Estimating optimum plot size with radiometer for experiments on soybeans treated with fungicide

Michels, Roger Nabeyama; Canteri, Marcelo Giovanetti; Fonseca, Inês Cristina de Batista; Silva, Marcelo Augusto Aguiar e; Bertozzi, Janksyn; Bosco, Tatiane Cristina Dal

doi:10.1590/0100-5405/238411

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ARTIGOS • Summa Phytopathol. 46 (4) • Oct-Dec 2020 • https://doi.org/10.1590/0100-5405/238411 copy

Estimating optimum plot size with radiometer for experiments on soybeans treated with fungicide

Estimativa do tamanho ótimo de parcela em experimentos com o radiômetro em soja tratada com fungicida

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Spectral remote sensing and proximal sensors are important tools for managing the plant-pathogen relationship. The lack of experimental planning and the probability of error in agricultural studies may result in work repetition and, consequently, in financial expenses and costs with human resources. To reduce such problems, determining the optimum size of the experimental plot for treatments is one of the adopted methods. The objective of this study was to estimate the optimum plot size for reflectance in soybeans that were treated with different fungicide levels according to the methods of modified maximum curvature and maximum distance. Reflectance readings were carried out for the soybean crop with a radiometer GreenSeeker®, considering basic units of 0.45 m² in an area of ten rows, 10 m long, for each treatment. Treatments were applied to create a gradient of Asian soybean rust, varying the number of fungicide applications. Data were collected in two phenological stages (R5.5 and R6), obtaining 300 simulations of experimental area for each stage. Based on the results, the use of 5.40 m² plots with a group of three rows, 4 m long, is recommended.

Keywords
NDVI; Maximum distance; Modified maximum curvature

Number of sprays		Spraying (days after germination)
6		30, 45, 60, 75, 90, 105
4		60, 75, 90, 105
3		75, 90, 105
0		-

Simulation	Width	Length	L×W	Size (m²)	Type of Grouping	Number of plots
1	1	1	1	0.45	0.45 x 1.00	100
2	2	1	2	0.90	0.90 x 1.00	50
3	3	1	3	1.35	1.35 x 1.00	30
4	4	1	4	1.80	1.80 x 1.00	20
5	5	1	5	2.25	2.25 x 1.00	20
6	6	1	6	2.70	2.70 x 1.00	10
7	7	1	7	3.15	3.15 x 1.00	10
8	8	1	8	3.60	3.60 x 1.00	10
9	9	1	9	4.05	4.05 x 1.00	10
10	10	1	10	4.50	4.50 x 1.00	10
11	1	2	2	0.90	0.45 x 2.00	50
12	1	3	3	1.35	0.45 x 3.00	30
13	1	4	4	1.80	0.45 x 4.00	20
14	1	5	5	2.25	0.45 x 5.00	20
15	1	6	6	2.70	0.45 x 6.00	10
16	1	7	7	3.15	0.45 x 7.00	10
17	1	8	8	3.60	0.45 x 8.00	10
18	1	9	9	4.05	0.45 x 9.00	10
19	1	10	10	4.50	0.45 x 10.00	10
20	2	2	4	1.80	0.90 x 2.00	25
21	3	2	6	2.70	1.35 x 2.00	15
22	4	2	8	3.60	1.80 x 2.00	10
23	5	2	10	4.50	2.25 x 2.00	10
24	6	2	12	5.40	2.70 x 2.00	5
25	7	2	14	6.30	3.15 x 2.00	5
26	8	2	16	7.20	3.69 x 2.00	5
27	9	2	18	8.10	4.05 x 2.00	5
28	10	2	20	9.00	4.50 x 2.00	5
29	2	3	6	2.70	0.90 x 3.00	15
30	3	3	9	4.05	1.35 x 3.00	9
31	4	3	12	5.40	1.80 x 3.00	6
32	5	3	15	6.75	2.25 x 3.00	6
33	6	3	18	8.10	2.70 x 3.00	3
34	7	3	21	9.45	3.15 x 3.00	3
35	8	3	24	10.80	3.60 x 3.00	3
36	9	3	27	12.15	4.05 x 3.00	3
37	10	3	30	13.50	4.50 x 3.00	3
38	2	4	8	3.60	0.90 x 4.00	10
39	3	4	12	5.40	1.35 x 4.00	6
40	4	4	16	7.20	1.80 x 4.00	4
41	5	4	20	9.00	2.25 x 4.00	4
42	6	4	24	10.80	2.70 x 4.00	2
43	7	4	28	12.60	3.15 x 4.00	2
44	8	4	32	14.40	3.60 x 4.00	2
45	9	4	36	16.20	4.05 x 4.00	2
46	10	4	40	18.00	4.50 x 4.00	2
47	2	5	10	4.50	0.90 x 5.00	10
48	3	5	15	6.75	1.35 x 5.00	6
49	4	5	20	9.00	1.80 x 5.00	4
50	5	5	25	11.25	2.25 x 5.00	4
51	6	5	30	13.50	2.70 x 5.00	2
52	7	5	35	15.75	3.15 x 5.00	2
53	8	5	40	18.00	3.60 x 5.00	2
54	9	5	45	20.25	4.05 x 5.00	2
55	10	5	50	22.50	4.50 x 5.00	2
56	2	6	12	5.40	0.90 x 6.00	5
57	3	6	18	8.10	1.35 x 6.00	3
58	4	6	24	10.80	1.80 x 6.00	2
59	5	6	30	13.50	2.25 x 6.00	2
60	2	7	14	6.30	0.90 x 7.00	5
61	3	7	21	9.45	1.35 x 7.00	3
62	4	7	28	12.60	1.80 x 7.00	2
63	5	7	35	15.75	2.25 x 7.00	2
64	2	8	16	7.20	0.90 x 8.00	5
65	3	8	24	10.80	1.35 x 8.00	3
66	4	8	32	14.40	1.80 x 8.00	2
67	5	8	40	18.00	2.25 x 8.00	2
68	2	9	18	8.10	0.90 x 9.00	5
69	3	9	27	12.15	1.35 x 9.00	3
70	4	9	36	16.20	1.80 x 9.00	2
71	5	9	45	20.25	2.25 x 9.00	2
72	2	10	20	9.00	0.90 x 10.00	5
73	3	10	30	13.50	1.35 x 10.00	3
74	4	10	40	18.00	1.80 x 10.00	2
75	5	10	50	22.50	2.25 x 10.00	2

