Proposed diagrammatic scale to assess heat injury in coffee seedling canopy

A diagrammatic scale with five levels (0, 0.1 - 2.0, 2.0 - 6.0, 6.0 - 10, and 10 - 14) was developed and evaluated to measure the symptoms of heat injury in a coffee seedling canopy. The scale was constructed to increase assessment efficiency and align the estimations more closely with the actual values. Two assessments with the diagrammatic scale and one without were conducted with an interval of seven days. The evaluators using the proposed scale presented estimates with better levels of precision, accuracy, reproducibility, and repeatability than those using a conventional method. The proposed diagrammatic scale was shown to provide a reliable estimate for assessing the symptoms of heat injury on the canopy of in Coffea arabica L. seedlings. Therefore, it is possible to standardize heat injury evaluation methods using this diagrammatic scale, allowing for data comparisons with different cultivars.

Keywords:
Coffea arabica L.; Lin´s method; temperature and water stress.

Authorship

Laís Sousa Resende ^** Author for correspondence. E-mail: sialresende@gmail.com

Departamento de Agricultura, Universidade Federal de Lavras, 37200-000, Lavras, Minas Gerais, Brazil. Universidade Federal de LavrasBrazilLavras, Minas Gerais, BrazilDepartamento de Agricultura, Universidade Federal de Lavras, 37200-000, Lavras, Minas Gerais, Brazil.

https://orcid.org/0000-0002-3647-9725

Edson Ampélio Pozza

Departamento de Fitopatologia, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil. Universidade Federal de LavrasBrazilLavras, Minas Gerais, BrazilDepartamento de Fitopatologia, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil.

Renata Cristina Martins Pereira

Élberis Pereira Botrel

Karolaine de Cássia Roteli

Júlia Marques Oliveira

* Author for correspondence. E-mail: sialresende@gmail.com

SCIMAGO INSTITUTIONS RANKINGS

Figures | Tables

Figures (1)
Tables (5)

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Figure 1
Diagrammatic scale to quantify the percentage severity of heat injury in coffee seedlings (Coffea arabica L.). Numbers below each picture represent the actual percentage of leaf area affected by thermal and water stress.

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Table 1
Frequency distribution of severity values of heat injury in coffee seedlings at unit intervals (%).

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Table 2
Parameters of the linear and non-linear models for the frequency of heat injury in coffee by severity interval.

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Table 3
Lin’s concordance correlation coefficients for 8 evaluators without or with the use of the diagrammatic severity scale for estimating heat injury in coffee seedlings.

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Table 4
Coefficients of determination (R²) of the linear regression equation between pairs of different evaluators, with or without the use of the heat injury severity assessment scale in two evaluations estimating the damage severity on coffee seedlings.

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Table 5
Intercept (β₀), slope (β₁), and coefficient of determination (R²) of the linear regression equations relating to the first and second estimates of heat injury severity on seedlings, for estimates performed by 8 evaluators using the heat injury severity scale.

Figure 1 Diagrammatic scale to quantify the percentage severity of heat injury in coffee seedlings (Coffea arabica L.). Numbers below each picture represent the actual percentage of leaf area affected by thermal and water stress.

Table 1 Frequency distribution of severity values of heat injury in coffee seedlings at unit intervals (%).

Interval (Severity %)	Frequency
0 - 1	28
1 - 2	11
2 - 3	1
3 - 4	3
4 - 5	6
5 - 6	1
6 - 7	0
7 - 8	1
8 - 9	1
9 - 10	1
10 - 11	1
11 - 12	0
12 - 13	1
13 - 14	1

Table 2 Parameters of the linear and non-linear models for the frequency of heat injury in coffee by severity interval.

Models	Y₀ ^c	R^b	QMR	R^2a
Linear	25.43*	-2.18	123.29	0.46
Monomolecular	340.42	1.09*	6.81	0.97
Exponential	253.17	-0.94*	10.11	0.96
Gompertz	2049.04	0.37*	5.38	0.98

a) Coefficient of determination (R²); b) Progress rate (R); c) Initial heat injury (Y₀); *significant according to the t-test (p = 0.05).

Table 3 Lin’s concordance correlation coefficients for 8 evaluators without or with the use of the diagrammatic severity scale for estimating heat injury in coffee seedlings.

Lin´s statistic	Without scale	With scale	95% CI^c
Lin’s concordance correlation coefficient	0.24	0.82	0.47-0.69
Scale shift factor ^a	4.74	0.82	1.61-3.28
Location shift factor ^b	1.18	-0.26	0.05-0.74
BIAS correction factor	0.31	0.94	0.53-0.78
Pearson’s correlation	0.76	0.86	0.86-0.90

^aScale shift factor relative to perfect agreement. ^bLocation shift factor relative to perfect agreement. ^cUpper and lower limits of the 95% confidence intervals. ^Boldrepresents a significant difference (p ≤ 0.05) between the two evaluations, according to the t-test.

Table 4 Coefficients of determination (R²) of the linear regression equation between pairs of different evaluators, with or without the use of the heat injury severity assessment scale in two evaluations estimating the damage severity on coffee seedlings.

Without scale
Evaluator	B	C	D	E	F	K	L
A	0.88	0.87	0.82	0.79	0.59	0.77	0.86
B		0.88	0.86	0.80	0.65	0.77	0.81
C			0.90	0.85	0.69	0.62	0.78
D				0.82	0.74	0.64	0.78
E					0.72	0.52	0.78
F						0.40	0.63
K							0.64
With scale - 1^st assessment
Evaluator	B	C	D	E	F	K	L
A	0.65	0.79	0.74	0.62	0.84	0.46	0.51
B		0.87	0.86	0.81	0.76	0.68	0.85
C			0.92	0.74	0.85	0.66	0.79
D				0.71	0.83	0.63	0.82
E					0.77	0.74	0.65
F						0.63	0.65
K							0.61
With scale - 2^nd assessment
Evaluator	B	C	D	E	F	K	L
A	0.57	0.70	0.73	0.63	0.72	0.72	0.65
B		0.73	0.65	0.70	0.72	0.76	0.46
C			0.93	0.87	0.78	0.89	0.62
D				0.81	0.75	0.85	0.62
E					0.72	0.76	0.75
F						0.72	0.58
K							0.48

Table 5 Intercept (β₀), slope (β₁), and coefficient of determination (R²) of the linear regression equations relating to the first and second estimates of heat injury severity on seedlings, for estimates performed by 8 evaluators using the heat injury severity scale.

Evaluator	β₀	β₁	R²
A	0.30 ^ns	0.68 ^ns	0.58
B	0.01 ^ns	0.58 ^ns	0.76
C	0.12 ^ns	0.96 ^ns	0.90
D	0.37 *	0.89 ^ns	0.83
E	0.25 ^ns	1.23 ^ns	0.74
F	0.11 ^ns	0.61 ^ns	0.82
K	0.23 ^ns	0.76 ^ns	0.67

*ns represent situations where the null hypothesis (β₀ = 0 or β₁ = 1) was rejected or not rejected, respectively, according to the t-test (p = 0.05).

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Proposed diagrammatic scale to assess heat injury in coffee seedling canopy

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[1] * Author for correspondence. E-mail: sialresende@gmail.com