Pengaruh Stres Kekeringan Pada Fase Vegetatif Terhadap Kandungan Prolin, Gula Total Terlarut Pada Beberapa Genotip Kedelai (Glycine Max (L.) Merr.) Wahyu Widoretno, Linda Winarsih Fakultas MIPA, Universitas Brawijaya Abstrak Penelitian ini bertujuan untuk: (1) mengetahui pengaruh cekaman kekeringan yang disimulasi polietilena glikol (PEG) pada pertumbuhan vegetatif, kandungan prolin dan gula total terlarut beberapa genotipe kedelai, (2) mengetahui tingkat toleransi kekeringan beberapa genotipe kedelai berdasarkan respon pertumbuhan vegetatif pada kondisi kekeringan, (3) menentukan indikator fisiologis untuk toleransi kekeringan pada kedelai. Evaluasi pengaruh cekaman kekeringan dilakukan denganmenambahkan PEG padamedia tanamselama 2 minggu dengan konsentrasi 5%, 10%, 15%dan 20%, yang setara dengan -0,03, -0,19, -0,41 dan -0,67MPa. Rancangan percobaan yang digunakan adalah rancangan acak kelompok faktorial dengan dua faktor, yaitu genotipe kedelai dan konsentrasi PEG. Evaluasi karakter fisiologis dilakukan dengan analisis prolin dan gula total terlarut pada daun kedelai dari genotipe toleran, medium dan peka cekaman kekeringan. Cekaman kekeringan dapat menghambat pertambahan tinggi tanaman, jumlah daun, luas daun, panjang internodus, dan menurunkan biomassa akar dan tajuk. Semakin besar dan lama cekaman kekeringan, semakin tinggi penghambatan pada pertumbuhan vegetatif. Besarnya penghambatan pertumbuhan vegetatif bervariasi diantara genotipe kedelai yang diujikan. Penurunan potensial airmampumeningkatkan akumulasi prolin dan gula total terlarut pada daun 5 genotipe kedelai yang diuji dengan peningkatan yang bervariasi. Akumulasi prolin dapat digunakan sebagai indikator toleransi kekeringan. Varietas toleranmengalami peningkatan akumulasi prolin lebih tinggi dengan pola yang teratur, dibandingkan dengan varietas peka. Sedangkan akumulasi gula total terlarut tidak dapat digunakan sebagai indikator tingkat toleransi kekeringan, karena akumulasinya pada varietas toleran dan peka tidakmenunjukkan perbedaan. Kata kunci: gula total terlarut, kedelai, polietilena glikol (PEG), prolin
The Effects of Drought Stress at Vegetative Phase on Growth, Proline and Soluble Total Sugar Content of Some Genotype Soybean (Glycine max (L.)Merr.) Abstract The effects of drought stress at vegetative phase on growth, proline and soluble total sugar content of some genotype soybean (glycine max (l.) merr.). The objectives of this experiment were (1) to evaluate the influence of drought stress simulated by PEG on vegetative growth, content of proline and soluble total sugar of soybean genotypes, (2) to determine the physiological indicator for drought tolerance on soybean. The effect of drought stresswere evaluated by addition of 5%, 10%, 15%and 20%PEGon medium which eqivalen -0,03, -0,19, -0,41 and -0,67MPa. The experiment were carried out in a factorial randomized complete block design (RCBD) with 2 factors namely, soybean genotypes and PEG concentration with LSD continous test (á0.05). The physiological characters were evaluated by analyzing proline and soluble total sugar on soybean’s leave of tolerant, medium and sensitive genotypes to drought stress. Drought stress in media inhibited vegetative growth of soybean. The inhibition of vegetative growth increased with increasing of drought stress. The inhibition level of vegetative growth was varying among soybean genotypes. Drought stress on soybean increased proline and soluble total sugar. The higher drought stress, the higher accumulation of proline and soluble total sugar. Increasing the content of proline and soluble total sugar were varying among tested soybean genotypes. Accumulation of proline could be used as an indicator for dought stress tolerance of soybean. The accumulation of proline on tolerant genotypes was higher than sensitive ones and had regular pattern. While the accumulation of soluble total sugar of soybean under drought stress condition could not be used as an indicator for dought stress tolerance of soybean. Keyword: polyethylena glycol (PEG), proline, soluble total sugar, soybean
DAFTAR PUSTAKA
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