Efficiency and response of rice genotypes to nitrogen application in tamirabarani command area of Tamil Nadu

Nitrogen (N) is one of the most yield-limiting nutrients in lowland rice production around the world. Use of N efficient genotypes is an important complementary strategy in improving rice yield and reducing cost of production. In this sense, the experiment was conducted during October 2017 to January 2018 with four N levels (0, 50, 100 and 150% recommended doses of N fertilizer) and the thirty two short duration rice genotypes popular in all rice growing areas of Tamil Nadu. The objective was to screen promising rice genotypes by determining agronomic N use efficiency (ANUE) of different N levels and classify the rice genotypes into responsive and efficient cultures / varieties. The results revealed that grain yield and yield components were significantly affected by genotypes, N levels and interaction of genotypes and N levels. On the basis of ANUE and grain yield under no-N, genotypes were classified as efficient and responsive (ER), efficient and nonresponsive (ENR), non-efficient and responsive (NER), and non-efficient and nonresponsive (NENR). The genotypes ASD16, ADT45, ACK14001, ACK14004, AS12104, CB14508, TR05031 and TM12077 were classified as efficient and responsive rice genotypes to N application. The genotypes which fall into the efficient and responsive group are the most desirable. Because these genotypes can produce more at a low N level and also respond well to applied N. This means this type of genotype can be utilized under low as well as high N levels with reasonably good yield.