Organic or conventional production system and nutrient rate affect the nematode community in carrot production

	Year 1 (2016–2017)
Date	20 Oct	28 Nov	13 Dec	20 Dec	27 Dec	3 Jan	10 Jan	17 Jan	24 Jan	31 Jan	7 Feb	14 Feb	20 Feb	28 Feb	7 Mar	14 Mar	21 Mar
DAP^a:	‒9	30	45	52	59	66	73	80	87	94	101	108	114	122	129	136	143
Treatment (total kg N/ha)	-----------------------------------------N applied each date (kg/ha)--------------------------------------------
168	28.0	17.5		17.5			17.5		17.5		17.5		17.5		17.5		17.5
224	28.0	24.5		24.5			24.5		24.5		24.5		24.5		24.5		24.5
280	28.0	31.5		31.5			31.5		31.5		31.5		31.5		31.5		31.5
336	28.0	20.5	20.5		20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5
392	28.0	24.3	24.3		24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3
	Year 2 (2017–2018)
Date:	27 Oct	4 Dec	18 Dec	21 Dec	28 Dec	4 Jan	11 Jan	16 Jan	25 Jan	1 Feb	8 Feb	13 Feb	22 Feb	1 Mar	8 Mar	13 Mar	22 Mar
DAP:	‒6	32	46	49	56	63	70	75	84	91	98	103	112	119	126	131	140
Treatment (total kg N/ha)	-----------------------------------------N applied each date (kg/ha)--------------------------------------------
168	28.0	17.5		17.5			17.5		17.5		17.5		17.5		17.5		17.5
224	28.0	24.5		24.5			24.5		24.5		24.5		24.5		24.5		24.5
280	28.0	31.5		31.5			31.5		31.5		31.5		31.5		31.5		31.5
336	28.0	20.5	20.5		20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5	20.5
392	28.0	24.3	24.3		24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3	24.3

1 Note: ^aDAP is days after planting.

Table 2.

Nutrient amendment application timing by rate treatment in organic production for both Year 1 and Year 2.

Treatment (total kg N/ha)	At planting^a	5 WAP^b	7 WAP
N rate (kg/ha) per timing
168	84	42	42
224	112	56	56
280	140	70	70
336	168	84	84
392	196	98	98

1 Notes: ^aIn Year 1 (2016), preplant fertilizer was applied on 20 Oct, carrots were planting on 24 Oct and replanted on 14 Nov due to poor stand in initial planting; ^bWAP is weeks after planting. For each treatment 50% of total was applied at planting with 25% each applied at 5 and 7 WAP.

Table 3.

Schedule for data collection and trial establishment.

	Year 1 (2016–2017)		Year 2 (2017–2018)
Item	Conventional	Organic	Conventional	Organic
Soil fumigation	9 Sep (‒50)	N/A^a	13 Oct (‒21)	N/A
Date planted	29 Oct (0)	14 Nov (0)^b	2 Nov (0)	15 Nov (0)
Date harvested	10–11 Apr (170)	17 Apr (161)	19–20 Apr (168)	20 Apr (155)
Midseason soil sampling	16 Dec (48)	6 Jan (53)	2 Jan (61)	2 Jan (48)
Harvest soil sampling	28 Mar (157)	28 Mar (141)	13 Mar (131)	13 Mar (118)

1 Notes: Numbers in parentheses are days before transplanting (DBP) or days after transplanting (DAP). ^aIn organic production, Purpureocillium liacinum was applied for nematode biocontrol; ^bIn Year 1 organic production, carrots were initially planted on 24 Oct, but replanted due to poor stand.

Table 4.

Nematode genera in organic and conventional trials.

			-----------Organic----------		-------Conventional---------
Nematode genera	Feeding group	cp value	Relative abundance^a	Mean abundance^b	Relative abundance	Mean abundance
Rhabditis	Bacterivore	1	25.95%	506	14.38%	79
Panagrolaimus	Bacterivore	1	1.67%	33	0.03%	0
Diplogaster	Bacterivore	1	0.04%	1	0.14%	1
Cephalobus	Bacterivore	2	11.27%	220	56.71%	310
Acrobeles	Bacterivore	2	9.31%	182	1.07%	6
Eucephalobus	Bacterivore	2	9.08%	177	7.49%	41
Cervidellus	Bacterivore	2	0.74%	14	0.08%	0
Heterocephalobus	Bacterivore	2	0.15%	3	N/A	N/A
Plectus	Bacterivore	2	0.12%	2	0.31%	2
Filenchus	Fungivore	2	5.91%	115	0.77%	4
Aphelenchus	Fungivore	2	3.92%	77	6.21%	34
Aphelenchoides	Fungivore	2	3.26%	64	5.00%	27
Ditylenchus	Fungivore	2	0.36%	7	0.07%	0
Diphtherophora	Fungivore	3	0.23%	4	0.10%	1
Paratylenchus	Herbivore	2	3.21%	63	0.08%	0
Malenchus	Herbivore	2	0.89%	17	0.02%	0
Mesocriconema	Herbivore	3	11.45%	223	4.62%	25
Pratylenchus	Herbivore	3	6.52%	127	0.24%	1
Meloidogyne	Herbivore	3	0.18%	4	0.82%	4
Paratrichodorus	Herbivore	4	0.23%	5	0.28%	2
Axonchium	Herbivore	5	0.10%	2	0.16%	1
Thonus	Omnivore	4	1.48%	29	0.36%	2
Mesodorylaimus	Omnivore	4	0.36%	7	N/A	N/A
Eudorylaimus	Omnivore	4	0.14%	3	0.04%	0
Aporcelaimellus	Omnivore	5	2.94%	57	0.33%	2
Paraxonchium	Omnivore	5	0.04%	1	N/A	N/A
Seinura	Predator	2	N/A	N/A	0.50%	3
Discolaimus	Predator	5	0.13%	3	0.02%	0

