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Figure 1
Soil sampling sites at Central, Manyatta, and Nembure regions in Embu County, Kenya.
Figure 2
Abundance (mean ± standard error) of nematode genera in 250 g of soil from sweet potato fields in Central, Manyatta, and Nembure regions of Embu County, Kenya at 0 cm to 30 cm and 30 cm to 60 cm depths. Cos: Coslenchus; Hel: Helicotylenchus; Hem: Hemicycliophora; Hop: Hoplolaimus; Lon: Longidorus; Mal: Malenchus; Mel: Meloidogyne; Pra: Pratylenchus; Psi: Psilenchus; Rol: Rotylenchulus; Rot: Rotylenchus; Scut: Scutellonema; Tric: Trichodorus; Tyrh: Tylenchorhynchus; Tyl: Tylenchus; Xip: Xiphinema.
Figure 3
Abundance (mean ± standard error) of nematode genera in 250 g of soil from sweet potato fields in Central, Nembure, and Manyatta regions of Embu County, Kenya. Cos: Coslenchus; Hel: Helicotylenchus; Hem: Hemicycliophora; Hop: Hoplolaimus; Lon: Longidorus; Mal: Malenchus; Mel: Meloidogyne; Pra: Pratylenchus; Psi: Psilenchus; Rol: Rotylenchulus; Rot: Rotylenchus; Scut: Scutellonema; Tric: Trichodorus; Tyrh: Tylenchorhynchus; Tyl: Tylenchus; Xip: Xiphinema.
Figure 4
Additive γ diversity partitioning (into α and β components) of (A) nematode genus richness, (B) Shannon–Weaver diversity, and (C) Simpson diversity in sweet potato fields in Central, Manyatta, and Nembure regions in Embu County, Kenya at 0 cm to 30 cm and 30 cm to 60 cm depths.
Figure 5
NMDS ordination of nematode communities in sweet potato fields in Central, Manyatta, and Nembure regions in Embu County, Kenya at 0 cm to 30 cm and 30 cm to 60 cm depths (NMDS Stress = 0.2). NMDS, nonmetric multidimensional scaling.
Figure 6
Coinertia analysis of nematode genera and soil properties at 0 cm to 30 cm depth in Central, Manyatta, and Nembure regions in Embu County, Kenya (RV = 0.13, P = 0.05, Monte Carlo permutation test).
Soil properties in sweet potato fields at 0–30 cm depth in Central, Manyatta, and Nembure regions in Embu County, Kenya.
Soil property
Central
Manyatta
Nembure
P value
Mean
SE
Mean
SE
Mean
SE
pH
4.89
0.23
4.70
0.16
4.72
0.14
0.74
Total Nitrogen%
0.36
0.01
0.38
0.02
0.29
0.03
0.02*
Total Organic Carbon%
4.04
0.14
4.25
0.20
3.36
0.31
0.02*
Phosphorus ppm
25.31
4.43
17.33
2.09
14.86
2.76
0.08
Potassium meq%
0.92
0.16
1.10
0.12
0.84
0.14
0.42
Calcium meq%
2.56
0.69
2.55
0.65
1.81
0.62
0.67
Magnesium meq%
3.39
0.34
3.29
0.33
3.29
0.28
0.97
Manganese meq%
0.79
0.04
0.85
0.05
0.66
0.05
0.02*
Copper ppm
4.83
2.09
3.55
1.34
1.26
0.30
0.26
Iron ppm
27.25
4.15
33.38
7.11
26.68
5.00
0.64
Zinc ppm
34.12
3.49
23.01
2.54
16.18
2.47
<0.0001***
Sodium meq%
0.58
0.03
0.44
0.03
0.46
0.04
0.02*
Sand (%)
10.00
3.89
15.87
5.50
13.71
6.24
0.72
Clay (%)
77.63
3.73
72.13
5.28
75.29
6.15
0.74
Silt (%)
12.38
0.33
12.00
0.34
11.00
0.35
0.02*
Two-way analysis of variance (P values) of region, depth, and their interaction on nematode genera, Pielou’s evenness, Shannon–Weaver, and Simpson diversity indices in sweet potato fields in Central, Manyatta, and Nembure regions of Embu County, Kenya.
Region
Depth
Region × depth
Nematode genera
Coslenchus
0.11
0.64
0.72
Helicotylenchus
0.97
0.97
0.93
Longidorus
0.98
0.08
0.14
Meloidogyne
0.4
0.35
0.71
Pratylenchus
0.1
0.91
0.81
Rotylenchulus
0.83
0.68
0.83
Rotylenchus
0.65
0.36
0.96
Scutellonema
0.08
0.81
0.75
Trichodorus
0.49
0.17
0.3
Tylenchorhynchus
0.06
0.33
0.83
Tylenchus
0.15
0.32
0.01*
Xiphinema
0.78
0.9
0.07
Psilenchus
<0.0001***
0.93
1
Hemicycliophora
0.01*
0.9
0.98
Hoplolaimus
0.05*
0.56
0.71
Malenchus
0.15
0.79
0.93
Diversity indices
Shannon–Weaver diversity
0.04*
0.03*
0.53
Simpson diversity
0.08
0.05*
0.84
Pielou’s evenness
0.89
0.41
0.24
Simpson and Shannon–Weaver diversity indices of nematode communities in sweet potato fields in Central, Manyatta, and Nembure regions in Embu County, Kenya at 0 cm to 30 cm and 30 cm to 60 cm depths.