Non-destructive determination of leaf chlorophyll content in four crop species
A recent non-destructive technique allows estimation of leaf chlorophyll content using the portable SPAD-502 chlorophyll meter. Measurements were taken on four species (winter wheat, maize, soyabean and tobacco) subjected to different nitrogen regimes or senescence status and the: non-destructive readings were compared with analytical results obtained by solvent extraction. In general, the relationship between the SPAD measurement and the analytical result was not linear and species was a factor in three out of four crops. Linear, quadratic and exponential curve fitting are presented; only die interpolation with a polynomial exponential function adequately descries the whole data set. The presence of statistically non-significant differences between the estimated values of wheat and maize on the one hand and significant: points of difference between those of tobacco and soyabean on the other suggests distinct behaviour patterns far monocots and cicots. This type of response maybe explained by differences, in the optical properties of pigments with differing sparial distributions (sieve effect) and therefore by in vivo and in vitro different procedures and the structural diversity of leaves belonging to the two subclasses.
Nondestructive and Rapid Estimation of Leaf Chlorophyll and Nitrogen Status of Peace Lily Using a Chlorophyll Meter
Timely and nondestructive detection of leaf nitrogen (N) status could greatly improve nutrient management practices for greenhouse ornamental production. This study evaluated the feasibility of using a SPAD-502 chlorophyll meter for estimating leaf chlorophyll and nitrogen contents of the peace lily (Spathiphyllum Schott). Three cultivars ‘Claudia’, ‘Double Take’, and ‘Petite’ were grown in a soilless substrate and sub-irrigated with solutions containing N at 50, 100, 200, or 400 mg L−1 through an ebb-and-flow system. The SPAD-502 chlorophyll meter was used to measure leaf greenness. Chlorophyll contents of leaves were also analyzed using the dimethyl sulphoxide extraction method. Total N was determined by a CNS Auto-Analyzer. Correlation analyses showed that coefficients (r 2) between SPAD values and leaf chlorophyll contents were 0.83, 0.77, and 0.73 for ‘Claudia’, ‘Double Take’, and ‘Petite’, respectively, and coefficients (r 2) between SPAD values and leaf N contents of ‘Claudia’, ‘Double Take’, and ‘Petite’ were 0.84, 0.82, and 0.91, respectively. These results suggest that the readings from a SPAD meter can be used for rapidly and nondestructively estimating leaf chlorophyll and N status of the peace lily. As high quality Spathiphyllum were produced at the N concentration of 200 mg L−1, the corresponding SPAD values established in this study could facilitate in situ decision-making on N application for the production of the peace lily. #This research was supported by the Florida Agricultural Experiment Station and approved for publication as Journal Series No. R-09531.
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