Nitrogen Partitioning and Translocation in Wheat under Fertilizer-N Levels, Application Time and Decapitation Stress

Abstract

The decapitation stress in dual purpose wheat can be managed by adopting proper fertilizer-N partitioning and translocation to get both more grain and fodder with higher amount of N-content. The fertilizer-N levels improved N-content at boot stage (24.37 g kg^-1), at anthesis stage (13.45 g kg^-1), at maturity stage (4.92 g kg^-1), grain N-content (18.38 g kg^-1), straw N uptake (43.34 kg ha^-1), grain N-uptake (58.81 kg ha^-1), apparent nitrogen re-translocation (14.88) and apparent nitrogen re-translocation efficiency (57.89) whereas reduced nitrogen harvest index (74.97 %) and nitrogen use efficiency (15.97) as compare to control. The decapitation stress reduced N-content at anthesis stage 12.90 g kg^-1, straw N-uptake (37.55 kg ha^-1), grain N-uptake (53.68 kg ha^-1), apparent nitrogen retranslocation (13.98), apparent nitrogen re-translocation efficiency (56.56) whereas enhanced nitrogen use efficiency (NUE), by 17.02 %. The increase in fertilizer-N level improved linearly N-content at boot stage (25.24 g kg^-1), at anthesis stage (13.71 g kg^-1), at maturity stage (5.11 g kg^-1), straw N-uptake (48.23 kg ha^-1), grain N-uptake (63.26 N kg ha^-1) but NHI (75.92 %), apparent nitrogen re-translocation (15.62) showed parabolic trend fertilizer-N level while the NUE reduced (13.21 % with 200 kg N ha^-1). The two equal split of fertilizer-N application time proved superior in the enhancement of N-content at boot stage, at anthesis stage, straw N-uptake (45.08 kg ha^-1) and NUE while the full with 2^nd irrigation application improved N-content at anthesis stage (13.87 g kg^-1),  straw N-uptake (44.35 kg ha^-1), apparent nitrogen re-translocation (15.88), apparent nitrogen re-translocation efficiency (59.91). Results suggest that NUE was increased with decapitation compared to non decapitated plants. Late application of N as full dose or even two equal splits applications at sowing and/or with 2^nd irrigation had improved the N content , total  N uptake, N re-translocation and its efficiency, grain protein, and NUE. The fertilizer-N level enhanced N-content at all growth stages, straw and grain. But NHI and apparent nitrogen re-translocation showed parabolic trend while reduced NUE.

Keywords: Nitrogen, Fertilizer-N, Fertilizer-N time, Fertilizer-N levels, Translocation, Re-translocation, nitrogen harvest index and NUE,