Protein and N-use efficiency of rainfed wheat responses to supplemental irrigation and nitrogen fertilization

Abstract

The purpose of this study was to investigate the interaction effects of supplemental irrigation and nitrogen fertilization on grain protein yield, protein content and nitrogen use efficiency of rainfed wheat. An experiment was laid out in complete randomized two-factorial split-strip block design with supplemental irrigation (SLIR) treatments as without irrigation (Io), 30 mm irrigation water (IW) at the flowering stage (I1), 25 mm IW at the grain filling stage (I2) and 55 mm IW at the flowering (FS) and grain filling stage (I3) and nitrogen application (N) treatments as without nitrogen fertilization (N0), net nitrogen as 30 (N1), 60 (N2) and 90 (N3) kg ha−1. All treatments received 326 mm precipitation during growing season. Results revealed that GPC will be increased with increasing N; and decreasing received water at the FS and grain filling stages (GFS). The highest and lowest GPC were 13.3 and 12.0% achieved from plots with I0N3 and I3N0 treatments. SLIR at GFS and FS + GFS produced the highest nitrogen use efficiency of 33.9 kg grain (kg nitrogen)−1 in the plots with N1I2 and N1I3 treatments. The protein yield (PY) increased with increasing in nitrogen application rates. The highest PY (701 kg ha−1) produced by nitrogen rate of 90 kg ha−1. Single irrigation at the GFS increased PY as 27% relative to rainfed production. The influence N and received water on GPC and PY were described by regression models.