Relationship between specific leaf area, leaf thickness, leaf water content and SPAD-502 readings in six Amazonian tree species
ABSTRACT The aim of this work was to assess the effect of leaf thickness, leaf succulence (LS), specific leaf area (SLA), specific leaf mass (Ws) and leaf water content (LWC) on chlorophyll (Chl) meter values in six Amazonian tree species (Carapa guianensis, Ceiba pentandra, Cynometra spruceana, Pithecolobium inaequale, Scleronema micranthum and Swietenia macrophylla). We also tested the accuracy of a general calibration equation to convert Minolta Chl meter (SPAD-502) readings into absolute Chl content. On average, SPAD values (x) increased with fresh leaf thickness (FLT [μm] = 153.9 +
0.98 x, r
2 = 0.06**), dry leaf thickness (DLT [μm] = 49.50 + 1.28 x, r
2 = 0.16**), specific leaf mass (Ws [g (DM) m−2] = 6.73 + 1.31 x, r
2 = 0.43**), and leaf succulence (LS [g(FM)] m−2 = 94.2 + 1.58 x, r
2 = 0.19**). However, a negative relationship was found between SPAD values and either specific leaf area [SLA (m2 kg−1) = 35.1 − 0.37 x, r
2 = 0.38**] or the leaf water content (LWC [%]= 80.0 − 0.42 x, r
2 = 0.58**). Leaf Chl contents predicted by the general calibration equation significantly differed (p<0.01) from those estimated by species-specific calibration equations. We conclude that to improve the accuracy of the SPAD-502 leaf thickness and LWC should be taken into account when calibration equations are to be obtained to convert SPAD values
into absolute Chl content.
- SourceAvailable from: Yong-jiang Zhang[Show abstract] [Hide abstract]
ABSTRACT: * Cycads are the most ancient lineage of living seed plants, but the design of their leaves has received little study. We tested whether cycad leaves are governed by the same fundamental design principles previously established for ferns, conifers and angiosperms, and characterized the uniqueness of this relict lineage in foliar trait relationships. * Leaf structure, photosynthesis, hydraulics and nutrient composition were studied in 33 cycad species from nine genera and three families growing in two botanical gardens. * Cycads varied greatly in leaf structure and physiology. Similarly to other lineages, light-saturated photosynthetic rate per mass (Am) was related negatively to leaf mass per area and positively to foliar concentrations of chlorophyll, nitrogen (N), phosphorus and iron, but unlike angiosperms, leaf photosynthetic rate was not associated with leaf hydraulic conductance. Cycads had lower photosynthetic N use efficiency and higher photosynthetic performance relative to hydraulic capacity compared with other lineages. * These findings extend the relationships shown for foliar traits in angiosperms to the cycads. This functional convergence supports the modern synthetic understanding of leaf design, with common constraints operating across lineages, even as they highlight exceptional aspects of the biology of this key relict lineage.New Phytologist 01/2015; · 6.55 Impact Factor
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ABSTRACT: Models were developed to estimate nondestructively chlorophyll (Chl) content per unit of leaf area (Chlarea) and nitrogen content per unit of leaf area (Narea) using readings of two optical meters for five warm-temperate, evergreen, broadleaved tree species (Castanopsis sieboldii, Cinnamomum tenuifolium, Eurya japonica, Machilus thunbergii, and Neolitsea sericea). It was determined whether models should be adjusted seasonally. Readings (were obtained six times during a year period and Chlarea and Narea were determined using destructive methods. Bayesian inference was used to estimate parameters of models that related optical meter readings to Chlarea or Narea for each species. Deviance information criterion values were used to select the best among models, including the models with seasonal adjustment. The selected models were species-specific and predicted Chlarea accurately (R 2 = 0.93–0.96). The best model included parameters with seasonal adjustments for one out of five species. Model-based estimates of Narea were not as accurate as those for Chlarea, but they were still adequate (R 2 = 0.64–0.82). For all species studied, the best models did not include parameters with seasonal adjustments. The estimation methods used in this study were rapid and nondestructive; thus, they could be used to assess a function of many leaves and/or repeatedly on individual leaves in the field.Photosynthetica 12/2013; 51(4). · 1.01 Impact Factor
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ABSTRACT: A chlorophyll meter can conveniently estimate foliar chlorophyll and nitrogen (N) contents in many species. The objective of this study was to evaluate the utility of a chlorophyll meter to inform nitrogen fertilization rates of tea (Camellia sinensis L.) at different places and times. Plot-scale (5 x 20 m) experiments with three replications were conducted in 2010. Each plot was treated with 248 kg pure N ha-1 per year as urea. At the same time, a field-scale (32 ha) experiment, with the same fertilization rate, was conducted at the same plantation. Tea leaves were sampled in August and November and analyzed with a chlorophyll meter in situ and in the lab. The chlorophyll and nitrogen contents and chlorophyll meter (SPAD) readings of tea leaves in August were greater than in November, and plot-scale values were greater than field-scale values. SPAD readings could estimate the chlorophyll content of tea leaves regardless of temporal and spatial considerations. However, space and time must be considered when using SPAD readings to estimate the nitrogen content of tea leaves.Journal of soil science and plant nutrition. 12/2011; 12(2):339-348.