Judul: Nitrogen transformation in flooded soil: application of rice straw and urea and its relation with nitrogen uptake and rice plant growth
Abstrak: The use of organic materials aimed at reducing the dependence on inputs such as chemical fertilizers can contribute to sustainability and improving the low N fertilizer efficiency of rice plants in paddy soils. Therefore, better understanding of N transformation in flooded soils, particularly the microbial transformation of N-organic amendments to plant-available N and gaseous N forms is needed: (1) for most efficient use of soil and organic materials N by rice plant , (2) for determining the potential of denitrification and (3) for aiding in the selection of N management practices for sustainable agriculture.
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Judul: Peran Azotobacter-like dan Azospirillum-like untuk Mengurangi Dosis Pupuk Nitrogen Anorganik pada Padi Sawah
Abstrak: Increasing rice productivity must be achieved continously to meet government and national target production. One of efforts to increase rice productivity is by N fertilization. Nitrogen availability in the soil is one of limiting factors to support rice growing and productivity. Nitrogen-fixing bacteria have ability to utilize atmosphere nitrogen become available in the soil. The use of nitrogen-fixing bacteria could be potential to reduce application of nitrogen fertilizer. The aims of the research were (1) to evaluate the ability of some nitrogen-fixing bacteria isolated from lowland rice and bio-fertilizers to fix atmosphere nitrogen, (2) to determine the effect of nitrogen-fixing bacteria in reducing inorganic N fertilizer on lowland rice. The research consisted of two experiments. The first experiment was a laboratory experiment, to isolate and select isolates that having a high capability to fix nitrogen. The research was conducted in September 2011-March 2012, at the Soil Biotechnology Laboratory, Department of Soil Science and Land Resources, IPB. Source of isolates were commercial bio-fertilizers (three types of liquid and one type of solid), and soil from lowland rice field at Sawah Baru Experimental Station. Medium used for growing of microbia i.e. nitrogen free mannitol (NFM), nitrogen free bromthymol blue (NFB), and nutrient agar (NA). Based on the results, two isolates have been selected (one Azotobacter-like bacteria and one Azospirillum-like bacteria, i.e At523 and Ap533, both have the highest solubility of ammonium, not antagonistic, and the ability to grow faster) and used for field experiment. The second experiment was a field experiment, to test the effect of nitrogen-fixing bacteria on lowland rice. The research was conducted in April-August 2012 at the plastic house of Babakan Sawah Baru Experimental Station, IPB. The experiment was arranged in randomized block design (RBD) with two factors, namely nitrogen fertilizer and type of bacteria. The rates of N fertilizer (urea) factor, i.e. 0, 50, 75 and 100 kg N ha-1. The types of bacteria factor, i.e. without bacteria, Azotobacter-like, Azospirillum-like, and consortium. Data were analyzed using analysis of variance and followed by Duncan's Multiple Range Test (DMRT) with standard error 5%. The results of the laboratorium experiment showed that all isolates of bacteria performed no significant differences on N fixing capability. Field research showed that consortium of Azotobacter-like and Azospirillum-like applied with 75% of inorganic N fertilizer from recommended dosage the highest agronomic effectiveness (117.01%) and yield increase up to 8.59%. According to this result, application of consortium bacteria could reduce 25% recommended dosage of N inorganic fertilizer.
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Judul: Penentuan jenis kelamin merpati kipas (columba livia) berdasarkan kromosom, hormon, ornamen bulu, tingkah laku seksual dan nilai hematologis
Abstrak: Pada penelitian ini diujicobakan penentunan jenis kelamin berdasarkan analisis kromosom, penentuan kadar hormon estrogen, pengukuran panjang barbula bulu, pengamatan tingkah laku seksual dan penentuan nilai hematologis terhadap 20 ekor burung merpati kipas, yang terdiri dari 10 ekor dewasa dan 10 ekor lepas sapih. Dengan kombinasi 0.5 ml darah utuh, 300 μl phythohemaglutinin, 1 ml fetal calf serum dan 5 ml media kultur RPMI 1640, diperoleh lebih dari 10 kumpulan me tafase kromosom dalam satu preparat. Analisis kromosom dengan teknik kultur darah hanya 0.5 ml ternyata dapat membedakan jenis kelamin merpati kipas dewasa maupun lepas sapih. Jumlah kromsom diperoleh 40 pasang dan tipe pasangan kromosom seksnya adalah metasentrik. Hasil penentuan kadar hormon estrogen serum darah menunjukkan bahwa pada merpati kipas betina dewasa kadar estradiol serumn ya 6.529 ± 2.575 p g/ml lebih tinggi (P<0.01) dari pada yang jantan dewasa, 2.011 ± 0.400 pg/ml. Sedangkan untuk merpati kipas betina lepas sapih, 3.007 ± 1.201 pg/ml, tidak berbeda nyata (P>0.01) dengan merpati lepas sapih jantan 1.678 ± 0.190 pg/ml. Pengukuran panjang barbula bulu merpati kipas dewasa jantan didapatkan panjang barbula sayap 346.18 ± 5.15 μm, ekor 388.9 3 ± 39.82 μm, dan badan 371.45 ± 28.80 μm lebih panjang (P<0.01) dari pada panjang barbula bulu sayap, ekor, dan badan burung merpati kipas betina, masing-masing adalah 303.81 ± 6.94 μm, 292.03 ± 26.50 μm, 285.76 ± 40.09 μm, tetapi untuk panjang barbula bulu sayap, ekor dan badan pada burung merpati kipas lepas sapih tidak berbeda (P>0.01) antara jantan dan betina. ...
Keyword: Columba livia