MORPHOGENETIC VARIATION OF SHALLOT (Allium cepa L. Aggregatum group) AND RESPONSE TO Fusariun oxysporum f.sp. cepae UNDER BIOFERFTILIZER APPLICATION

ALFU LAILA, Dr. Ir. Endang Sulistyaningsih M.Sc.

2013 | Tesis | S2 Agronomi

Terdapat banyak kultivar bawang merah yang ditanam di Pulau Jawa dengan sifat morfologi dan hasil yang beragam. Keragaman tersebut mengindikasikan kemungkinan adanya keragaman genetik yang juga menentukan sifat ketahanan terhadap penyakit. Salah satu penyakit penting pada tanaman bawang merah yang dapat mengakibatkan kehilangan hasil hingga 90% adalah penyakit moler yang disebabkan oleh Fusarium oxysporum f. sp. Cepae (Foc). Pada penelitian ini, enam belas kultivar bawang merah dikoleksi dan dipelajari keragaman genetik berdasarkan Random Amplified Polymorphism DNA (RAPD) dan karakteristik morfologi. Penelitian dilakukan dari bulan Desember hingga Febuari 2012 di Fakultas Pertanian, Universitas Gadjah Mada, Yogyakarta. Empat kultivar bawang merah yakni Tiron, Crok, Trisula dan Kuning dipilih untuk dipelajari tanggapan bawang merah terhadap inokulasi Foc dan aplikasi pupuk hayati. Percobaan lapangan dilakukan dari bulan Juni hingga Agustus 2012 di Kebun Percobaan Pendidikan, Penelitian dan Pengembangan Pertanian UGM in Kalitirto, Sleman, Yogyakarta. Percobaan penelitian menggunakan rancangan split plot 4 x 4 diulang tiga kali. Petak utama terdiri dari empat perlakuan kondisi penanaman bawang merah yakni ditanam pada kondisi yang telah diinokulasi Foc, aplikasi pupuk hayati pada kondisi yang telah diinokulasi Foc, aplikasi pupuk hayati tanpa inokulasi Foc, dan tanpa perlakuan. Anak petak terdiri dari empat kultivar. Data dianalisis menggunakan analisis keragaman. Berdasarkan analisis RAPD, dihasilkan bahwa koefisien kemiripan enam belas bawang merah berkisar dari 0,86 hingga 0,66. koefisien kemiripan menghasilkan dendogram molekular yang terbagi menjadi dua kelompok. Berdasarkan analisis morfologi, terdapat keragaman terhadap seluruh parameter yang diuji. Hasil dendogram morfologi menunjukkan bahwa keenam belas kultivar terbagi dalam empat kelompok. Kejadian penyakit moler karena terbawa oleh bibit menunjukkan 6.94%. Aplikasi pupuk hayati tidak mampu menurunkan secara nyata kejadian penyakit tersebut tapi dapat meningkatkan secara nyata jumlah umbi tiap tanaman pada kultivar Crok dan Kuning. Kejadian penyakit moler dengan persentase 43.75% pada perlakuan inokulasi Foc secara nyata menurunkan tinggi tanaman, jumlah umbi per tanaman, diameter umbi, panjang umbi dan hasil dari 1.05 kg/m2 hingga 0.63 kg/m2. Aplikasi pupuk hayati pada kondisi yang telah diinokulasi Foc secara nyata tidak dapat menurunkan kejadian penyakit moler dan meningkatkan hasil. Kultivar Trisula, Crok dan Tiron menunjukkan kejadian penyakit moler dan hasil yang tidak berbeda nyata dengan kultivar Kuning yang telah diketahui sebelumnya sebagai kultivar yang rentan terhadap Foc.

There are many shallot cultivars cultivated in Java with varying greatly morphological traits and yield. Morphological and yield variation indicate that there are genetic variation and varying in resistance to pest and disease. One of major disease that cause yield losses of shallot is Fusarium Basal Rot (FBR) caused by Fusarium oxysporum f. sp. cepae (Foc). The pathogen could cause yield losses of shallot in field up to 90%. The number of sixteen shallot cultivars were collected and studied for determining polymorphisms of nuclear based on Random Amplified Polymorphism DNA (RAPD) and the morphological traits. Potted research was conducted at greenhouse from December to February 2012, in Department of Agriculture, Universitas Gadjah Mada (UGM), Yogyakarta. Four shallot cultivars were selected for study the response to Foc under biofertilizer application. They were Kuning, Trisula, Tiron, and Crok cultivars. The field experiment was carried out from June to August 2012 at the Agricultural Training, Research and Development Station (ATRD/KP4) in Kalitirto, Sleman, Yogyakarta. The research was design split plot 4 x 4, with three replications. The plots consisted of shallot which cultivated in Foc inoculation, biofertilizer application, combination of Foc inoculation and biofertilizer application, and without any treatments. The subplot consisted of shallot cultivars. All data were statistically analyzed using the analysis of variance. Standard error was tested to determine the significant differences among treatment means. Similarity coefficient among shallot cultivars as revealed by UPGMA cluster analysis of RAPD markers generated to molecular dendogram. The similarity of genetic dendogram ranged from 0.85 to 0.66 and separated of cultivars into two groups. Based on morphological analysis, there were variations of all variable that tested. Mophological dendogram made possible to identify four group. Fusarium Basal Rot (FBR) incidence caused by seedborne was 6.94%. Biofertilizer application did not show decreasing significantly FBR incidence but it could increasing number of bulbs per plant on Crok and Kuning cultivars. FBR incidence with 43.75% caused by Foc inoculation was significantly decreasing plant height, sum of bulbs, diameter of bulbs, and length of bulbs. However, yield of shallot that cultivated on Foc inoculation showed decreasing significantly from 1.05 kg/m2 to 0.63 kg/m2. FBR incidence and increase the yield of shallot. FBR incidence and yield of Trisula, Crok and Tiron cultivars which cultivated on inoculated by Foc and under biofertilizer application did not show significantly difference compared to Kuning cultivar as susceptible to Foc.

Kata Kunci : cultivar, shallot, RAPD, Fusarium oxysporum f. sp. cepae (Foc), biofertilizer