Critical Leaf Color Chart Level and N Determination for Rice Production in Fogera Plain

Abstract

Assessment of nitrogen status in standing crop and its application according to the crop need is a best approach to reduce the loss. Leaf Color Chart (LCC) is one of the best methods for monitoring leaf N status. Field experiment was conducted at Fogera plain for two years in 2019 and 2020 main cropping seasons to determine the critical LCC value of X-Jigna rice variety and the level of appropriate N rate to be applied at the critical LCC. The treatments included a factorial combination of four levels of LCC cv. (LCC cv. 1, 2, 3, and 4) with different rates of N application (20, 25, 30 and 35 kg ha^-1 at a time) along with two checks {(control (0 kg N ha^-1), and recommended N (276 kg N ha^-1 in two splits*1/3 at planting + 2/3 at maximum tillering)}. The statistical analysis indicated that dry biomass and grain yields were significantly affected by the interactions of the LCC values and the N rates. The LC4+35 kg N  ha^-1 treatment was found to give statistically equivalent grain and biomass yields compared to the recommended N rate (276 kg ha^-1) with the reduction of 101 kg (36.6%) N. The economic analysis indicated that highest Net Benefit (Birr 64,975.46/ha) with 652.155% Marginal Rate of Return was obtained at the LCC4 combined with 35 kg ha^-1 N. The application of nitrogen to rice at the rate of 35 kg ha^-1 N whenever the leaf color of the rice plant matching the value of LCC4 is recommended for rainfed lowland rice production in Fogera for X-Jigna variety.