Identification of Yield Limiting Nutrients in Rice (Oryza sativa L.) Through DRIS Indices

Abstract

The Diagnosis and Recommendation Integrated System (DRIS) approach was employed to monitor the N, P, K, S, Zn and Fe status of rice crop growing in 150 locations of Karimnagar district of Telangana and also to identify the yield limiting nutrients in rice. The population was divided into low (113 observations) and high yielding groups (37 observations) based on the third quartile method for developing the DRIS foliar diagnostic norms. Index leaf samples were collected from all the selected rice fields at tillering stage and analyzed for N, P, K, S, Zn and Fe contents. A wide range of variation in chemical composition of index leaves was observed irrespective of yield level. Based on critical nutrient concentration (CNC), the deficiencies of N, S, Zn and Fe contents were observed in rice crop under study to an extent of 40, 44, 53 and 10%, respectively, and no deficiencies were observed with respect to P and K. The extent of nutrient deficiencies diagnosed by CNC method varied depending upon the critical level adopted. There was poor correlation between N, P, K, S, Zn and Fe contents in index leaves and rice yields. Based on the highest variance ratio between low and high yielding populations, forms of expression for different nutrients and their norms were selected. The DRIS norms were established for various nutrient ratios obtained from high yielding population of rice crop and were further used to compute the DRIS indices assessed the yield limiting nutrients and their requirement in order of priority were addressed. The number of nutrients diagnosed as yield limiting by DRIS was more than those identified by the CNC method.