CONTENTS

NUTRIENT UPTAKE OF MICROSPRINKLER IRRIGATED WHEAT CULTIVARS
reported by Mukherjee (2008) and Singh et al. (2010)
owing to their genetic makeup and yield potential.
Each higher level of nitrogen significantly
increased the nitrogen, phosphorus and potassium
uptake over its lower level up to 160 kg N ha -1 (N 160
)
(Table 1) due to increased grain yield. Application of
200 kg N ha -1 (N 200
) did not prove to be advantageous
over N 160
in improving the nutrient uptake. These
results are in conformity with those of Singh et al.
(2011). The interaction effect (V x N) was significant
on nitrogen, phosphorus and potassium uptake. The
NPK uptake pattern in relation to applied N is shown
in Fig. 1. The explained total variation (R 2 ) in NPK
uptake by applied N was significant and amounted
to 99.5%, 99.9% and 99.8%, respectively suggesting
that the nutrient uptake increased with increase in
applied N, but the increase in uptake was not
proportional to the applied N at higher levels (Fig. 1).
The maximum N uptake was not bracketed within
the administered N levels. The predicted maximum
N uptake of 74.6 kg ha -1 was obtained with 214.6 kg
applied N ha -1 . Whereas, the maximum uptake of P
(10.9 kg ha -1 ) and K (35.9 kg ha -1 ) occurred at applied
N levels of 163.7 kg and 171.0 kg ha -1 . Further the
nutrient uptake function did not emerge through the
origin and the value of regression constant (a) was
positive, indicating that some amount of nutrients
are taken up by the wheat crop from native fertility
status.
Fig. 1. Nutrient uptake as a function of applied nitrogen
The agronomic efficiency (AEN), recovery
efficiency (RE) and physiological efficiency (PE) as
influenced by different nitrogen levels is presented
in Fig. 2. Perusal of the Fig. 2 suggests that each
higher level of nitrogen linearly decreased the AEN,
RE and PE. The mean values of AEN, REN and PEN
were 10.37 kg grain kg -1 N, 0.32 kg N kg -1 N, 32.12
kg grain kg -1 N absorbed, respectively.
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