Growth and Yield Responses of NSIC Rc11 and Inipot-Ibon to Different Nitrogen Rates under Upland Condition

Abstract

Two consecutive upland rice wet season croppings (2012-2013) were conducted in Lipa clay loam soil at Los Baños, Laguna, Philippines. This was done to determine which among NSIC Rc11 (modern variety) and Inipot-Ibon (traditional variety) applied with six fertilizer rates [kg/ha of nitrogen (N), phosphorus (P) and potassium (K)] with increasing N levels: control (zero fertilizer), 0-0-30, 20-30-30, 40-30-30, 60-30-30, and 80-30-30, will improve plant growth, yield, and profit. NSIC Rc11 was more productive with comparative average grain yields of 2.42-4.70 t/ha compared to Inipot-Ibon with only 1.40-2.20 t/ha during the two cropping seasons. This was due to the higher harvest index, tiller, panicle production, and return on investment (ROI) of NSIC Rc11 compared to Inipot-Ibon. Application of 20-80 kg/ha N plus 30 kg of both P and K significantly increased the grain and straw yields of NSIC Rc11 but not Inipot-Ibon having no significant response to fertilizer application. Highest ROI, though, was observed from the application of 60-30-30 kg/ha NPK to NSIC Rc11. The economic benefit from producing upland rice was very low due to the high cost of production from land preparation and maintenance costs (i.e. herbicides and pesticides application, contract labor for manual weeding). Keywords - itrogen rate, upland rice, yield performance, return on investment, experimental design, Philippines