Comparison of high-yield rice in tropical and subtropical environments: II. Nitrogen accumulation and utilization efficiency uri icon

abstract

  • Nitrogen requirements to achieve rice grain yields higher than 13 t ha(-1) and the associated internal N-utilization efficiency (NUE) have not been documented. The objective of this study was to compare N accumulation and NUE of irrigated rice in tropical and subtropical environments at yield-potential levels in both climates. Field experiments were conducted in 1995 and 1996 at the International Rice Research Institute, Philippines (IRRI, tropical site), and at Taoyuan Township, Yunnan, China (subtropical site). Three to five high-yielding rice cultivars were grown under optimum crop management. Plants were sampled at key growth stages to determine tissue N concentration, plant N accumulation, N harvest index (NHI), N translocation ratio and NLTE. Plant N accumulation at maturity was 19 to 30% greater at Yunnan than at IRRI. Most of this difference resulted from greater N accumulation and N uptake rate during the vegetative period at Yunnan than at IRRI. During reproductive and grain-filling periods, N accumulation and N uptake rate were similar or higher at IRRI than at Yunnan, Grain N concentration at maturity was lower and N translocation ratio from straw to grains during grain filling was higher at Yunnan than at IRRI, and these traits contributed to larger NHI and NUE at Yunnan than at IRRI. Cultivars that produced grain yields over 13 t ha(-1) at Yunnan required the accumulation of about 250 kg N ha(-1) within the crop and had a NUE of 59 to 64 kg grain per kg plant N. (C) 1998 Elsevier Science B.V.

publication date

  • 1998
  • 1998
  • 1998