Controlled Release of TBH Herbicide Encapsulated on Ca-ALG Microparticles: Leaching and Phytointoxication Plants

MACEDO, D.F.; DOURADO JR., S.M.; NUNES, E.S.; MARQUES, R.P.; MORETO, J.A.

doi:10.1590/S0100-83582019370100067

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Article • Planta daninha 37 • 2019 • https://doi.org/10.1590/S0100-83582019370100067 copy

Controlled Release of TBH Herbicide Encapsulated on Ca-ALG Microparticles: Leaching and Phytointoxication Plants

Liberação Controlada do Herbicida TBH Encapsulado em Micropartículas de ALG-Ca: Lixiviação e Fitointoxicação de plantas

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT:

The aim of this work was to demonstrate a detailed study of the controlled release of the herbicide Tebuthiuron (TBH) encapsulated in microparticles of calcium alginate (Ca-ALG), to evaluate the phytotoxicity in different concentrations of herbicide (4, 6 and 8 g L-1), and their correlation with the depth of leaching using bioindicator plants. The Ca-ALG microparticles were prepared from the crosslinking of sodium alginate by Ca++ containing varied amounts of TBH supplied in calcium chloride (CaCl2) aqueous solution. The results showed that TBH herbicide, when encapsulated, leached to shallow depths relative to the conventional, non-encapsulated herbicide (which moved to a depth of 40-50 cm). The concentration of 4 g L-1 was the one that leached most in the PVC columns, but its mobility did not exceed 30 cm of depth. The results of the dry mass corroborated with the phytotoxicity results of the bioindicator plants, evidencing the mobility of the conventional herbicide in the soil at depths around 40 and 50 cm, while the herbicide encapsulated in the Ca-ALG microparticles did not show leaching beyond 20 -30 cm deep. The encapsulation of TBH in Ca-ALG microparticles can thus be considered as a more eco-friendly technology, reducing the leaching process and consequently soil contamination.

Keywords:
pesticides; biodegradable polymer; environmental impact; encapsulation; agriculture

Sociedade Brasileira da Ciência das Plantas Daninhas Departamento de Fitotecnia - DFT, Universidade Federal de Viçosa - UFV, 36570-000 - Viçosa-MG - Brasil, Tel./Fax::(+55 31) 3899-2611 - Viçosa - MG - Brazil
E-mail: rpdaninha@gmail.com

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[1] * Corresponding author: <renata.marques@ifgoiano.edu.br>

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	70.00 b	91.67 c	98.33 c
4 g L^-1	-	1.67 a	13.33 b	40.00 b
6 g L^-1	-	0.00 a	9.00 ab	21.67 a
8 g L^-1	-	0.00 a	1.67 a	9.00 a
F Treatment	-	173.70**	272.80**	156.42**
MSD	-	11.94	11.55	14.31
CV%	-	25.48	15.27	12.95
Default Error	-	2.64	2.55	3.16

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	73.33 b	91.66 b	96.66 c
4 g L^-1	-	0.00 a	8.33 a	10.00 b
6 g L^-1	-	0.00 a	4.66 a	7.66 a
8 g L^-1	-	0.00 a	0.00 a	7.33 a
F Treatment	-	21.275**	98.80**	509.24**
MSD	-	36.03	19.96	8.87
CV%	-	75.10	29.17	11.15
Default Error	-	7.94	4.40	1.95

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	36.66 b	36.67 b	48.33 b
4 g L^-1	-	0.00 a	0.00 a	0.00 a
6 g L^-1	-	0.00 a	0.00 a	0.00 a
8 g L^-1	-	0.00 a	0.00 a	0.00 a
F Treatment	-	121.00**	69.14**	11.53**
MSD	-	7.56	9.99	32.27
CV%	-	31.49	41.66	102.06
Default Error	-	1.67	2.21	7.12

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	21.67 b	20.00 a	16.67 b
4 g L^-1	-	0.00 a	0.00 a	0.00 a
6 g L^-1	-	0.00 a	0.00 a	0.00 a
8 g L^-1	-	0.00 a	0.00 a	0.00 a
F Treatment	-	8.89**	3.00^ns	5.26*
MSD	-	16.47	26.17	16.47
CV%	-	116.15	200.00	151
Default Error	-	3.64	5.78	3.64

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	5.00 a	6.67 a	8.33 a
4 g L^-1	-	0.00 a	0.00 a	0.00 a
6 g L^-1	-	0.00 a	0.00 a	0.00 a
8 g L^-1	-	0.00 a	0.00 a	0.00 a
F Treatment	-	1.00^ns	1.00^ns	8.33^ns
MSD	-	11.33	15.11	18.89
CV%	-	346.41	346.41	346.41
Default Error	-	2.5	3.34	4.17

Depth (cm)	Control	Conventional	4 g L^-1	6 g L^-1	8 g L^-1
Depth (cm)	(g)
10	0.18 Aa	0.00 Bb	0.05 Ab	0.14 Aa	0.17 Aa
20	0.09 Bab	0.00 Bc	0.33 Abc	0.07 Aabc	0.12 Aba
30	0.08 Ba	0.04 Aba	0.05 Aa	0.95 Aa	0.07 Ba
40	0.12 Ba	0.09 Aa	0.11 Aa	0.08 Aa	0.08 Ba
50	0.13 Ba	0.99 Aa	0.11 Aa	0.08 Aa	0.09 Ba
Blocks	2	0.00	0.00
Depth	4	0.05	0.013	3.18
Treatment	4	0.025	0.01	1.52
Depth x Treatment	16	0.06	0.00	3.17
Residue	48	0.00	0.00
CV%	40.95

Treatment	Days after sowing
Treatment	14	21	28	35
Control	-	-	-	-
Conventional	-	51.67 b	90.00 c	98.33 c
4 g L^-1	10.00 a	10.00 a	20.00 b	58.33 b
6 g L^-1	15.00 b	12.00 a	15.00 ab	35.00 a
8 g L^-1	20.00 c	15.00 a	9.00 a	28.33 a
F Treatment	1.009**	23.53**	325.82**	120.00**
MSD	4.67	18.48	9.53	13.08
CV%	0.00	31.85	10.87	9.09
Default Error	0.00	4.07	2.11	2.89

Depth (cm)	Control	Conventional	4 g L^-1	6 g L^-1	8 g L^-1
Depth (cm)	(g)
10	2.34 Aa	0.20 Bc	0.97 CDb	2.08 Aa	2.26 Aba
20	1.91 Aba	0.23 Bb	0.62 Db	1.76 Aa	2.38 Aa
30	1.60 Bab	1.15 Ab	1.41 BCab	1.91 Aa	1.59 Bab
40	2.02 ABa	1.57 Aa	1.75 Ba	1.85 Aa	1.98 Aba
50	2.17 Bab	1.61 Ab	2.55 Aa	1.78 Ab	2.13 ABab
Blocks	2	0.96	0.48
Depth	4	13.14	3.28	4.99
Treatment	4	4.19	1.05	1.59
Depth x Treatment	16	10.53	0.66	6.60
Residue	48	4.78	0.10
CV%	18.87