Reducing nitrogen rate and hill distance improves rice dry matter production in saline–alkali soils

Abstract

AbstractThe integrated strategies for nitrogen management and planting density are important for improving rice (Oryza sativa L.) yield in saline–alkali soil; however, the optimal growth conditions for the Songnen Plain, China, are unclear. Here, we studied the effects of nitrogen application rate (NAR) (N0, 0 kg ha−1; N1, 90 kg ha−1; N2, 120 kg ha−1; N3, 150 kg ha−1; N4, 180 kg ha−1) and hill distance (HD) (HD1, 16.5 cm; HD2, 13.3 cm; HD3, 10 cm) on rice dry matter accumulation, translocation, and photosynthetic production in a split‐plot experiment. At NARs below 120 kg ha−1, the number of effective tillers increased significantly with increasing NAR and decreasing HD. The leaf area index (LAI) increased as the NAR increased and HD decreased and was the highest in the N4–HD3 treatment, followed by N3–HD3, at the full‐heading stage. However, dry matter accumulation from the full‐heading to the maturity stage was the highest in the N3–HD3 treatment. The population growth rate in N3–HD3 was the highest from the full‐heading stage to the maximum grain‐filling stage, at 26.46 g m−2 d−1. The high rice yield under N3–HD3 conditions was attributed to the high dry matter accumulation after the full‐heading stage and the high sheath output rate. This study revealed that treatment N3–HD3 resulted in high yield, from the perspective of photosynthetic matter production.