1 Notes: Data combined across sampling dates and years. ^aRelative abundance is proportion of total nematode abundance across all sampling dates and years within production system. Only nematode genera with 0.1% relative abundance in either organic or conventional production are shown; ^bMean abundance is mean nematodes/100 cm³ soil across all sampling dates and years within production system.

Nematode soil abundances for different trophic groups as affected by production system. Data are combined across two years. Data points and error bars represent means and standard errors, respectively. ‘Conventional’ and ‘organic’ are conventional and organic production systems, respectively. An ‘*’ beside organic production mean indicates significant production system effects for a given season (ANOVA, p < 0.05).

Nematode soil abundances for common genera as affected by production system. Data are combined across two years. Data points and error bars represent means and standard errors, respectively. ‘Conventional’ and ‘organic’ are conventional and organic production systems, respectively. An ‘*’ beside organic production mean indicates significant production system effects for a given season (ANOVA, p < 0.05).

Nematode community indices as affected by production system. Data are combined across two years. Data points and error bars represent means and standard errors, respectively. ‘Conventional’ and ‘organic’ are conventional and organic production systems, respectively. An ‘*’ beside organic production mean indicates significant production system effects for a given season (ANOVA, p < 0.05). Diversity is Hill’s N1 diversity based on nematode genera or trophic guilds.

Table 5.

Organic production: nematode soil abundances for bacterivores and fungivores (total and individual genera) as affected by nitrogen rate^a.

Year 1			Year 2		Year 1		Year 2
Rate (kg N/ha)	Pm^b	Pf	Pm	Pf	Pm	Pf	Pm	Pf
Bacterivores					Fungivores
168	192 b	719 b	1,615	1,246	89	144 bc	452	327
224	223 b	768 b	1,939	1,150	79	101 c	389	191
280	259 ab	703 b	1,980	1,274	83	108 c	355	248
336	360 a	1877 a	2,396	1,186	116	229 ab	565	226
392	305 ab	1,124 ab	2,109	1,431	106	276 a	393	335
Rhabditis spp.					Aphelenchus spp.
168	97 b	362 b	757	413	7	23 b	67	21
224	100 ab	361 b	899	466	6	24 b	55	0
280	113 b	251 b	1,017	450	8	17 b	45	31
336	193 a	872 a	1,182	428	11	36 ab	48	10
392	165 ab	487 ab	984	526	13	49 a	96	30
Cephalobus spp.					Aphelenchoides spp.
168	25	38	468	295	33 b	99 bc	102	187
224	41	95	439	189	44 ab	61 c	108	90
280	54	31	534	331	36 b	87 bc	121	139
336	58	87	555	269	61 a	184 ab	207	89
392	33	97	570	190	51 ab	214 a	118	178

1 Notes: ^aValues are mean nematode soil abundances (nematodes/100 cm³ soil); ^bPm and Pf indicate midseason and final nematode soil abundances, respectively. Values for the same variable with different letters in the same column are significantly different according to Fisher’s protected LSD (p < 0.05). Absence of letters indicates there were no significant nutrient rate effects in that season for a particular variable (ANOVA, p > 0.05).

Table 6.

Conventional production: nematode soil abundances for bacterivores and fungivores (total and individual genera) as affected by nitrogen rate^a.

