Nutrient accumulation and utilization in rice under film-mulched and flooded cultivation

In recent years, plastic film mulched cultivation has been widely used in China as a strategy to reduce irrigation water consumption and increase water use efficiency (WUE). Experiments were conducted to study nitrogen (N), phosphorus (P), and potassium (K) accumulation and utilization in flooded rice comparing plastic film mulched (PFM) and conventionally flooded cultivation (CFC) in two successive years. In comparison with the plants under CFC, the plants under PFM had significantly higher N concentration at booting stage and lower K and P concentrations at heading and maturity stages and N concentrations after booting stage. More N accumulation was found in PMC-treated plants than in CFC-treated plants before booting, while thereafter CFC showed a significant increase in nutrient accumulation. N, P, and K accumulation ratios were significantly larger for PFM than for CFC at early stage (before booting), but the trend was just opposite after booting. The PFM-treated plants substantially showed smaller nutrient accumulation rate through the whole growing process relative to the CFC-treated plants. Although PFM-treated plants had significantly higher physiological efficiency (PE) of all three nutrients than the CFC-treated plants, its fertilizer recovery efficiency (RE) and agronomic nutrient utilization efficiency (AE) was markedly lower due to lower biomass and grain yield. In addition, the PFM-treated plants had lower P/N and K/N in terms of nutrient accumulation, suggesting the importance to improve the P and K availability in rice film-mulched cultivation.