Growth Environment and Leaf Anatomy Affect Nondestructive Estimates of Chlorophyll and Nitrogen in Citrus sp. Leaves

Abstract

<jats:p>Correlations between extractable leaf chlorophyll (Chl) concentration and portable, nondestructive leaf “greenness” meter readings imply that such estimates can be used as surrogate measurements of leaf nitrogen (N) status. However, few studies have actually found a direct relationship between Chl meter readings and leaf N. We evaluated the utility of two handheld transmittance-based Chl content meters (SPAD-502, Minolta Corp. and CCM-200, Opti-Sciences) and one reflectance-based meter (Observer, Spectrum Technologies), in estimating Chl and N concentrations in intact leaves of several citrus cultivars. Total Chl determined analytically, correlated well with nondestructive Chl meter readings (<jats:italic>r</jats:italic><jats:sup>2</jats:sup>: 0.72 to 0.97; <jats:italic>P</jats:italic> &lt; 0.0001), but regression models differed among cultivars using the same meter and also among meters for a given cultivar. The relationships were generally more linear and stronger at low Chl concentrations (&lt;0.5 mmol·m<jats:sup>-2</jats:sup>) than at higher Chl concentrations, reflecting increased variability in Chl meter readings with increasing leaf Chl. Significant relationships between Chl meter readings and measured leaf N concentrations were also found in all the cultivars tested (<jats:italic>r</jats:italic><jats:sup>2</jats:sup>: 0.23 to 0.69; <jats:italic>P</jats:italic> &lt; 0.01), but the data were more variable than those for Chl. Field-grown leaves were significantly thicker and had higher Chl meter readings than greenhouse-grown leaves of similar Chl or N concentrations. The results suggest that nondestructive Chl content meters can overestimate Chl and N in thicker leaves and/or leaves with high Chl concentrations. A single prediction equation derived from a wide range of Chl or N concentrations could be applicable across the range of citrus cultivars when grown in the same environment. Potential limitations associated with leaf thickness as influenced by environmental factors may necessitate the development of more specific calibration equations.</jats:p>

Relationship between specific leaf area, leaf thickness, leaf water content and SPAD-502 readings in six Amazonian tree species

“…In this work, the effect of W S , SLA and leaf thickness on SPAD values concurs with those reported by others, either for Citrus (Jifon et al 2005) or Sorghum sp. and Cajanus cajan (Yamamoto et al 2002).…”

“…Indeed, calibration equations can even be specific for cultivars within the same species, as observed in Citrus sp. (Jifon et al 2005). Although in some other studies similar calibrations have been obtained for different species (Gratani 1992;Markwell et al 1995), hybrids or cultivars within the same species (Dwyer et al 1991, Uddling et al 2007).…”

Response of ‘Clausellina’ Satsuma mandarin to 3,5,6-trichloro-2-pirydiloxyacetic acid and fruitlet abscission

“…In our study, this phytotoxicity has been associated with ethylene produced in the fruit at the same time as in the leaves (Hirose 1981). The level of phytotoxicity, measured by leaf chlorophyll content (Jifon et al 2005), can cause a reduction of photosynthetic efficiency (Mesejo et al 2005), which can give rise to lower fruit growth rates. In Citrus, there is apparently a threshold value for fruit size beyond which abscission is not experienced (Agustí et al 1982).…”

Estimation of leaf nitrogen concentrations in Quercus robur L. using the CCM-200 portable chlorophyll meter for different patterns of vegetative growth and acorn production

“…These chlorophyll meters have been described many times as potentially suitable tools for the assessment of the total nitrogen (N) content in the leaves of a large number of crops (Wood et al 1992;Bullock and Anderson 1998;Rodriguez and Miller 2000;Jifon et al 2005;Rostami et al 2008) and for several forest tree species (Loh et al 2002;Chang and Robison 2003;Van den Berg and Perkins 2004;Percival et al 2008).…”

“…In this case, a positive correlation between the CCI and the total N amount in leaves rests on the existence of a close relationship between the amount of chlorophyll in the leaves and N, which builds proteins that connect chlorophyll molecules with thylakoid membranes of chloroplasts (Jifon et al 2005). However, in addition to N within chlorophyll-protein complexes, the total N in leaves includes N that builds other structural and metabolic components of leaves (Yasumura et al 2006;Funk et al 2013).…”