Microwave‐oven drying of rice leaves for rapid determination of dry weight and nitrogen concentration uri icon

abstract

  • Predicting the need for fertilizer-nitrogen (N) topdressing based on plant N status is an important N management strategy for increasing both grain yield and N-use efficiency of irrigated rice. Plant N analysis by conventional-oven drying and micro-KjeIdahl procedure generally requires several days. Accurate estimation of leaf N content per unit dry weight (NDW) at different growth stages by the chlorophyll meter requires that meter-reading values (SPAD values) be adjusted for specific leaf weight (SLW). This study demonstrated that a microwave oven can be used for drying rice leaves for quick estimation of leaf dry weight without significantly influencing the estimation of NDW by micro-Kjeldahl. procedure. Microwave oven drying of 0.5 g (dry weight) leaf samples required only two minutes. Extended exposure duration up to six minutes did not alter the measured Kjeldahl N concentration. Specific leaf weight determined with microwave-oven drying improved the prediction of NDW by SPAD. The chlorophyll meter with SLW adjustment can provide another tool to make rapid, in-season diagnosis of crop N status.

publication date

  • 1994
  • 1994
  • 1994