Effects of Grass-Based Crop Rotation, Nematicide, and Irrigation on the Nematode Community in Cotton

Index name	Abbreviation	c-p nematodes^a	Indication (high value)^b
Maturity	MI	1–5	Stable/enriched environment
Enrichment	EI	1–2	Enriched environment
Structure	SI	3–5	High food web complexity
Channel	CI	1–2	Fungal-dominated decomposition
Basal	BI	2	Stressed/degraded environment

[i] ^aBased on weighted proportions of colonizer-persister series included in calculation of index (Bongers and Bongers, 1998).

bHigh value as an indication of environmental status (Ferris et al., 2001).

BI, Basal Index; CI, Channel Index; EI, Enrichment Index; MI, Maturity Index; SI, Structure Index.

Table 2

Effects of irrigation, crop phase, and nematicide application on fungivore population density in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	189a	150	131	236	172	256
Rainfed	103b	140	142	254	176	240
Crop phase^y
CS	224A	178	79B	286	153	220
C1	104B	129	81B	221	182	244
C2	110B	129	249A	228	186	281
Nematicide
Without fluopyram	147	141	132	259	140	270
With fluopyram	144	149	141	231	208	226
ANOVA (P-values)
Irrigation (I)	0.04*	0.85	0.20	0.42	0.91	0.51
Crop (C)	0.02*	0.33	<0.01**	0.50	0.75	0.84
I × C	0.48	0.26	0.45	0.32	0.63	0.96
Nematicide (N)	0.94	0.66	0.75	0.38	0.08	0.11
I × N	0.77	0.14	0.71	0.43	0.40	0.13
C × N	0.93	<0.01**	0.86	0.79	0.64	0.37
I × C × N	0.95	0.06	0.44	0.68	0.86	0.85

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^xPi, Pm, and Pf are mean nematode population densities (per 100 cm³ soil) prior to planting, at midseason (52 d and 56 d after planting in 2017 and 2018), and at harvest (150 d and 151 d after planting in 2017 and 2018), respectively.

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

LSD, least significant difference.

Table 3

Effects of irrigation, crop phase, and nematicide application on bacterivore population density in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	730	387	151	726	525	314
Rainfed	602	430	196	898	608	516
Crop phase^y
CS	798	431	84B	824	518	355
C1	692	333	70B	808	505	432
C2	507	461	367A	804	675	458
Nematicide
Without fluopyram	718	433	176	828	538	414
With fluopyram	614	383	172	797	595	416
ANOVA (P-values)
Irrigation (I)	0.35	0.41	0.23	0.37	0.23	0.13
Crop (C)	0.39	0.34	<0.01**	0.99	0.55	0.72
I × C	0.78	0.15	0.23	0.36	0.27	0.31
Nematicide (N)	0.14	0.27	0.93	0.80	0.55	0.98
I × N	0.21	0.67	0.79	0.29	0.86	0.13
C × N	0.31	0.02*	0.62	0.94	0.36	0.03
I × C × N	0.07	0.90	0.38	0.71	0.24	0.51

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

LSD, least significant difference.

Table 4

Effects of irrigation, crop phase, and nematicide application on omnivore population density in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	19	76a	18	55	58	58
Rainfed	14	60b	12	64	50	45
Crop phase^y
CS	22	58	23	44	63	25
C1	22	84	9	73	38	59
C2	5	62	13	62	61	69
Nematicide
Without fluopyram	17	87	17	80a	71a	84a
With fluopyram	15	48	13	39b	37b	19b
ANOVA (P-values)
Irrigation (I)	0.59	0.04*	0.30	0.86	0.45	0.11
Crop (C)	0.18	0.67	0.17	0.63	0.59	0.53
I × C	0.40	0.97	0.63	0.35	0.73	0.91
Nematicide (N)	0.72	0.07	0.40	0.04*	<0.01**	<0.01**
I × N	0.12	0.74	0.06	0.66	0.25	0.74
C × N	0.66	0.38	0.27	0.18	0.43	<0.01**
I × C × N	0.02	0.48	0.70	0.61	0.97	0.43

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^xPi, Pm, and Pf are mean values of nematode ecological indices prior to planting, at midseason (52 d and 56 d after planting in 2017 and 2018), and at harvest (150 d and 151 d after planting in 2017 and 2018), respectively.

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

MI, Maturity Index; LSD, least significant difference.

Table 5

Effects of irrigation, crop phase, and nematicide application on BI in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	30	28b	38	35	37	36
Rainfed	26	33a	43	42	42	43
Crop phase^y
CS	22B	25	32	37	35	41
C1	21B	28	40	35	38	40
C2	41A	38	50	44	46	37
Nematicide
Without fluopyram	25	30	38	36	39	37
With fluopyram	31	30	44	41	40	42
ANOVA (P-values)
Irrigation (I)	0.32	0.05*	0.62	0.28	0.31	0.44
Crop (C)	0.03*	0.11	0.16	0.40	0.30	0.85
I × C	0.66	0.85	0.66	0.22	0.90	0.98
Nematicide (N)	0.15	0.98	0.29	0.25	0.84	0.34
I × N	0.69	0.87	0.15	0.66	0.70	0.30
C × N	0.24	0.29	0.06	0.92	0.01**	0.24
I × C × N	0.35	0.55	0.46	0.37	0.65	0.84

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

LSD, least significant difference; BI, Basal Index.

