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: Efisiensi Penggunaan Nitrogen Pada Padi (Oryza sativa L.)
Abstrak: Nitrogen fertilizer in the form of urea has become a staple for farmers, especially in Indonesia. Consequently, applying such large quantities of urea cannot be avoided. The understanding of nutrient-use efficiency on paddy-field is needed to increase plant productivity and reduce environmental pollution because of the utilization of luxury urea fertilizer. The objective of this research was to quantify the nitrogen-use efficiency (NUE) on paddy-field. This study was conducted in field and green house. The experiments were carried out in the experimental field at the Indonesian Center For Rice Research (ICRR), Subang-West Java and farmer’s field at Bogor– West Java. The N fertilizer applied in ICRR and farmer field were 225 and 612.25 kg urea/ha, established in experimental plots of about 25 m2. The N fertilizer applied in the green house experiment were 200, 300, 400, 500 and 600 kg urea/ha, respectivelly. The result showed that the NUE and N resorption were higher in ICRR than that of in farmer’s field. The green house experiment showed that the NUE and N resorption were higher under 500 kg urea/ha than other treatments. The plant growth, plant biomass, grain yield, NUET, NUEES, ANUE, PNUE dan N resorption were declined with the high availability in nitrogen-pool and increasing in large quantities at certain doses of N 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