Penetapan penambatan N 2 Rhizobacterium secara kuantitatif dengan teknik isotop 15 N Quantitative assessment of N 2 fixing Rhizobacterium using isotope 15 N technique

Ability to quantify the amounts of N 2 fixed in agri-cultural land is critical to manage the N cycle for optimalfood and plantation crop production. Isotope and relatednuclear technique such as 15 N isotope dilution technique hasplayed a significant role in nutrient management analysis forquantification of biological N 2 fixation. The largest pool of Nin the environment is atmospheric N 2 and it has a constantnatural abundance of 0.3663 % atom15 N. 15 N is a stableisotope of N and used as a unique tracer to evaluate thepotential of N 2 fixing bacteria, especially symbiotic and non-symbiotic Rhizobacterium. A field experiment has beeninitiated at IBRIEC to assess the N 2 fixing capacity ofrhizobacterium isolated from sandy textured soil at CentralKalimantan and evaluate the potential of bacteria N 2 fixingon corn (Zea mays). Field experiment has been conducted atCiomas Research Station, IBRIEC-Bogor for four months.The field experiment has been organized according to themethod of Randomized Complete Blocks Design with sixtreatments and three replicates. The results of this studysuggested that the method was reliable for estimation of %Ndfa as well as quantitative analysis of the amount of N fixedfrom the atmosphare. The proportion of N 2 uptake derivedfrom the atmophere was estimated as 32% of the whole plantbasis which was equivalent to approximately 4.8 kg N/ha.The inoculation of Rhizobacterium increased dry matter ofcorn leaves, roots, and grains significantly.AbstrakKemampuan penetapan jumlah N 2 yang dapat ditambatpada lahan pertanian merupakan suatu hal yang penting untukmengatur siklus N sebagai upaya mencapai tingkat produk-tivitas yang optimal di tanaman pangan dan perkebunan.Teknik isotop atau yang berhubungan dengan teknologinuklir seperti isotop 15 N memiliki peran signifikan di dalammanagemen kebun berbasis nutrisi untuk mengkuantifikasipenambatan N 2 secara biologi. Cadangan N terbesar di dalamlingkungan adalah N 2 atmosfer. Cadangan ini memilikikelimpahan alami yang stabil pada 0,3663 % atom 15 N. 15 Nmerupakan isotop yang stabil dan digunakan sebagai pelacakyang bersifat spesifik untuk mengevaluasi bakteri penambatN 2 potensial, khususnya bakteri di daerah perakaran, baikyang bersifat simbiotik ataupun non simbiotik. Penelitianterkait dengan uraian di atas telah dilakukan di BalaiPenelitian Bioteknologi Perkebunan Indonesia (BPBPI) dengan tujuan untuk menetapkan kemampuan menambatnitrogen dari Rhizobacterium yang diisolasi dari tanahtekstur berpasir asal Kalimantan Tengah serta mengevaluasipotensi bakteri dalam menambat N 2 pada tanaman jagung(Zea mays). Percobaan lapang dilakukan di Kebun PercobaanCiomas, BPBPI selama empat bulan. Kegiatan di lapangdidesain dalam Rancangan Acak Kelompok dengan enamperlakuan dan tiga ulangan. Hasil penelitian menunjukkanbahwa metode isotop 15 N dapat diaplikasikan untuk mem-perkirakan persentase N 2 yang ditambat dari atmosfer (Ndfa).Proporsi N yang diambil dari atmosfer diperkirakan sebesar32% dari seluruh bagian tanaman jagung yang setara dengan4,8 kg N/ha. Perlakuan inokulasi dengan Rhizobacteriummeningkatkan bobot kering daun, akar, dan pipilan jagungsecara signifikan.

Penetapan penambatan N 2 Rhizobacterium secara kuantitatif dengan teknik isotop 15 N Quantitative assessment of N 2 fixing Rhizobacterium using isotope 15 N technique

