In vitro propagation and micro bulb induction of shallot

Abstract

Shallot growers use harvested bulbs as propagules for the next planting. The use of the bulbs may cause degenerative diseases. Therefore, propagation system of shallot must be sought. A series of experiments were conducted in the Department of Agronomy and Horticulture IPB and the University of Queensland from May 2007 to July 2011. The first objective in this experiment was to determine the effect of explant storage duration on in vitro shoot multiplication of shallot. The experimental results showed storage length affected the growth of culture. Twomonth stored bulbs gave the best results on the number of micro shoots, number of leaves and roots and less vitrification. Four-week-old shoots were the best used for micro-propagules in shallot micro bulb induction. The objective of the second experiment was to determine the effect of temperature on the formation of shallot micro bulbs. It was shown that room temperature influenced the number of micro bulb, bulb base diameter, the widest diameter, ratio of the widest diameter and the base diameter of shallot micro bulb (Dt / Dp), root length, shoot length, number of leaves, number of senescing leaf. Temperature of 30/27 °C was better than 20/17 oC in accelerating the process of micro-bulb formation and increased the size of shallot micro bulbs. The objective of the third experiment was to determine the effect of sucrose and paclobutrazol on micro bulb induction. No interaction between sucrose and paclobutrazol was shown. Sucrose affected plant height, number of senescing leaf, root number, root length, the weight of plantlets and micro bulb widest diameter. Sucrose concentration of 90 g L-1 was the best in inducing shallot micro bulbs. Paclobutrazol significantly affected plant height, number of senescing leaf, number and length of roots. Paclobutrazol at level 10 mg L-1 inhibited plant height, leaf number and root length. Paclobutrazol 0.1-10 mg L-1 shortened root length. Paclobutrazol at concentration of 1 and 10 mg L-1 produced an abnormal form of micro bulb. The objective of the fourth experiment was to determine the success of shallot shoot and micro bulb acclimatization. At this stage of acclimatization, micro bulbs could be successfully grown for 3 weeks after acclimatization. Micro bulb was better in acclimatization than rooted plantlet. Plants may be transplanted to the field at 2 weeks after acclimatization. It is concluded that bulb stored for two months was the best for shoot multiplication. Media MS+vit B5 and 90 g L-1 sucrose at 30 oC was the best for bulb induction. Paclobutrazol should not be used for bulb induction. Bulb was better acclimatized than planlet. The media for acclimatization was green leaf compost and husk charcoal.

Bawang merah merupakan salah satu komoditas sayuran penting di Indonesia. Masalah yang dihadapi petani bawang merah pada umumnya adalah ketersediaan bibit yang berkualitas. Petani pada umumya menggunakan bibit dari hasil pertanaman sebelumnya. Hal ini dapat mengakibatkan penyakit degeneratif yang akan menurunkan pertumbuhan dan produksi bawang merah di lapangan. Tujuan umum dari penelitian ini adalah mendapatkan metoda perbanyakan bibit bawang merah yang mendukung penyediaan bibit berkualitas dari laboratorium sampai lapangan. Salah satu faktor yang memengaruhi morfogenesis kultur adalah umur eksplan. Umbi lapis bawang merah untuk bibit mengalami penyimpanan pada suhu tinggi (30-45 oC) selama 2-4 bulan. Tunas in vitro yang sesuai akan dijadikan sebagai propagul untuk diinduksi menjadi umbi lapis mikro. Induksi umbi lapis mikro pada famili Alliaceae dipengaruhi suhu, sukrosa, giberelin, dan cahaya. Tujuan pertama dalam percobaan ini adalah untuk mengetahui pengaruh umur eksplan dalam perbanyakan tunas in vitro bawang merah. Percobaan menggunakan Rancangan Acak Lengkap yang disusun dalam faktor tunggal yaitu umur simpan. Umur simpan umbi lapis terdiri atas empat taraf yaitu 1, 2, 3 dan 4 bulan simpan. Eksplan yang ditanam dalam media perbanyakan adalah setengah bagian umbi lapis yang mengandung cakram umbi (basal plate) yang terdiri atas dua lapisan terdalam umbi lapis. Setiap perlakuan diulang sebanyak 16 kali, sehingga terdapat 64 satuan percobaan. Setiap unit percobaan terdiri atas satu botol kultur yang ditanam satu eksplan. Hasil percobaan menunjukkan umur simpan berpengaruh terhadap pertumbuhan kultur. Umur simpan umbi lapis dua bulan memberikan hasil terbaik terhadap peubah jumlah tunas mikro (3.6), jumlah daun, dan akar dan sedikit terdapat vitrifikasi. Tunas mikro yang berumur empat minggu di media perbanyakan terbaik dipergunakan untuk propagul dalam pengumbian mikro bawang merah.