Malays. Appl. Biol. (2010) 39(2): 41-45
ISOLATION AND PLANT GROWTH-PROMOTING PROPERTIES OF RHIZOBACTERIAL DIAZOTROPHS FROM PEPPER VINE (Piper nigrum L.)
ZAKRY, F.A.A.1,3,*, HALIMI, M.S.1,2, ABDUL RAHIM, K.B.5, OSUMANU, H.A.3, WONG, S.K.4, FRANKLIN, R.K.3, STEPHEN, L.C.T.3 and MAKE, J.3
1Laboratory of Plantation Crops, Institute of Tropical Agriculture, 2Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor; 3Department of Crop Science, 4Department of Animal Science and Fisheries, Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia Bintulu Campus Sarawak, 97008 Bintulu, Sarawak; 5Agrotechnology and Biosciences Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor, Malaysia. E-mail:
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ABSTRACT
N2-fixing rhizobacteria from pepper rhizosphere were isolated and characterised for phosphate solubilisation, phytohormone auxin production and plant growth promotion. A total of 45 bacterial isolates with prolific growth were successfully isolated and screened for N2-fixing activity. Out of 45 rhizobacterial isolates, 14 were characterised as diazotrophic rhizobacteria, fixing N2 in the range of 0.07 to 0.24 ppm of culture filtrates. Two out of 14 isolates, namely UPMLH3 and UPMLH13, were able to solubilise phosphate with solubilisation efficiency at 286% and 563%, respectively. Six isolates were able to produced indole-3-acetic acid, ranging from 36.71 to 63.05 ?g mL-1. Using shallot plant as a test crop, isolate UPMLH1 can substantially increase most plant growth parameters (compared to the uninoculated control), such as viz root number (52%), shoot height (54%), root fresh weight (144%), shoot fresh weight (57%) and shoot dry weight (68%). Isolate UPMLH1 accumulated the highest N through N2-fixing activity (0.24 ppm), produced substantial amount of IAA (63.05 ?g mL-1) and stimulated plant growth (52 to 144% increase), thus, has a good potential to be developed as a plant growth- promoting rhizobacteria. Isolate UPMLH13 could also be considered as a potential phosphatic biofertilizer which could be incorporated with isolate UPMLH1 to establish a multifunctional biofertiliser for pepper vine together.
ABSTRAK
Rizobakteria mengikat-N2 dari rizosfera lada telah dipencil dan dicirikan untuk pelarutan fosfat, penghasilan fitohormon auksin dan penggalakan tumbesaran tumbuhan. Sejumlah 45 isolat bakteria yang cepat tumbuh telah berjaya dipencilkan dan dicirikan untuk aktiviti mengikat N2. Daripada 45 isolat rizobakteria, 14 dicirikan sebagai isolat rizobakteria diazotrof dan mengikat nitrogen dalam lingkungan 0.07 ke 0.24 ppm dari kultur filtrat. Daripada 14, dua isolat, iaitu UPMLH3 dan UPMLH13, boleh melarutkan fosfat dengan kecekapan pelarutan masing-masing pada 286% dan 563%. Enam isolat boleh menghasilkan asid indol-3-asetik, dalam lingkungan 36.71 ke 63.05 ?g mL-1. Menggunakan tumbuhan bawang kecil sebagai tanaman ujian, isolat UPMLH1 boleh meningkatkan kebanyakan parameter-parameter pertumbuhan berbanding kawalan tanpa inokulasi seperti bilangan akar (52%), tinggi pucuk (54%), berat basah akar (144%), berat basah pucuk (57%) dan berat kering pucuk (68%). Isolat UPMLH1 menambah nitrogen tertinggi menerusi aktiviti mengikat N2 (0.24 ppm), penghasilan IAA (63.05 ?g mL-1) dan merangsangkan pertumbuhan tumbuhan (peningkatan 52 ke 144%) mempunyai potensi yang menyakinkan untuk dibangunkan sebagai rizobakteria penggalak-tumbesaran tumbuhan. Isolat UPMLH13 juga boleh dipertimbangkan sebagai biobaja fosfatik dan mungkin juga dikombinasikan dengan isolat UPMLH1, dibangunkan bersama sebagai biobaja pelbagai fungsi untuk tanaman lada.
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