Ability to quantify the amounts of N 2 fixed in agri-cultural land is critical to manage the N cycle for optimalfood and plantation crop production. Isotope and relatednuclear technique such as 15 N isotope dilution technique hasplayed a significant role in nutrient management analysis forquantification of biological N 2 fixation. The largest pool of Nin the environment is atmospheric N 2 and it has a constantnatural abundance of 0.3663 % atom15 N. 15 N is a stableisotope of N and used as a unique tracer to evaluate thepotential of N 2 fixing bacteria, especially symbiotic and non-symbiotic Rhizobacterium. A field experiment has beeninitiated at IBRIEC to assess the N 2 fixing capacity ofrhizobacterium isolated from sandy textured soil at CentralKalimantan and evaluate the potential of bacteria N 2 fixingon corn (Zea mays). Field experiment has been conducted atCiomas Research Station, IBRIEC-Bogor for four months.The field experiment has been organized according to themethod of Randomized Complete Blocks Design with sixtreatments and three replicates. The results of this studysuggested that the method was reliable for estimation of %Ndfa as well as quantitative analysis of the amount of N fixedfrom the atmosphare. The proportion of N 2 uptake derivedfrom the atmophere was estimated as 32% of the whole plantbasis which was equivalent to approximately 4.8 kg N/ha.The inoculation of Rhizobacterium increased dry matter ofcorn leaves, roots, and grains significantly.AbstrakKemampuan penetapan jumlah N 2 yang dapat ditambatpada lahan pertanian merupakan suatu hal yang penting untukmengatur siklus N sebagai upaya mencapai tingkat produk-tivitas yang optimal di tanaman pangan dan perkebunan.Teknik isotop atau yang berhubungan dengan teknologinuklir seperti isotop 15 N memiliki peran signifikan di dalammanagemen kebun berbasis nutrisi untuk mengkuantifikasipenambatan N 2 secara biologi. Cadangan N terbesar di dalamlingkungan adalah N 2 atmosfer. Cadangan ini memilikikelimpahan alami yang stabil pada 0,3663 % atom 15 N. 15 Nmerupakan isotop yang stabil dan digunakan sebagai pelacakyang bersifat spesifik untuk mengevaluasi bakteri penambatN 2 potensial, khususnya bakteri di daerah perakaran, baikyang bersifat simbiotik ataupun non simbiotik. Penelitianterkait dengan uraian di atas telah dilakukan di BalaiPenelitian Bioteknologi Perkebunan Indonesia (BPBPI) dengan tujuan untuk menetapkan kemampuan menambatnitrogen dari Rhizobacterium yang diisolasi dari tanahtekstur berpasir asal Kalimantan Tengah serta mengevaluasipotensi bakteri dalam menambat N 2 pada tanaman jagung(Zea mays). Percobaan lapang dilakukan di Kebun PercobaanCiomas, BPBPI selama empat bulan. Kegiatan di lapangdidesain dalam Rancangan Acak Kelompok dengan enamperlakuan dan tiga ulangan. Hasil penelitian menunjukkanbahwa metode isotop 15 N dapat diaplikasikan untuk mem-perkirakan persentase N 2 yang ditambat dari atmosfer (Ndfa).Proporsi N yang diambil dari atmosfer diperkirakan sebesar32% dari seluruh bagian tanaman jagung yang setara dengan4,8 kg N/ha. Perlakuan inokulasi dengan Rhizobacteriummeningkatkan bobot kering daun, akar, dan pipilan jagungsecara signifikan.

Delayed inoculation of alfalfa with Sinorhizobium meliloti and Penicillium bilaiae

Knight, J. D. 2015. Delayed inoculation of alfalfa with Sinorhizobium meliloti and Penicillium bilaiae. Can. J. Plant Sci. 95: 205–211. The persistence of perennial forage legume crops relies on the establishment of an effective symbiotic relationship with the appropriate Rhizobium species and strain. Situations can arise where a forage legume crop fails to symbiotically fix N2. This study investigates if inoculation of alfalfa with a commercial Sinorhizobium meliloti inoculant 1 yr after seeding can induce biological N2 fixation at levels similar to those achieved when the inoculant is applied at seeding. Alfalfa (Medicago meliloti cv. Algonkwin) was grown at two sites in Saskatchewan and inoculated with S. meliloti or S. meliloti plus the P-solubilizing fungus Penicillium bilaiae. The inoculants were applied at seeding or applied 1 yr after seeding. Biological N2 fixation was measured in the fall of the delayed inoculation year as percentage of N derived from atmosphere (%Ndfa) using the 15N isotope dilution technique. Inoculation with S. meliloti increased %Ndfa at both sites relative to uninoculated and fertilized controls but had no effect on total N content or yield. Inoculating alfalfa the year after seeding increased %Ndfa relative to the controls at both sites, and at one of the sites %Ndfa in the delayed treatments was at the same levels measured in the year of seeding treatments.

Evaluation of the “Olson Equation”, an Isotope Dilution Method for Estimating Vitamin A Stores

Isotope dilution methods have been successfully used to estimate vitamin A status in human populations as well as to evaluate the impact of vitamin A interventions. The most commonly applied isotope dilution method is the retinol isotope dilution technique, which is based on the 1989 “Olson equation” for estimating total body vitamin A stores (sometimes equated to liver vitamin A) after an oral dose of labeled vitamin A. The equation relies on several factors related to absorption and retention of the dose, the equilibration of label in plasma vs. liver, and timing of a blood sample for measurement of labeled vitamin A. Here, the assumptions underlying these factors are discussed, and new results based on applying model-based compartmental analysis [specifically, the Simulation, Analysis and Modeling software (WinSAAM)] to data on retinol kinetics in humans are summarized. A simplification of the Olson equation, in which plasma tracer is measured 3 days after administration of the oral dose and several factors are eliminated, is presented. The potential usefulness of the retinol isotope dilution technique for setting vitamin A requirements and assessing vitamin A status in children, as well as the confounding effects of inflammation and likely variability in vitamin A absorption, are also discussed.