<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The objective of this study was to develop a mathematical model for the non-destructive, fast estimation of the leaf chlorophyll (Chl) content of pomegranate trees. For this reason, contact images of the leaf samples were firstly captured with smartphones and the RGB colours of the images were used for the estimation of the leaf Chl contents. Here, different methods were used for the contact imaging. In the present study, two closed boxes with a small hole (equal to the dimensions of a smartphone camera) on each were formed. Samples were inserted into the hole; and a red LED light and white LED light, separately, were passed through the hole and the leaf. Furthermore, a series of models were tested to best estimate the leaf chlorophyll content of the pomegranate trees by using the RGB colours of contact imaging. Results showed that the use of red LED light sources, instead of white LED light sources, during contact imaging, provides a better estimation of the leaf Chl content. Results also suggest that colour values are highly related to the total weight of the contact imaging area. According to the results obtained, the best estimation of the leaf Chl content (of a given area) is possible by using both the G and B colour values with multiple regression models. It is also found to be important to use the weight of the sampled area for the estimation of the leaf chlorophyll content in mg ∙ g<sup>−1</sup>.</p></abstract>

The objective of this study was to develop a mathematical model for the non-destructive, fast estimation of the leaf chlorophyll (Chl) content of pomegranate trees. For this reason, contact images of the leaf samples were firstly captured with smartphones and the RGB colours of the images were used for the estimation of the leaf Chl contents. Here, different methods were used for the contact imaging. In the present study, two closed boxes with a small hole (equal to the dimensions of a smartphone camera) on each were formed. Samples were inserted into the hole; and a red LED light and white LED light, separately, were passed through the hole and the leaf. Furthermore, a series of models were tested to best estimate the leaf chlorophyll content of the pomegranate trees by using the RGB colours of contact imaging. Results showed that the use of red LED light sources, instead of white LED light sources, during contact imaging, provides a better estimation of the leaf Chl content. Results also suggest that colour values are highly related to the total weight of the contact imaging area. According to the results obtained, the best estimation of the leaf Chl content (of a given area) is possible by using both the G and B colour values with multiple regression models. It is also found to be important to use the weight of the sampled area for the estimation of the leaf chlorophyll content in mg ∙ g−1.

Mathematical models for the estimation of leaf chlorophyll content based on RGB colours of contact imaging with smartphones: A pomegranate example

Faculty of Agricultural Sciences and Technologies

European University of Lefke, Gemikonağı

Folia Horticulturae

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The objective of this study was to develop a mathematical model for the non-destructive, fast estimation of the leaf chlorophyll (Chl) content of pomegranate...

RGB colours and combination indices	Red LED passed		White LED passed

	Chl (mg ∙ g⁻¹)	Chl (mg ∙ MW⁻¹)	Chl (mg ∙ g⁻¹)	Chl (mg ∙ MW⁻¹)
R value	−0.282	−0.552^**	−0.225	−0.257
G value	0.113	0.914^**	0.210	0.460^**
B value	0.146	0.893^**	−0.382^*	−0.364^*
NRI	−0.154	−0.914^**	−0.195	−0.424^**
NGI	0.148	0.918^**	0.344^*	0.476^**
NBI	0.172	0.897^**	−0.384^*	−0.371^*
GMR	0.280	0.571^**	0.279	0.484^**
GMB	0.000	0.756^**	0.287	0.456^**
GRRI	0.146	0.917^**	0.233	0.450^**
GRVI	0.144	0.916^**	0.302	0.475^**
DGCI	0.280	0.574^**	−0.014	0.009

	Coefficients	Standard error	t Stat	p-value
Intercept	−0.0914	0.017741	−5.1518	1.18E-05
G	0.1537	0.055322	2.7782	0.008948
B	−0.0019	0.071268	−0.0271	0.978541

Mathematical models for the estimation of leaf chlorophyll content based on RGB colours of contact imaging with smartphones: A pomegranate example

Article Category: Research Article

Pubblicato online: 22 apr 2020

Pagine: 57 - 67

Ricevuto: 15 gen 2020

Accettato: 13 feb 2020

DOI: https://doi.org/10.2478/fhort-2020-0006

Parole chiave
colour index, computer programs, fast estimation, multiple regression analysis, plant health, sustainable farming

© 2020 Nurdan Özreçberoğlu et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Figure 2

Figure 3

Correlation between the RGB colours and combination indices and leaf chlorophyll contents (for both mg ∙ g−1 and mg ∙ MW−1) of a pomegranate tree

Summary results for multiple regression analysis among G value, B value and Chl (Y)

Mathematical models for the estimation of leaf chlorophyll content based on RGB colours of contact imaging with smartphones: A pomegranate example

Article Category: Research Article

Pubblicato online: 22 apr 2020

Pagine: 57 - 67

Ricevuto: 15 gen 2020

Accettato: 13 feb 2020

DOI: https://doi.org/10.2478/fhort-2020-0006

Parole chiavecolour index, computer programs, fast estimation, multiple regression analysis, plant health, sustainable farming

© 2020 Nurdan Özreçberoğlu et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Figure 2

Figure 3

Correlation between the RGB colours and combination indices and leaf chlorophyll contents (for both mg ∙ g−1 and mg ∙ MW−1) of a pomegranate tree

Summary results for multiple regression analysis among G value, B value and Chl (Y)

Parole chiave
colour index, computer programs, fast estimation, multiple regression analysis, plant health, sustainable farming