Nitrogen Fertilizer Use Efficiency of Irradiated Mutant Rice

Abstract

The carrying capacity of rice plants to meet national food demand is inseparable from effective and efficient cultivation techniques. The need of rice plants for fertilizer is a recurring problem, due to the farmers' tendency to apply fertilizer, especially urea, at the excessive doses. Balanced fertilizer practice is currently a trend encouraged by the government, because the lands that receive intensive chemical fertilization rate decreased in its fertility and health. It is indicated by the low soil acidity value (tends to be acidic to acidic) and the low soil organic carbon (SOC) content (<1%). This case happens in most areas of intensive rice cultivation in Indonesia. The principle of balanced fertilization is to provide a number of nutrients in accordance with the amount of plant needs. Determining the nutrients needed by plants can be done in several ways, including by knowing the efficiency level of plants in utilizing the nutrients that are given or added to the soil. The research objective was to determine the fertilizer dosage with the optimum efficiency level for lowland rice plants. The experiment was carried out in the rice fields of Muara Experimental Station, Bogor, using Batan's mutant rice variety and mutant line, and national rice variety as a comparison. Randomized Complete Block Design in factorial pattern was using in the experiment. As the first factor is rice variety, consisting of 3 levels factors: 1). Sidenuk mutant rice; 2). mutant line rice; and 3). Ciherang national rice variety. While the dose of urea as second factor consists of 4 levels: 1). no urea fertilizer; 2). urea at a dose of 100 kg N / ha; 3). urea at a dose of 200 kg N / ha; and 4). urea at a dose of 300 kg N / ha. Stable isotope techniques 15 N is used to determine the efficiency of nitrogen uptake by rice plants. The results showed that the highest nitrogen use efficiency of rice varieties owned by Sidenuk amounted to 22.76%; Ciherang variety was 22.30%; and the mutant lines were 17.19%. This efficiency was obtained from the application of urea fertilizer at a dose of 100 kg N / ha (Sidenuk and Ciherang) and 200 kg N / ha (mutant lines).