ADJUSTMENT FOR SPECIFIC LEAF WEIGHT IMPROVES CHLOROPHYLL METERS ESTIMATE OF RICE LEAF NITROGEN CONCENTRATION
ADJUSTMENT FOR SPECIFIC LEAF WEIGHT IMPROVES CHLOROPHYLL METERS ESTIMATE OF RICE LEAF NITROGEN CONCENTRATION
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DOI：
10.2134/agronj1993.00021962008500050005x
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发表时间：
1993-09-01
期刊：
影响因子：
2.1
通讯作者：
CASSMAN, KG
中科院分区：
文献类型：
--
作者：
PENG, SB;GARCIA, FV;CASSMAN, KG
叶绿素仪提供了一种简单、快速、非破坏性的方法来评估水稻叶片氮素状况，但叶氮浓度（以干重为基础）（N（dw））和仪表阅读之间的线性关系因发育阶段和基因型而异。其目的是确定是否可以通过简单的比叶重（SLW）的校正，提高叶绿素计的N（dw）的预测。叶片氮素状况由叶绿素仪（SPAD-502）估计，并直接通过微型凯氏定氮法测量。比叶重计算为干重与叶面积的比率。在一个田间研究与'IR 72'，测量了在分蘖中期，穗分化，开花阶段的最高完全展开的叶片的N-缺乏和N-充足的植物。N（dw）与SPAD值在各生育期均呈线性关系，但各生育期的回归线差异显著。基于所有阶段的汇总数据，线性拟合度较差（r2 = 0.49）。调整SLW的SPAD值（SPAD/SLW）可提高N（dw）的预测值（r2 = 0.93）。对于在田间和温室中生长的五个基因型的旗叶上进行的另一组测量，N（dw）的预测也得到改善，从基于SPAD值单独的r2 = 0.51到基于SPAD/SLW比率的r2 = 0.87。这些结果表明，SLW影响叶绿素计的N（dw）的预测，和SLW的SPAD值的调整大大提高了预测的准确性。然而，当SPAD值调整SLW，叶绿素计的N（dw）的估计不再是快速，简单，或非破坏性的SPAD值未经调整。
The chlorophyll meter provides a simple, quick, and nondestructive method to estimate leaf N status of rice (Oryza sativa L.), but the linear relationship between leaf N concentration on a dry-weight basis (N(dw)) and the meter reading differs depending on developmental stage and genotype. The objective was to determine whether prediction of N(dw) with the chlorophyll meter can be improved by a simple correction for specific leaf weight (SLW). Leaf N status was estimated by a chlorophyll meter (SPAD-502) and measured directly by micro-Kjeldahl procedure. Specific leaf weight was calculated as the ratio of dry weight to leaf area. In one field study with 'IR72', measurements were taken at midtillering, panicle initiation, and flowering stages on the uppermost fully expanded leaves of both N-deficient and N-sufficient plants. There was a linear relationship between N(dw) and SPAD values at each stage, but regression lines differed significantly between growth stages. Based on pooled data from all stages, the degree of linear fit was poor (r2 = 0.49). Adjusting SPAD values for SLW (SPAD/SLW improved the prediction of N(dw) (r2 = 0.93). For another set of measurements made on the flag leaves of five genotypes grown in the field and greenhouse, prediction of N(dw) was also improved, from r2 = 0.51 based on SPAD values alone to r2 = 0.87 based on the SPAD/SLW ratio. These results demonstrate that SLW influences the prediction of N(dw) by the chlorophyll meter, and that the adjustment of SPAD values for SLW greatly increases the accuracy of the prediction. However, when SPAD values are adjusted for SLW, the chlorophyll meter's estimate of N(dw) is no longer as quick, simple, or nondestructive as the nonadjusted SPAD values.