Methods to quantify <i>Bacillus simplex</i>-based inoculant and its effect as a seed treatment on field-grown corn and soybean in Brazil

Senger, Marina; Moresco, Eloir; Dalbosco, Marisa; Santin, Rita; Inderbitzin, Patrik; Barrocas, Ellen Noly

doi:10.1590/2317-1545v44263329

Abstract:

Growth-promoting bacteria in agriculture have become an important tool to improve crop performance and productivity in the face of climate change and deteriorating soil conditions. Bacillus simplex is a recently developed active ingredient for the growth promotion of corn and soybean in Brazil. This study compared three methods to quantify B. simplex colony-forming units in the inoculant product and evaluated the treatment effects of four different concentrations of a B. simplex-based inoculant on corn and soybean root and shoot dry weight, the Normalized Difference Vegetation Index (NDVI), and yield. Field trials were performed at four different locations for each crop, in Mato Grosso do Sul and Paraná for corn, and in Mato Grosso do Sul, Minas Gerais, and Paraná for soybean. The performance of B. simplex was compared to an Azospirillum brasilense-based inoculant, a polymer seed treatment, and untreated controls. The results showed that the official MAPA method for quantifying microbes in inoculants recovered the highest number of B. simplex colonies. However, all three evaluated quantification methods recovered over 100 million colony-forming units per mL (10⁸ CFU.mL^-1). The field results showed that the B. simplex inoculant generally increased corn and soybean yields as much or more as the A. brasilense product and that the polymer seed treatment had no impact on yield. The treatment effect on root and shoot weight, and NDVI, was inconsistent. This research shows that B. simplex is quantifiable with three different methods and that it can improve yield in corn and soy. The Bacillus simplex-based inoculant has the potential to become widely used in Brazil.

Index terms:
bioinputs; biological product; inoculant; plant growth-promoting; seed treatment.

[1] *Corresponding author
E-mail: marina.senger@estacaoexperimental3m.com.br

Crop	Hybrid/Varieties- Company	Germination/Purity (%)	Locality/State	Geographical coordinates/Climate (Köppen)	Type of soil
Corn	Status Viptera- Syngenta	99/100	Ponta Grossa - Paraná (PR)	25°10’11.61” S, 51°11′17.22” E/ Oceanic climate (Cfb)	Sandy clay loam
Corn	Supremo Viptera- Syngenta	97/100	Imbituva - Paraná (PR)	25°9’23.41” S, 50°32′57.68” E/ Oceanic climate (Cfb)	Sandy clay
Corn	Supremo Viptera- Syngenta	97/100	Lapa - Paraná (PR)	25°44’30.72” S, 49°48′16.91” E/ Oceanic climate (Cfb)	Sandy clay loam
Corn	Supremo Viptera- Syngenta	97/100	Dourados - Mato Grosso do Sul (MS)	22°05’23.08” S, 55°08′22.27” E/ Tropical monsoon climate (Am)	Clay
Soybean	Brasmax Garra IPRO- Brasmax	98/100	Imbituva - Paraná (PR)	25°9’20.13” S, 50°32′57.09” E/ Oceanic climate (Cfb)	Sandy clay
Soybean	Brasmax Garra IPRO- Brasmax	98/100	Uberlândia - Minas Gerais (MG)	19°2’24.21” S, 48°11′50.83” E/ Tropical savana climate (Aw)	Clay
Soybean	Monsoy 5947 IPRO- Bayer	95/100	Lapa - Paraná (PR)	25°44’33.62” S, 49°48′19.62” E/ Oceanic climate (Cfb)	Sandy clay loam
Soybean	Monsoy 5947 IPRO- Bayer	95/100	Dourados - Mato Grosso do Sul (MS)	22°05’24.69” S, 55°08′24.23” E/ Tropical monsoon climate (Am)	Clay

Localities	Chemical Analysis									Granulometry
	P	MO	pH	H+Al	Al	K	Ca	Mg	CTC	Clay	Silt	Sand
	(mg.m^-3)	(g.dm^-3)	(CaCl₂)	(mmolc.dm^-3)						(g.kg^-1)
Ponta Grossa - PR	52	48	4.8	86	0.6	7.2	53	17	163	351	188	461
Imbituva - PR	43	37	6.2	13	N.D	1.8	115	21	151	390	66	544
Lapa - PR	17	36	4.6	65	3.7	4.1	18	8	95	230	156	614
Dourados - MS	59	26	5.0	38	N.D	7.4	34	13	92	584	125	291
Uberlândia - MG	31	23	5.0	30	N.D	3.8	21	8	63	499	157	344

Treatment ^a a Means (n = 4) followed by different letters on the same column are significantly different (p ≤ 0.05, Scott-Knott test). Legend: Ab=Azospirillum brasilense, Bs=Bacillus simplex, CV=coefficient of variation.	Status								Supremo
	Ponta Grossa								Imbituva
	Root dry weight		Shoot dry weight		NDVI		Yield		Root dry weight		Shoot dry weight		NDVI		Yield
	(g)		(g)		(N)		(kg.ha^-1)		(g)		(g)		(N)		(kg.ha^-1)
Non-inoculated	148	a	263	b	76	a	8028	b	2228	a	248	b	81	a	5865	b
Non-inoculated + Polymer	185	a	217	b	77	a	8230	b	188	b	202	b	82	a	5635	b
Ab 2x10⁸ CFU.mL^-1	231	a	285	b	80	a	9178	a	3149	a	350	a	81	a	6463	a
Bs 5x10⁴ CFU.mL^-1	200	a	287	b	77	a	7981	b	239	a	263	b	82	a	7224	a
Bs 5x10⁵ CFU.mL^-1	142	a	351	a	77	a	10136	a	145	b	251	b	82	a	6582	a
Bs 5x10⁶ CFU.mL^-1	161	a	314	a	77	a	9644	a	245	a	263	b	82	a	6927	a
Bs 5x10⁷ CFU.mL^-1	183	a	275	b	79	a	8978	a	245	a	290	b	83	a	7028	a
CV (%)	29		14		3		7		23		12		2		12