Year 1			Year 2		Year 1		Year 2
Rate (kg N/ha)	Pm^b	Pf	Pm	Pf	Pm	Pf	Pm	Pf
Bacterivores					Fungivores
168	95	220 ab	351	756 b	10	15 b	94	106 b
224	119	156 b	706	1,563 a	19	15 b	203	194 a
280	89	216 ab	542	967 b	7	29 a	148	93 b
336	93	273 a	356	770 b	10	10 b	140	111 b
392	84	316 a	280	829 b	7	13 b	61	51 b
Rhabditis spp.					Aphelenchus spp.
168	2	2	131	73	9	7	70	42
224	2	2	359	214	14	8	138	56
280	4	2	240	149	6	14	99	46
336	1	3	103	116	8	7	53	23
392	2	3	60	108	5	6	45	26
Cephalobus spp.					Aphelenchoides spp.
168	89	214 ab	186	623	1	4	20	62 b
224	115	152 b	295	933	4	5	52	134 a
280	82	211 ab	277	695	1	10	43	46 b
336	89	267 a	210	587	0	1	53	69 ab
392	80	311 a	196	597	1	5	15	23 b

Table 7.

Herbivore and herbivore genera soil abundances as affected by nitrogen rate in organic and conventional production^a.

Organic production					Conventional production
Year 1			Year 2		Year 1		Year 2
Rate (kg N/ha)	Pm^b	Pf	Pm	Pf	Pm	Pf	Pm	Pf
Herbivores
168	80	648	860	260	13	13	80	648
224	87	567	804	359	7	4	87	567
280	85	310	821	312	7	5	85	310
336	92	511	950	367	4	3	92	511
392	75	500	872	350	5	3	75	500
Mesocriconema
168	48	258	342	187	10	10	48	258
224	49	243	332	291	3	2	49	243
280	65	194	436	194	4	3	65	194
336	58	212	446	221	4	1	58	212
392	50	211	444	187	4	2	50	211
Meloidogyne incognita
168	1	0	29 b	18	0	0	1	0
224	2	3	41 b	28	0	0	2	3
280	0	6	98 a	18	0	0	0	6
336	0	0	49 b	43	0	0	0	0
392	0	8	49 b	25	0	0	0	8

Table 8.

Nematode community indices as affected by nitrogen rate in organic and conventional production^a.

Organic production					Conventional production
Year 1			Year 2		Year 1		Year 2
Rate (kg N/ha)	Vm^b	Vf	Vm	Vf	Vm	Vf	Vm	Vf
Structure index
168	37	50	27	25	8	5	10	1.5
224	26	50	36	37	7	5	6	6.6
280	34	48	37	28	7	6	7	9.4
336	28	46	29	24	11	3	16	4.4
392	20	37	18	33	8	3	6	0.3
Enrichment index
168	72 ab	76	73	73	13	10	65	35
224	70 b	71	72	73	18	11	61	42
280	70 ab	69	77	72	19	13	66	41
336	76 a	81	74	76	10	6	59	43
392	75 a	76	74	76	12	8	54	37
Hill’s N1 diversity-genera
168	9.4	9.5	8.6	4.6	2.5	2.1	6.2	3.1
224	9.4	9.8	9.1	4.4	3.0	1.9	5.4	4.0
280	8.8	9.7	8.5	4.5	2.4	2.1	5.2	4.0
336	8.0	8.8	8.9	4.6	2.3	1.4	7.1	4.0
392	8.1	9.8	8.4	4.5	2.3	1.6	4.9	2.8
Hill’s N1 diversity-guild
168	2.0	1.8	4.1	2.8	5.1	5.1	5.3	4.5
224	2.2	1.6	3.4	3.0	4.8	5.2	5.3	4.6
280	2.1	1.8	3.6	2.9	4.8	4.8	5.2	4.4
336	1.9	1.3	4.2	2.9	4.5	4.6	5.0	4.5
392	1.9	1.5	3.4	2.6	4.4	5.1	4.8	4.8

1 Notes: ^aValues are mean nematode soil abundances (nematodes/100 cm³ soil); ^bVm and Vf indicate midseason and final values, respectively. Values for the same variable with different letters in the same column are significantly different according to Fisher’s protected LSD (p < 0.05). Absence of letters indicates there were no significant nutrient rate effects in that season for a particular variable (ANOVA, p > 0.05).

References

Authors

Metrics

Articles in this issue

DOI: https://doi.org/10.21307/jofnem-2021-082 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X

Journal RSS Feed

Language: English

Page range: 1 - 18

Published on: Oct 13, 2021

Published by: Society of Nematologists, Inc.

In partnership with: Paradigm Publishing Services

Publication frequency: 1 issue per year

Keywords:

Carrot,

Organic,

Related subjects:

© 2021 Zane J. Grabau, Danielle D. Treadwell, Jose J. Perez Orozco, David N. Campbell, Robert C. Hochmuth, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 53 (2021): Issue 1 (January 2021)

Organic or conventional production system and nutrient rate affect the nematode community in carrot production

Figures & Tables

Table 1.

Table 2.

Table 3.

Table 4.

Figure 1:

Figure 2:

Figure 3:

Table 5.

Table 6.

Table 7.

Table 8.

Paradigm

My account