Table 6

Effects of irrigation, crop phase, and nematicide application on EI in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	66	56	46	53	46	48
Rainfed	71	53	43	40	38	47
Crop phase^y
CS	76A	65A	45	52	47	48
C1	75A	58AB	43	47	44	44
C2	54B	40B	45	40	34	51
Nematicide
Without fluopyram	70	54	46	49	38	47
With fluopyram	67	54	43	44	45	48
ANOVA (P-values)
Irrigation (I)	0.30	0.71	0.75	0.16	0.25	0.98
Crop (C)	0.02*	0.01**	0.99	0.34	0.13	0.55
I × C	0.74	0.99	0.64	0.12	0.24	0.72
Nematicide (N)	0.40	0.98	0.61	0.32	0.07	0.72
I × N	0.77	0.88	0.88	0.51	0.92	0.51
C × N	0.43	0.91	0.38	0.63	0.02*	0.58
I × C × N	0.23	0.91	0.68	0.17	0.92	0.19

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

EI, Enrichment Index; LSD, least significant difference.

Table 7

Effects of irrigation, crop phase, and nematicide application on MI in 2017 and 2018.

	Pi^x	Pm	Pf	Pi	Pm	Pf
Irrigation
Irrigated	1.84	2.23	2.33	2.09	2.19	2.25
Rainfed	1.71	2.17	2.24	2.13	2.21	2.08
Crop phase^y
CS	1.71	2.09	2.46	2.02	2.21	2.09
C1	1.73	2.27	2.45	2.17	2.19	2.24
C2	1.88	2.23	1.97	2.13	2.20	2.16
Nematicide
Without fluopyram	1.77	2.25	2.31	2.12	2.26a	2.27a
With fluopyram	1.78	2.15	2.25	2.09	2.14b	2.06b
ANOVA (P-values)
Irrigation (I)	0.17	0.07	0.06	0.75	0.44	0.16
Crop (C) I × C	0.23 0.84	0.07 0.91	0.16 0.90	0.25 0.73	0.95 0.59	0.58 0.81
Nematicide (N)	0.84	0.31	0.93	0.41	0.02*	<0.01**
I × N	0.67	0.83	0.08	0.27	0.77	0.35
C × N	0.45	0.28	0.61	0.08	0.30	0.01**
I × C × N	0.14	0.80	0.64	0.17	0.61	0.22

[i] Different letters in columns denote means separation for significant (P ≤ 0.05) main effects of irrigation, crop phase, or nematicide using Fisher’s LSD test (P ≤ 0.05).

^yC1 and C2 are first- and second-year conventional cotton, respectively, with previous 1 yr peanut; CS is sod-based cotton with previous 1 yr peanut with previous 2 yr bahiagrass.

* and ** represent significant effects at P ≤ 0.05 and P ≤ 0.01, respectively.

LSD, least significant difference.

Fungivore (left) and bacterivore (right) population density (nematodes/100 cm³ soil) in midseason 2017 soil samples. CS is the cotton phase of the sod-based rotation, C1 is first-year conventional cotton, and C2 is second-year conventional cotton. Without Nematicide and With Nematicide refer to absence or presence of fluopyram, respectively. Different letters denote significant differences between nematicide treatments within crop phase (Fisher’s LSD, P ≤ 0.05). LSD, least significant difference.

Bacterivore population density (nematodes/100 cm³ soil) in harvest 2018 (right) soil samples. CS is the cotton phase of the sod-based rotation, C1 is first-year conventional cotton, and C2 is second-year conventional cotton. Without Nematicide and With Nematicide refer to absence or presence of fluopyram, respectively. Different letters denote significant differences between nematicide treatments within crop phase (Fisher’s LSD, P ≤ 0.05). LSD, least significant difference.

Omnivore population density (nematodes/100 cm³ soil) in harvest 2018 soil samples. CS is the cotton phase of the sod-based rotation, C1 is first-year conventional cotton, and C2 is second-year conventional cotton. Without Nematicide and With Nematicide refer to absence or presence of fluopyram, respectively. * indicates significant nematicide effect within the given crop (Fisher’s LSD, P ≤ 0.05). LSD, least significant difference.

Basal Index (left) and EI (right) based on midseason 2018 soil samples. CS is the cotton phase of the sod-based rotation, C1 is first-year conventional cotton, and C2 is second-year conventional cotton. Without Nematicide and With Nematicide refer to absence or presence of fluopyram, respectively. Different letters denote significant differences between nematicide treatments within crop phase (Fisher’s LSD, P ≤ 0.05). EI, Enrichment Index; LSD, least significant difference.

Maturity Index (left) and SI (right) based on harvest 2018 soil samples. CS is the cotton phase of the sod-based rotation, C1 is first-year conventional cotton, and C2 is second-year conventional cotton. Without Nematicide and With Nematicide refer to absence or presence of fluopyram, respectively. Different letters denote significant differences between nematicide treatments within crop phase (Fisher’s LSD, P ≤ 0.05). LSD, least significant difference; SI, Structure Index.

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DOI: https://doi.org/10.2478/jofnem-2022-0046 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X

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Language: English

Submitted on: Jun 30, 2022

Published on: Oct 29, 2022

Published by: Society of Nematologists, Inc.

In partnership with: Paradigm Publishing Services

Publication frequency: 1 issue per year

Keywords:

bahiagrass,

cotton,

crop rotation,

ecology,

fluopyram,

free-living nematodes,

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© 2022 Lesley A. Schumacher, Zane J. Grabau, David L. Wright, Ian M. Small, Hui-Ling Liao, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 54 (2022): Issue 1 (February 2022)

Effects of Grass-Based Crop Rotation, Nematicide, and Irrigation on the Nematode Community in Cotton

Figures & Tables

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