classified as strong to very strong (R2 ranged from 0,775 to 1,00). The higher the aphid population, the higher the disease intensity with R2 values ranging from 0,683 to 1,00 (aphid population); 0,755 to 1,00 (disease incidence); and 0,922 to 1,00 (disease severity) depending on the treatment. The correlation between disease intensity and long bean harvest weight was classified as strong to very strong R2 = 0,7717 and R2 = 0,838. This indicates that the applied treatment has a strong correlation between disease incidence and severity with harvest weight (production). The integration of corn barrier plants with L. lecanii PTN 10 and plant extracts has been proven to increase the effectiveness in managing aphid-borne viruses, especially non-persistent ones that infect yard long beans in the field. PCR/RT-PCR and DNA sequencing successfully identified several aphid-borne viruses, namely Bean common mosaic virus (BCMV), Cucumber mosaic virus (CMV), Cowpea polerovirus 2 (CpPV2), and whitefly-borne virus, Mungbean yellow mosaic India virus (MYMIV). Nucleotide similarity analysis showed that isolates of BCMV, CMV, MYMIV, and CpPV2 had 87% - 99%; 97% - 99%; 100%, and 99% to isolates from other countries, respectively. Phylogenetic tree analysis showed that the viruses identified from field trial in Nganjuk were in a single cluster and separate from other countries. The presence of CpPV2 was the first report of infection on yard long bean plants in Nganjuk Regency, East Java.