Treatment ^a a Means (n = 4) followed by different letters on the same column are significantly different (p ≤ 0.05, Scott-Knott test). Legend: Ab=Azospirillum brasilense, Bs=Bacillus simplex, CV=coefficient of variation.	Supremo								Supremo
	Lapa								Dourados
	Root dry weight		Shoot dry weight		NDVI		Yield		Root dry weight		Shoot dry weight		NDVI		Yield
	(g)		(g)		(N)		(kg.ha^-1)		(g)		(g)		(N)		(kg.ha^-1)
Non-inoculated	230	a	253	a	81	b	5979	b	109	b	109	b	80	d	7312	b
Non-inoculated + Polymer	222	a	231	a	82	b	6214	b	110	b	111	b	80	d	6964	b
Ab 2x10⁸ CFU.mL^-1	226	a	258	a	84	a	6827	a	131	a	124	b	83	c	6906	b
Bs 5x10⁴ CFU.mL^-1	231	a	258	a	83	a	7399	a	112	b	109	b	84	b	6296	b
Bs 5x10⁵ CFU.mL^-1	257	a	268	a	83	a	6436	b	121	b	125	b	83	b	7556	b
Bs 5x10⁶ CFU.mL^-1	250	a	278	a	84	a	6792	a	145	a	121	b	85	a	7299	b
Bs 5x10⁷ CFU.mL^-1	276	a	287	a	84	a	7284	a	151	a	144	a	85	a	9043	a
CV (%)	15		11		1		7		10		9		1		10

Treatment ^a a Means (n = 4) followed by different letters on the same column are significantly different (p ≤ 0.05, Scott-Knott test). Legend: Ab=Azospirillum brasilense, Bs=Bacillus simplex, CV=coefficient of variation.	BMX								BMX
	Imbituva								Uberlândia
	Root dry weight		Shoot dry weight		NDVI		Yield		Root dry weight		Shoot dry weight		NDVI		Yield
	(g)		(g)		(N)		(kg.ha^-1)		(g)		(g)		(N)		(kg.ha^-1)
Non-inoculated	3	a	31	a	81	c	2562	b	4	a	30	a	83	a	2643	b
Non-inoculated + Polymer	3	a	31	a	79	d	2351	b	4	a	31	a	82	a	2717	b
Ab 2x10⁸ CFU.mL^-1	2	a	33	a	81	c	2581	b	3	a	26	a	82	a	2655	b
Bs 1x10⁴ CFU.mL^-1	3	a	36	a	79	d	2528	b	4	a	30	a	83	a	2946	a
Bs 1x10⁵ CFU.mL^-1	3	a	40	a	84	b	2859	a	4	a	30	a	84	a	3079	a
Bs 1x10⁶ CFU.mL^-1	3	a	37	a	86	a	2832	a	4	a	31	a	82	a	2933	a
Bs 1x10⁷ CFU.mL^-1	3	a	35	a	86	a	2985	a	4	a	31	a	83	a	2846	a
CV (%)	15		17		1		11		18		16		1		7

Brasil

Brasil

Methods to quantify Bacillus simplex-based inoculant and its effect as a seed treatment on field-grown corn and soybean in Brazil

Abstract:

Treatment ^a a Means (n = 4) followed by different letters on the same column are significantly different (p ≤ 0.05, Scott-Knott test). Legend: Ab=Azospirillum brasilense, Bs=Bacillus simplex, CV=coefficient of variation.	Monsoy								Monsoy
	Lapa								Dourados
	Root dry weight		Shoot dry weight		NDVI		Yield		Root dry weight		Shoot dry weight		NDVI		Yield
	(g)		(g)		(N)		(kg.ha^-1)		(g)		(g)		(N)		(kg ha^-1)
Non-inoculated	3	a	38	a	85	b	2317	b	4	a	5	b	72	d	1306	a
Non-inoculated + Polymer	3	a	29	a	85	b	2291	b	4	a	5	b	73	c	1315	a
Ab 2x10⁸ CFU.mL^-1	3	a	38	a	88	a	2677	a	4	a	6	b	74	c	1193	a
Bs 1x10⁴ CFU.mL^-1	3	a	31	a	87	a	2819	a	4	a	7	a	75	b	1373	a
Bs 1x10⁵ CFU.mL^-1	3	a	43	a	87	a	2660	a	4	a	7	a	75	b	1363	a
Bs 1x10⁶ CFU.mL^-1	3	a	33	a	87	a	2684	a	4	a	7	a	76	a	1419	a
Bs 1x10⁷ CFU.mL^-1	3	a	43	a	88	a	2665	a	5	a	8	a	78	a	1431	a
CV (%)	12		20		1		9		17		6		1		8