Estimation of Leaf, Root, and Sap Nitrogen Status using the SPAD‐502 Chlorophyll Meter for Ornamental Shrubs

Abstract

The SPAD-502 chlorophyll meter was evaluated as a rapid tool to predict plant nitrogen (N) concentration. The SPAD-502 index utility, as a comparative tool with respect to N nutritional status, was evaluated for Laurustine (Viburnum tinus L.), tobir (Pittosporum tobira Thumb.), and strawberry tree (Arbutus unedo L.). The effect of sampling time on the SPAD-502 index measures was also evaluated. Two sand culture experiments evaluating 1, 3, 5, and 7 mmol c . L 21 of total N concentration in nutrient solution and 70/30, 50/50, 40/60, and 30/70% nitrate/ ammonium (NO 3 2 /NH 4 þ ) ratios were applied. In a media experiment, with similar conditions and fertilization, the accuracy of the SPAD-502 regression data was evaluated. Leaf, root, and sap samples were taken in the middle and at the end of each experiment. Regression equations were established among leaf N, root N, of sap N analyzed concentrations and SPAD values with regard to global, as well as specific, data within each sampling time. Regression coefficients (b) among leaf N and SPAD were highly significant (P , 0.05) for practically all sampling times. However, liner regression equations were different in all treatments among all the sampling dates. Determination coefficients (R 2 ), in some cases, show that the SPAD-502 index is not an adequate method for leaf, root, or sap N concentration fir Viburnum tinus L. and Pittosporum tobira Thumb. or for root or sap for Arbutus unedo L. in these experimental conditions. Nonetheless, the SPAD-502 index could be a useful tool for relative comparison purposes and field operational nutrient management. However, the SPAD-502 leaf greenness meter is a relatively

Use of an Active Canopy Sensor and SPAD Chlorophyll Meter to Quantify Geranium Nitrogen Status

“…In N-deficient plants, because of low chlorophyll content, the red reflectance is much higher, whereas the infrared region is much lower (Ajay et al, 1984). For some species, correlation between SPAD meter reading and leaf N concentration is low (Martín et al, 2007), and for broad leaf species, multiple measurements per leaf are required to acquire a representative SPAD value for a leaf greatly reducing the speed of acquisition (Chang and Robison, 2003).…”

Nitrate Dynamic in a Tropical Mollisol Amended with Organic Manures, Planted with Sweet Corn, and Monitored with SPAD Readings

“…The SPAD 502 determines the relative amount of chlorophyll present by measuring the transmittance of the leaf in two wave bands (600-700 and 400-500 nm). It gives a reading in arbitrary unit that is proportional to the amount of chlorophyll present, which could be used to predict crop N requirements (Blackmer and Schepers 1995;Martin et al 2007). Waskom et al (1996) reported that the SPAD 502 worked very well at the rapid growth and tasselling stages of corn.…”

“…Schroeder et al (2000) reported that leaf relative chlorophyll content (RCC) measured by the SPAD 502 could not quantify the excess available N during early stages of corn crop compared to the values predicted by soil N content. Martin et al (2007) used the SPAD 502 chlorophyll meter as a rapid tool to evaluate N status in plant leaves, sap, and roots of various ornamental shrub plants and recommend it for field crops. They also indicated that even though the SPAD 502 leaf greenness index was adequate for leaf N and nutritional diagnosis of strawberry plant (Arbutus unedo L.), it was not suited for lauristine (Viburnum tinus L.), taboir (Pittosporum tobira), and thumb (Cotoneaster spp).…”

Escarola (Cichorium endivia L.): sistemas de manejo y ciclos como factores de la incidencia de fisiopatías y la acumulación de nitratos.

“…(Soil Plant Analysis Development) que determina la concentración de clorofilas de las hojas de una manera no destructiva, mediante diferencias en la transmitancia de la luz emitida por dos diodos a dos longitudes onda, 650 nm (rojo) y 940 nm (infrarrojo) (Monje, Bugbee, 1992;Blackmer, Schepers, 1995;Chang, Robinson, 2003;Martín et al, 2007).…”

“…Las unidades SPAD se han relacionado con la concentración de clorofila determinada mediante extracción en numerosos cultivos hortícolas como la lechuga, el tomate, el algodón o el maíz, constatándose en todos ellos, que puede ser una herramienta útil para estimar el contenido en clorofilas de manera no destructiva (Finnan et al, 1997;Rodriguez et al, 1998;Martín et al, 2007;León et al, 2007).…”