Pengaruh Naungan Plastik Transparan, Kerapatan Tanaman, dan Dosis N terhadap Produksi Umbi Bibit Asal Biji Bawang Merah

Abstract

ABSTRAK. Bawang merah dapat dibudidayakan menggunakan umbi bibit atau biji botani (TSS). Dari biji TSS dapat diproduksi umbi bibit mini (set), yang menghasilkan tanaman lebih sehat dan kualitas hasil umbi lebih baik dibandingkan dengan umbi bibit asal umbi (cara konvensional). Banyak faktor yang memengaruhi produksi umbi mini asal biji TSS, antara lain kerapatan tanaman, pemupukan N, dan naungan. Penelitian bertujuan mendapatkan naungan, kerapatan tanaman, dan dosis N yang sesuai untuk produksi umbi bibit asal biji bawang merah. Penelitian dilaksanakan di Kebun Percobaan Balai Penelitian Tanaman Sayuran Lembang (1.250 m dpl.) dengan jenis tanah Andisol, dari bulan Oktober 2005 sampai Februari 2006. Rancangan percobaan yang digunakan adalah acak kelompok faktorial dengan tiga ulangan dan tiga faktor perlakuan. Faktor pertama adalah naungan, terdiri atas tiga taraf yaitu naungan plastik transparan digunakan dari awal semai biji sampai panen umbi, naungan plastik transparan digunakan dari awal semai biji sampai tanaman berumur enam minggu, dan tanpa naungan. Faktor kedua adalah kerapatan tanaman, terdiri dari tiga taraf yaitu 4, 6, dan 8 g biji/m2. Faktor ketiga adalah dosis pupuk N, terdiri atas dua taraf yaitu 45 dan 90 kg N/ha. Hasil penelitian menunjukkan bahwa naungan dan kerapatan tanaman berpengaruh secara nyata terhadap pertumbuhan dan hasil umbi bawang merah asal biji, sedang pemberian 45 dan 90 kg N/ha tidak memberikan perbedaan pertumbuhan dan hasil umbi bawang merah yang nyata. Hasil bobot umbi kering eskip tertinggi sebesar 2,54 kg/m2 diperoleh dari penggunaan naungan plastik transparan sejak awal biji disemai sampai panen yang dikombinasikan dengan kerapatan tanaman 8 g biji/m2 dan dosis 45 kg N/ha. Hasil bobot umbi tersebut lebih dari 70% berukuran umbi konsumsi  (>5 g/umbi), sisanya berukuran umbi bibit (3-5 g/umbi). Umbi bibit mini (<2 g/umbi) tidak dihasilkan. Teknologi ini diharapkan dapat digunakan untuk meningkatkan hasil dan kualitas hasil umbi bibit bawang merah

ABSTRACT. Sumarni, N. and R. Rosliani. 2010. The Effect of Transparent Plastic Shelter, Plant Density, and N Dosages on Shallots Seed Production from True Shallots Seed (TSS). Shallots can be cultivated by using bulb seed or TSS. Planting materials from TSS could produce mini bulb seeds which finally gave healthier shallots plant with high quality of bulb yield than that of from bulbs (conventional method). Several factors affected the yield of mini bulb shallots seed, among other thing are plant density, N fertilization, and the application of transparent plastic shading. The objective of this experiment was to find out the effect of plastic shelter, plant density, and N dosage to produce shallot bulb seeds from TSS. The research was carried out at the Experimental Garden of Indonesian Vegetables Research Institute Lembang (1,250 m asl.) on Andisol type soil from October 2005 to February 2006. The treatments were set up in a factorial randomized block design with three replications. The treatments comprised of three factors. The first factor was application of transparent plastic shelter with three levels, viz. (1) transparent  plastic shelter from the beginning of seeds sowing (direct seeded) up to harvest the shallots seed, (2) transparent plastic shelter from the beginning of direct seeded up to six weeks, and (3) without shelter (control). The second factor was the plant density comprised of three levels, viz : 4, 6, and 8 g/m2 of TSS. The third factor was the dosages of N fertilizer with two levels, viz : 45 and 90 kg N/ha. The results showed that the application of transparent plastic shelter and plant density significantly affected the plant growth and shallots seed yield. Application of N fertilizer of 45 to 90 kg N/ha did not significantly affect plant growth  and shallots seed yield eventually. The highest yield of shallots seed, viz. 2.54 kg/m2 was gained from the application of transparent plastic shelter from the beginning of sowing untill harvest with plant density of 8 g/m2 of TSS and 45 kg N/ha, with more than 70% bulb size for consumption (>5 g/bulb), and the rest  17 to 20% bulb size for seed (3 to 5 g/bulb). No mini bulb shallots seed (<2 g/bulb) was produced. This technique was quite promising and potential for increasing yield and bulb quality of shallots seed.