SERAPAN FOSFOR DAN KUALITAS RUMPUT PAKAN POLIPLOID DAN DIPLOID YANG TOLERAN CEKAMAN KEMASAMAN TANAH PADA PEMUPUKAN FOSFOR (The Phosphorus uptake and Quality of Polyploid and Diploid Fodder Grass on Acidity Soil Stress.)

Abstract

The aim of this research was to measure response of polyploid and diploid fodder grass crop as well as among polyploid fodder grass crop which was tolerant against acidity soil towards phosphorus fertilization based on phosphorus uptake and quality. The research was carried out from January 2004 until June 2004 in Green House and The Forage Crop Laboratory of Department of Food Science and Nutrition, Faculty of Animal Agriculture Diponegoro University in Semarang. The research used Completely Randomized Design with split plot pattern. The main plot is kinds of grass and phosphorus fertilizer dosage is subplot, within three replications. Kinds of grass consist of R1 = Brachiaria brizantha poliploid, R2 = Brachiaria decumbens poliploid, R3 = Panicum muticum poliploid, R4 = Brachiaria brizantha diploid, R5 = Brachiaria decumbens diploid, R6 = Panicum muticum diploid. There are four levels of phosphorus fertilization, i.e. : 0 kg, 150 kg, 225 kg, 300 kg P205 per hectare. The observed parameters were : phosphorus uptake, eficiency of phosphorus use, the content of chlorophyll, nitrate reductase activity, crude protein, crude fibre, and dry matter production. The data obtained from these parameters was analysed through analyses of variance, and followed by Duncan test (5%). In order to measure the phosphorus fertilization response, then the data was further analyzed by using Orthogonal Polynomial test in order to get the regression equation. The research showed that phosphorus fertilization dosage and interactions between kinds of grass with phosphorus fertilization dosage did not affect to all parameter of this research (P > 0,05), except the content of crude fibre; whereas kinds of grass affect the content of chlorophyll, crude protein, crude fibre, and dry matter production. The conclusion of this research is : (1) There are no differences of response between polyploid and diploid fodder grass towards phosphorus fertilization based on phosphorus uptake, eficiency of phosphorus use, the content of chlorophyll, crude protein, nitrate reductase activity, dry matter production. (2) The response of Brachiaria brizantha polyploid grass is different with all fodder grass based on the content of crude fibre. (3) Polyploid fodder grass having high genetic potency based on research parameters are : 1. B. brizantha, 2. B. decumbens, 3. P. muticum, or 1. B. decumbens, 2. B. brizantha, 3. P. muticum. Based on responsibility towards phosphorus fertilization in order : 1. B. brizantha, 2. B. decumbens, 3. P. muticum, or 1. B. brizantha, 2. P. muticum, 3. B. decumbens. Penelitian ini bertujuan untuk mengetahui respon tanaman rumput pakan poliploid dan diploid, serta diantara berbagai tanaman rumput pakan poliploid yang toleran terhadap cekaman kemasaman tanah terhadap pemupukan fosfor berdasarkan serapan fosfor dan kualitas. Penelitian telah dilaksanakan di rumah kaca dan Laboratorium Ilmu Tanaman Makanan Ternak, Fakultas Peternakan Universitas Diponegoro, pada bulan Januari 2004 hingga Juni 2004. Rancangan yang digunakan dalam penelitian ini adalah rancangan acak lengkap berpola split plot, sebagai petak utama adalah rumput pakan dan anak petak dosis pupuk P, dengan tiga kali pengulangan. Rumput yang digunakan = Brachiaria brizantha poliploid, R2 = Brachiaria decumbens poliploid, R3 = Panic= muticum poliploid, R4 = Brachiaria brizantha diploid, R5 = Brachiaria decumbens diploid, R6 = Panicum muticum diploid. Pupuk SP dalam empat dosis yaitu : 0 kg, 150 kg, 225 kg, 300 kg P205/ha/tahun. Parameter yang diukur yaitu : serapan fosfor, efisiensi pemanfaatan fosfor, kadar klorofil, aktivitas nitrat reduktase, protein kasar, serat kasar, dan produksi bahan kering. Data yang diperoleh dianalisis dengan uji ragam dilanjutkan dengan uji Duncan taraf 5%. Untuk mengetahui respon pemupukan fosfor dilakukan uji lanjut dengan Uji Polynomial Ortogonal dengan persamaan regresinya. Berdasarkan uji ragam menunjukkan dosis pupuk SP, interaksi dosis pupuk SP dengan jenis rumput tidak berpengaruh terhadap semua parameter penelitian (P > 0,05), kecuali terhadap kandungan serat kasar. Sedangkan jenis rumput berpengaruh terhadap kadar klorofil, protein kasar, serat kasar, dan produlcsi bahan kering. Kesimpulan penelitian adalah : (1) Tidak terdapat perbedaan respois ruinput pakan poliploid maupun diploid terhadap pemupukan fosfor berdasarkan parameter serapan fosfor, efisiensi pemanfaatan fosfor, kadar klorofil, aktivitas nitrat reduktase, protein kasar, produksi bahan kering. (2) Berdasarkan kadar serat kasar, Brachiaria brizantha poliploid memberikan respon yang berbeda. (3) Rumput pakan poliploid yang memiliki potensi genetis tinggi berdasar parameter penelitian berturut-turut : 1. B. brizantha, 2. B. decumbens, 3. P. muticum atau 1. B. decumbens, 2. B. brizantha, 3. P. muticum. Berdasarkan responsibilitas terhadap pemupukan SP berturut-turut : 1. B. brizantha, 2. B. decumbens, 3. P. muticum, atau 1. B. brizantha, 2. P. muticum, 3. B. decumbens.