Number of Sprays	R5.5	R6
6	0.678c	0.319a
4	0.639c	0.346b
3	0.480b	0.354b
0	0.370a	0.288a

Treatment	Stage	Simulation	a	B	C	d	E	R²
6 Sprays	R5.5	75	2.6344	0.522	-0.0481	2.6825	20.790	0.375
		50	2.3295	0.458	-0.0844	2.4139	11.848	0.503
		25	2.0661	0.388	-0.1749	2.3815	5.717	0.617
	R6	75	12.615	0.653	-0.2421	12.857	4.130	0.255
		50	9.511	0.506	-0.3564	9.868	2.805	0.399
		25	8.027	0.400	-0.6491	8.676	1.540	0.404
4 Sprays	R5.5	75	2.151	0.381	-0.0354	2.186	28.248	0.412
		50	2.335	0.428	-0.0893	2.424	11.198	0.541
		25	2.395	0.459	-0.2054	2.601	4.8685	0.744
	R6	75	12.615	0.653	-0.2421	12.857	4.130	0.255
		50	9.512	0.506	-0.3564	9.868	2.805	0.399
		25	8.027	0.400	-0.6491	8.676	1.541	0.404
3 Sprays	R5.5	75	2.528	0.810	-0.0500	2.578	20.000	0.408
		50	1.950	0.664	-0.0785	2.028	12.738	0.565
		25	1.511	0.503	-0.1585	1.669	6.309	0.896
	R6	75	9.960	0.418	-0.1698	10.130	5.889	0.385
		50	8.339	0.321	-0.2593	8.598	3.856	0.371
		25	8.471	0.336	-0.6221	9.092	1.607	0.384
No Sprays	R5.5	75	3.320	0.506	-0.0576	3.377	17.361	0.439
		50	2.678	0.390	-0.0911	2.769	10.976	0.684
		25	2.848	0.430	-0.2884	3.467	3.467	0.754
	R6	75	13.764	0.432	-0.2374	14.001	4.212	0.216
		50	12.031	0.377	-0.3745	11.980	2.670	0.370
		25	13.641	0.473	-1.1476	14.789	0.871	0.440

Treatment	Simulation	MMC	MD
6 sprays	75 – R5.5	LxW=1 (0.45m²)	LxW=10 (4.50m²)
	50 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	75 – R6	LxW=1 (0.45m²)	LxW=8 (3.60m²)
	50 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R6	LxW=1 (0.45m²)	LxW=5 (2.25m²)
4 sprays	75 – R5.5	LxW=1 (0.45m²)	LxW=8 (3.60m²)
	50 – R5.5	LxW=1 (0.45m²)	LxW=5 (2.25m²)
	25 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	75 – R6	LxW=1 (0.45m²)	LxW=10 (4.50m²)
	50 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
3 sprays	75 – R5.5	LxW=1 (0.45m²)	LxW=9 (4.05m²)
	50 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	75 – R6	LxW=1 (0.45m²)	LxW=9 (4.05m²)
	50 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
No sprays	75 – R5.5	LxW=1 (0.45m²)	LxW=9 (4.05m²)
	50 – R5.5	LxW=1 (0.45m²)	LxW=10 (4.50m²)
	25 – R5.5	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	75 – R6	LxW=1 (0.45m²)	LxW=9 (4.05m²)
	50 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)
	25 – R6	LxW=1 (0.45m²)	LxW=4 (1.80m²)

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[1] Corresponding Author: Roger Nabeyama Michels (rogernmichels@utfpr.edu.br)