Response of rice varieties to different levels of nitrogen during Kharif season in Northern Telangana agroclimatic zone of Telangana state India

Effect of nitrogen (N) levels on yield and yield components of rice cultivars was investigated in an experiment as split plot design with three replications in a paddy at Regional Agricultural Research Station, Jagtial, Karimnagar district of Telangana state in India. During kharif 2010 and 2011. Four rice varieties viz; JGL 17004 (Pradhymna), JGL 13545, JGL -11118(Anjana) and JGL-11727 (Pranahitha) were tested as pre released cultures for their response to graded levels of nitrogen viz; 100% RDN (100 kg recommended dose of nitrogen per ha), 125% RDN, 150% RDN and 175% RDN. Results showed that 175%RDN recorded significantly superior grain yield (5039 Kg/ha) over100% & 125% RDN, that was 11.5 %, 8.4 % and 1.5% higher over 100 % RDN, 125% RDN and 150% RDN respectively. While 150% RDN recoded comparable yield (4960 kg /ha) with 175% RDN. Among the varieties JGL 11727 & JGL13595 were found superior, recorded the grain yield of 5347 kg/ha & 5345 kg/ha, The regression pertaining to quadratic functions are highly significant. Further, the regression for the quadratic term N was positive in all the cases suggesting that grain yield increased quadratically. From initial increments of this input. But, the negative second power regression coefficient (N)2 suggested that the grain yield increased at diminishing rate at higher levels of Nitrogen.