Integrated management of aflatoxin B₁ contamination of groundnut (Arachis hypogaea L.) with Burkholderia sp. and zimmu (Allium sativum L.×Allium cepa L.) intercropping

Figures & data

Table 1 In vitro antagonistic activity of Burkholderia sp. strain TNAU-1 against aflatoxigenic and non-aflatoxigenic isolates of Aspergillus flavus.

S. No.	Isolate	Toxigenicity	Inhibition zone (mm)
1	AFG 1	Toxigenic	11.3^a
2	AFG 13	Non-toxigenic	4.8^jk
3	AFG 15	Non-toxigenic	5.0^ij
4	AFG 17	Non-toxigenic	8.2^d
5	AFG 19	Non-toxigenic	7.4^e
6	AFG 20	Non-toxigenic	9.6^b
7	AFG 21	Toxigenic	6.1^g
8	AFG 23	Non-toxigenic	5.6^h
9	AFG 24	Non-toxigenic	6.7^f
10	AFG 29	Toxigenic	3.8^l
11	AFG 32	Toxigenic	4.8^jk
12	AFG 40	Toxigenic	7.2^e
13	AFG 43	Non-toxigenic	8.9^c
14	AFG 46	Toxigenic	5.3^hi
15	AFG 47	Toxigenic	3.1^m
16	AFG 48	Non-toxigenic	4.4^k
17	AFG 49	Toxigenic	4.9^ij
18	AFG 52	Non-toxigenic	6.2^g
Data are mean of three replications; Means followed by the same letter in a column are not significantly different (p=0.05) by Duncan's Multiple Range Test (DMRT).

Table 2. Population of Burkholderia sp. strain TNAU-1 in the talc-based powder formulation.

Days after preparation	Population of Burkholderia sp. strain TNAU-1 (×10^8 CFU/g)
0	15.9^a
30	8.8^b
60	3.2^c
90	0.1^d
Data are mean of four replications; Means followed by the same letter in a column are not significantly different (p=0.05) by DMRT.

Table 3. Effect of seed bacterization with the formulation of Burkholderia sp. strain TNAU-1 on seed germination and seedling vigor of groundnut (cv. CO-3).

Treatment	Germination (%)	Shoot length (cm)	Root length (cm)	Vigor index
Treated	96.4 (81.1)^a	9.9^a	18.3^a	2712.0
Untreated control	87.1 (69.0)^b	8.6^b	14.1^b	1856.7
Data are mean of eight replications; Figures in parentheses are arcsine transformed values; Data followed by the same letter in a column are not significantly different (p=0.05) from each other according to DMRT.

Table 4. Effect of seed treatment or soil application with the formulation of Burkholderia sp. strain TNAU-1 or intercropping with zimmu on Aspergillus flavus infection, aflatoxin B₁ concentration, oil content and pod yield of groundnut (cv. VRI-2) under field conditions (Trial I).

Treatment	A. flavus infection (%)	Aflatoxin B1 content ( g/kg)	Oil content%	100 seed wt (g)	Pod yield (kg/ha)
Zimmu intercropping	0 (0.6)	1.6^a	42.1^a	41.4^c	1596.6^e
Seed treatment with Burkholderia sp. (10 g/kg)	5 (13.3)	3.8^a	42.5^a	41.4^c	1731.6^b
Soil application with Burkholderia sp. (2.5 kg/ha on 30, 45, 60 DAS)	10 (18.3)	5.6^a	42.3^a	41.3^c	1815.0^a
Seed treatment + soil application with Burkholderia sp.	10 (18.3)	3.2^a	42.9^a	41.8^b	1821.6^a
Seed treatment + soil application with Burkholderia sp.+Zimmu intercropping	0 (0.6)	0.6^a	42.4^a	42.2^a	1660.0^d
Seed treatment with carbendazim (2 g/kg seed)	50 (45.0)	31.5^b	42.3^a	41.8^b	1696.6^c
Untreated control	65 (53.9)	71.4^c	42.3^a	41.4^c	1255.0^f
Zimmu was intercropped once in every three rows of groundnut, one week prior to sowing of groundnut. Powder formulation of Burkholderia sp. strain TNAU-1 was applied as seed treatment (10 g/kg seed) or soil application (2.5 kg/ha on 30, 45, 60 DAS) or as seed treatment followed by soil application. Figures in parentheses are arcsine transformed values. The data are mean of three replications. Means within a column followed by a common letter are not significantly different (p=0.05) by DMRT.

