Asian Journal of Agricultural Research1819-1894xxxx-xxxxKnowledgia Review10.3923/ajar.2008.37.40Oryza sativa) in Systems of Cultivation with Varied N Levels Under 15N Tracer Technique]]>KumarG. Senthil RajarajanA. ThavaprakashN. BabuC. UmashankarR. 1200821A pot culture experiment was conducted at the Tamil
Nadu Agricultural University, Coimbatore, to study the Nitrogen Use Efficiency
(NUE) of rice under different eco-systems. The different eco-systems of
rice cultivation evaluated in the study were i) direct seeding of sprouted
seeds under puddled condition, direct seeding of ii) sprouted and iii)
dry seeds under unpuddled condition and iv) transplanting of rice seedlings
under unpuddled condition. In the puddled soil condition pots, 5 cm depth
of water was maintained throughout the crop growing period. In respect
of unpuddled condition pots, 5 cm depth of irrigation was given at 80%
of the available soil moisture condition. The nitrogen levels were 50,
75, 100, 125 and 150% of recommended dose of nitrogen. Nitrogen tracer
(15N) technique is an accurate tool to assess the absorption
and distribution of added N in the soil crop environment, as influenced
by the nitrogen levels. Assaying on 15N tracer added as labelled
urea in rice brought out valid information in the present study on quantity
of N derived as crop recovery (N use efficiency). The N use efficiency
under 15N study was higher in direct seeding of sprouted seeds
under puddled condition. Among the different N levels, increasing the
N level up to the recommended level (100%), the N use efficiency was increased.
Further, increasing the N levels to 125 and 150%, the N use efficiency
was decreased under all the systems of cultivation. It may be due to the
application of excess nitrogen, which was not effectively utilized by
the crop and the rate of production was lesser per unit of N application.]]>Bindu, C.J.,20022002Dubey, Y.P.,199565676678Jaiswal, V.P. and G.R. Singh, 2000Oryza sativa L.) as influenced byplanting method, source and level of nitrogen.]]>371013Lu, W., C.W. Lindan and W.H. Jr. Patrick,199815N by rice.]]>132526Pandey, S. and L.Velasco,199924611