Non-destructive estimation of chlorophyll and nitrogen content in leaf of Rosa damascena (Mill)

Figures & data

Figure 1. The linear and non-linear relationships between chlorophyll content index (CCI) and total chlorophyll (mg g⁻¹) (a), and CCI and nitrogen (N) content (%) (b) in leaves of the Damask rose (Rosa damascena Mill). R² is the coefficient of determination. Root mean square error for calibration (RMSEc) of respective regression lines are given in Table 1.

Figure 2. Validation of the developed models for estimating total chlorophyll (Chl) (a) and nitrogen (b) content in leaf. Solid lines are Chl _pred  = Chl _obj (a) and nitrogen _pred  = nitrogen _obj (b); dotted lines are best-fit function for predicted values versus observed values. *** indicates the level of significance (P < 0.001).

Table 1. Regression models and estimated parameters for non-destructive estimation of chlorophyll and nitrogen content

		Estimated parameters and statistics of developed models						Statistics for model validation
Dependent variable (Y)	Regression Models	α	β	γ	AIC	R^2	RMSEc	RMSEp	CV(%)
Total Chl	Linear (Y = α + βX)	1.1315	0.1696		−77.00	0.878	0.2469	0.2073	4.38
Nitrogen		1.4264	0.0768		−23.86	0.840	0.1917	0.2085	6.65
Total Chl	Exponential (Y = αe^βX)	2.1645	0.0363		−78.33	0.883	0.2415	0.1911	4.03
Nitrogen		1.7382	0.026		−22.42	0.846	0.1886	0.2239	7.14
Total Chl	Power (Y = αX^β)	0.5092	0.73		−75.54	0.870	0.2530	0.2147	4.53
Nitrogen		0.7057	0.4824		−25.34	0.815	0.2011	0.1936	6.17
Total Chl	(Y = α + βX + γX^2)	2.7257	0.0116	0.0038	−76.45	0.886	0.2383	0.1909	4.03
Nitrogen		1.9807	0.0164	0.0015	−18.37	0.847	0.1875	0.2341	7.45
Akaike Information Criterion (AIC), coefficient of determination (R^2) and root mean square error of calibration (RMSEc) were estimated for selection of models. Prediction accuracy of model was estimated using root mean square error of prediction (RMSEp) and coefficient of variance (CV) throughout cross-validation procedure. Chl, chlorophyll.

Figure 3. The best fitted regression line for estimating total chlorophyll (a) and nitrogen (b) content in leaf with 95% confidence intervals. The lower and upper dotted curved lines demarcate the range of the 95% confidence interval whereas the solid regression line itself represents the best-fit function for estimating total chlorophyll (a) and nitrogen (b). There is a 95% probability that the actual value is between the upper and lower confidence intervals. CCI, chlorophyll content index; CI, confidence interval.