Table 5. Effect of seed treatment or soil application with the formulation of Burkholderia sp. strain TNAU-1 or intercropping with zimmu on Aspergillus flavus infection, aflatoxin B₁ concentration, oil content and pod yield of groundnut (cv. CO-3) under field conditions (Trial II).

Treatment	A. flavus infection (%)	Aflatoxin B1 content ( g/kg)	Oil content%	100 seed wt (g)	Pod yield (kg/ha)
Zimmu intercropping	2 (7.9)	3.0^a	42.4^a	39.2^a	2625.0^c
Seed treatment with Burkholderia sp. (10 g/kg)	10 (18.4)	4.2^a	42.2^a	39.2^a	3128.3^ab
Soil application with Burkholderia sp. (2.5 kg/ha on 30, 45, 60 DAS)	20 (26.5)	8.7^a	43.6^a	39.2^a	3150.0^ab
Seed treatment + soil application with Burkholderia sp.	15 (23.0)	5.8^a	41.4^a	39.0^a	3223.3^a
Seed treatment + soil application with Burkholderia sp.+Zimmu intercropping	2 (7.9)	2.9^a	43.2^a	39.3^a	2801.6^bc
Seed treatment with carbendazim (2 g/kg seed)	55 (48.1)	29.1^b	43.6^a	39.1^a	3015.0^ab
Untreated control	65 (53.9)	92.4^c	41.5^a	38.9^a	2975.0^ab
Zimmu was intercropped once in every three rows of groundnut, one week prior to sowing of groundnut. Powder formulation of Burkholderia sp. strain TNAU-1 was applied as seed treatment (10 g/kg seed) or soil application (2.5 kg/ha on 30, 45, 60 DAS) or as seed treatment followed by soil application. Figures in parentheses are arcsine transformed values. The data are mean of three replications. Means within a column followed by a common letter are not significantly different (p=0.05) by DMRT.

Table 6. Population of A. flavus and Burkholderia sp. in rhizosphere soils sampled at different time intervals after treatment (Trial I).

	Population (×10^3 CFU/g soil)
	60 DAS		110 DAS
Treatment	Burkholderia sp.	A. flavus	Burkholderia sp.	A. flavus
Zimmu intercropping	0^a	0^a	0^a	0^a
Seed treatment with Burkholderia sp.	109^d	0^a	138^d	0^a
Soil application with Burkholderia sp.	143^c	0^a	151^c	0^a
Seed + soil application with Burkholderia sp.	156^b	0^a	158^bc	0^a
Seed treatment + soil application with Burkholderia sp.+Zimmu intercropping	154^b	0^a	162^b	0^a
Seed treatment with carbendazim	0^a	5^b	0^a	6^c
Untreated control	0^a	13^c	0^a	15^c
Initial population of A. flavus at the time of planting was 2×10^3/g soil. Data are mean of three replications. Data followed by the same letter in a column are not significantly different (p=0.05) by DMRT.

Table 7. Population of A. flavus and Burkholderia sp. in rhizosphere soils sampled at different time intervals after treatment (Trial II).

	Population (×10^3 CFU/g soil)
	60 DAS		110 DAS
Treatment	Burkholderia sp.	A. flavus	Burkholderia sp.	A. flavus
Zimmu intercropping	0^a	0^a	0^a	0^a
Seed treatment with Burkholderia sp.	81^d	0^a	101^d	0^a
Soil application with Burkholderia sp.	105^c	0^a	134^c	0^a
Seed + soil application with Burkholderia sp.	113^b	0^a	154^b	0^a
Seed treatment + soil application with Burkholderia sp.+Zimmu intercropping	103^c	0^a	153^b	0^a
Seed treatment with carbendazim	0^a	2^b	0^a	3^b
Untreated control	0^a	6^c	0^a	6^c
Initial population of A. flavus at the time of planting was 1.1×10^3/g soil. Data are mean of three replications. Data followed by the same letter in a column are not significantly different (p=0.05) by DMRT.

Figure 1.  Detection of Burkholderia sp. by polymerase chain reaction. Lane 1, DNA ladder; Lanes 2–7, Burkholderia sp. strain TNAU-1 colonies from the experimental field; Lane 8, Xanthomonas oryzae pv. oryzae; Lane 9, Pseudomonas fluorescens; Lane 10, Bacillus subtilis; Lane 11, Azospirillum brasiliense; Lane 12, Purified DNA from Burkholderia sp. strain TNAU-1.