Field evaluation of the chlorophyll meter to predict yield and nitrogen concentration of switchgrass
- 31 December 1998
- journal article
- research article
- Published by Taylor & Francis Ltd in Journal of Plant Nutrition
- Vol. 22 (6), 1001-1010
- https://doi.org/10.1080/01904169909365689
Abstract
Chlorophyll meters have been used to estimate leaf chlorophyll content, and therefore nitrogen (N) status and fertilization requirements for several crops. However, until now C-4 forage grasses have not been investigated in this regard. A field study was conducted in 1995 and 1996 to evaluate the potential of chlorophyll (SPAD) meter readings to determine switchgrass N concentration and herbage yield. Meter readings were taken on the top most fully expanded leaves of switchgrass grown on a free draining sandy clay loam soil (St Bernard, Typic Hapludalf) fertilized at 0, 75, or 150 kg N ha(-1). The switchgrass was either cut at the end of the season or every four or six weeks. Herbage N concentration in uncut stands declined with time while SPAD readings increased to a mid-season maximum, beyond which they declined rapidly. The relationship between N concentration and SPAD readings was linear (r(2)=0.62-0.93; p<0.01) for the cut systems. Except for the Ist cut under the 4-week harvest regime, there were positive correlations between dry matter yield and SPAD meter readings (r(2)=0.58-0.96; p<0.01). These results indicate that SPAD meter readings can be used to measure N concentration and/or monitor N availability for seed production, and when N is the limiting factor, to estimate yield of switchgrass (Panicum virgatum L.).This publication has 15 references indexed in Scilit:
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