PENGARUH INOKULASI RHIZOBIUM TERHADAP PENYERAPAN Cu DAN PERTUMBUHAN KACANG TANAH ( Arachis hypogaea L.)

Abstract

This study was conducted to determine the effects of Cu on the growth of peanut plants (Arachis hypogaea L.) inoculated with rhizobium. Cu distribution in plant organs was also analyzed. This study was carried out using factorial completely randomized design with six replications for each treatment. The first factor was CuSO4 concentration, A0: CuSO4 0 mg/3 kg soil, A1: CuSO4 60 mg/3 kg soil, A2: CuSO4 90 mg/3 kg soil and A3: CuSO4 120 mg/3 kg soil). The second factor was legin inoculation B0: without legin inoculation, B1: legin inoculation of 10 g/kg seed, B2: legin inoculation of 20 g/kg seed. The measured parameters were Cu content in plant organs (stems, roots and leaves), Cu concentration in the seeds, the number of root nodules and plant growth. Collected data were statistically analyzed using analysis of variance (Anova) and further tested by DMRT (Duncan Multiple Range Test) at 95% level of confidence.The results showed that application of Cu combined with rhizobium gave impacts on plant growth parameters. In small amounts (60 mg CuSO4/3 kg of soil) could improve plant growth, but excess of CuSO 4 in soil decreased plant growth. Cu was distributed to all plant organs, including seeds. Legin inoculation significantly reduced growth inhibition and Cu absorbtion in excess Cu. High Cu concentration in the rhizosphere could reduced the number of nodule formed. The results also showed accumulation of Cu in the root. Keywords : PENDAHULUANPenelitian tentang akumulasi logam berat pada biji Vigna unguiculata L. dilakukan Ogbuehi et al., (2011) terdapat akumulasi nikel dan seng di biji tanaman pada tanah terkontaminasi. Hal ini akan membahayakan jika dikonsumsi manusia dapat menyebabkan mutasi dan kanker. Menurut Amaliyah (2011) biji bunga matahari dapat mengakumulasi Pb sebesar 25,42 %. Malan dan Farrant (1998) menyatakan pada tanaman kedelai yang terdapat pada media terkontaminasi dapat mengurangi biomassa dan produksi benih. Tingginya logam Cd dan Ni menyebabkan terdapatnya logam tersebut pada kotiledon. Selain itu akan menyebabkan penurunan biomassa biji. Hal ini terjadi karena adanya penurunan produksi lipid, protein dan karbohidrat.Kelebihan Cu di dalam tanah juga akan menginduksi penurunan fotosintesis dan fungsi rambut akar, sehingga menghasilkan pengurangan biomassa (Combroll et al., 2011). Pada kondisi stress oksidatif, tanaman akan