Uji kemampuan bakteri diazotrof asal perakaran bawang merah dalam mendukung pertumbuhan dan hasil tanaman bawang merah
Authors: Purwanto Purwanto , Yuniarti Ananda Rahmalia , Rokhminarsih Eny 
Published: August 2022

AbstrakBudidaya tanaman bawang merah saat ini dihadapkan pada masalah stagnasi produksi akibat aplikasi pupuk kimia secara berlebihan sehngga efisiensi pemupukan rendah. Teknologi ramah lingkungan dan efisien pupuk dengan aplikasi bioteknologi melalui aplikasi bakteri berguna seperti bakteri penambat nitrogen. Penelitian bertujuan untuk (1) mengetahui respons pertumbuhan dan hasil tanaman bawang merah terhadap bakteri diazotrof, (2) menetapkan isolat bakteri diazotrof yang paling baik untuk pertumbuhan dan hasil tanaman bawang merah. Percobaan dilaksanakan pada bulan Januari 2021 sampai April 2021. Percobaan dilaksanakan di Rumah Kassa serta  Laboratorium Agronomi dan Hortikultura Fakultas Pertanian, Universitas Jenderal Soedirman. Rancangan percobaan yang digunakan yaitu Rancangan Acak Kelompok Lengkap (RAKL) dengan perlakuan jenis isolat bakteri diazotrof terdiri dari 9 jenis isolate dan 1 kontrol yaitu I1 = LCR3, I2 = LAR5, I3 = LBR1, I4 = LAZ2, I5 = LAZ3, I6 = LCA1, I7 = LAR3, I8 = LAA5, dan I9 = LAA4. Masing-masing diulang 3 kali. Variabel yang diamati yaitu tinggi tanaman (cm), jumlah daun (helai), kehijauan daun (SPAD unit), panjang akar total (cm), volume akar (ml), bobot kering tajuk  (g), bobot kering akar (g), rasio akar:tajuk, jumlah umbi (biji), volume umbi (ml), bobot umbi segar (g), bobot umbi askip (g), indeks panen. Hasil percobaan menunjukkan bahwa aplikasi bakteri penambat N2 dapat meningkatkan pertumbuhan dan hasil tanaman bawang merah. Variabel yang berpengaruh nyata yaitu Pemberian isolat bakteri penambat nitrogen secara nyata berpengaruh terhadap jumlah daun, kehijauan daun, bobot tajuk kering, bobot akar kering, rasio akar/tajuk, jumlah umbi sebesar 70,72%, dan bobot umbi eskip sebesar 90,63% dibandingkan dengan kontrol. Perlakuan isolat LCR3 menghasilkan angka tertinggi pada variabel bobot umbi eskip.Kata Kunci: Bawang merah, bakteri diazotrof, nitrogen AbstractShallot (Allium ascalonicum L) cultivation is currently faced with the problem of production stagnation due to excessive application of chemical fertilizers so that fertilization efficiency is low. Eco-friendly and efficient fertilizer technology, in terms of biotechnology, such the application of useful bacteria, namely nitrogen fixing bacteria is promising solution. The research aimed to (1) determine the growth and yield response of shallots against diazotrophic bacteria, (2) determine and select the best diazotrophic bacterial isolates for the growth and yield of shallots. The experiment was conducted from January to April 2021 in Screenhouse and Laboratory of Agronomy and Horticulture, Faculty of Agriculture, Jenderal Soedirman University. The experimental design used was a Randomized Completely Block Design (RCBD). The treatment of diazotrophic bacterial isolates consisted of 9 isolates and 1 control, i.e., I1 = LCR3, I2 = LAR5, I3 = LBR1, I4 = LAZ2, I5 = LAZ3, I6 = LCA1, I7 = LAR3, I8 = LAA5, and I9 = LAA4. All of them replicated three times. Variables observed were plant height, number of leaves, leaf greenness, total root length, root volume, shoot dry weight, root dry weight, root shoot ratio, number of bulbs, bulb volume, fresh bulb weight, sun dried bulb weight, and harvest index. The results showed that application of diazotroph bacteria could increase the growth and yield of shallots. Application of diazotroph bacteria had a significant effect on number of leaves, leaf greenness, dry shoot weight, dry root weight, root shoot ratio, number of bulbs by 70.72%, and sun dried bulb weight by 90.63% compared to the control. Treatment LCR3 produced the highest number of sun dried bulb weight.Keywords: Shallot, diazotrophic bacteria, nitrogen