Table 1.
Experimental treatments.
| Treatment name (product name) | Manufacturer | Active ingredient(s) | Description | Application instructions |
|---|---|---|---|---|
| Sterilized | NA | NA | Soil sterilized with an autoclave (1 hr, 70˚C) | NA |
| Control | NA | NA | Soil infested with Meloidogyne spp.; untreated | NA |
| Oxamyl a (Vydate®) | Corteva | Oxamyl | Commercial chemical nematicide | 0.04 g/liter soil/pot/plant; top layer |
| Garlic extract b | Anonymous | Allium sativa extract | Biological nematicide | 0.04 g/liter soil/pot/plant; top layer |
| Chitosan HCl (DB Chitis 3.0) | De Broers | Chitin hydrochloride | Basic substance | 50 ml/liter; 4 ml/plant |
| Microorganisms (Biovin) | Plant Health Cure | Microorganisms and micronutrients | Biostimulant/fertilizer | 40 g/10-liter soil; 1-liter soil/pot/plant |
| Plant oils | Anonymous | Plant oils | Biostimulant | 4 ml/liter; 4 ml/plant |
| Sea minerals c | Anonymous | Unprocessed sea minerals | Biostimulant/fertilizer | 0.5 g/liter; 4 ml/plant; every 3 weeks |
| Plant extracts (Nemater) | Pireco | Plant extracts | Biostimulant | 5 ml/liter; 5 ml/plant |
| Soldier fly waste (Flytilizer X) | Protix | Insect skins, frass, food fibers | Biostimulant | 2 g/liter soil/pot/plant |
1 Note: aChemical formula: C7H13N3O3 bLiberated Allicin transformed polysulfides cContains: magnesium, calcium, sulphur, potassium, phosphorus, nitrogen, iron, boron, sodium, chloride and salt crystals. All of the reagents listed below were applied individually to the soil in which each plant grew and the chemical and biological nematicides, and the so-called basic substance, were applied in combination with the five biostimulant treatments (i.e., 3 × 5 = 15 combined treatments + 10 individual treatments = 25 total treatments).
Table 2.
Results of statistical analyses.
| Response variable | Sum of squares | Mean sum of squares | Df | F-value (p-value) |
|---|---|---|---|---|
| Aboveground fresh weight | 11.6 | 0.5 | 24, 961 | 11.1 (<0.001) |
| Aboveground dry weight | 12.7 | 0.5 | 24, 962 | 10.2 (<0.001) |
| Belowground fresh weight | 18.9 | 1.0 | 24, 937 | 13.3 (<0.001) |
| Belowground dry weight | 25.6 | 1.1 | 24, 828 | 15.2 (<0.001) |
| Root-knot index | 59.3 | 2.5 | 24, 952 | 10.9 (<0.001) |
| Total nematodes | 31.2 | 1.3 | 24, 93 | 1.9 (0.019) |
| Meloidogyne spp. (soil) | 18.4 | 0.8 | 24, 100 | 2.2 (0.004) |
| Meloidogyne spp. (roots) | 57.0 | 2.4 | 24, 97 | 2.8 (<0.001) |
| Total plant-feeding nematodes | 37.9 | 1.6 | 24, 100 | 2.7 (<0.001) |
| Bacterial-feeding nematodes | 33.2 | 1.4 | 24, 92 | 2.1 (0.008) |
| Fungal-feeding nematodes | 13.1 | 0.6 | 24, 93 | 2.4 (0.001) |
| Carnivore-omnivore nematodes | 1.3 | 0.1 | 24, 100 | 2.1 (0.007) |
| Maturity index | 0.5 | 0.0 | 24, 95 | 2.1 (0.005) |
| Enrichment index | 1.0 | 0.0 | 24, 97 | 2.9 (<0.001) |
| Structure index | 53.4 | 2.3 | 24, 94 | 3.5 (<0.001) |
1 Note: Data ln x or ln (x + 1) transformed before analysis. Aboveground fresh and dry weight n = 1,000; belowground fresh weight: n = 975; belowground dry weight: n = 866; Root-knot index: n = 990. Df = degrees of freedom, denominator degrees of freedom. All nematode variables: n = 120. The effects of the treatments on above- and belowground fresh and dry weight, the root-knot index (i.e., the level of damage caused to the chrysanthemums by the root-knot nematodes), the different nematode feeding groups, the number of Meloidogyne spp. extracted from the soil and the roots of the chrysanthemums and the nematode Enrichment, Maturity and Structure indices.
Figure 1:
Aboveground fresh (A) and dry (B) and belowground fresh (C) and dry (D) weight of the chrysanthemums exposed to the different treatments at the end of the experiment. Within each panel, bars with different letters differ statistically significantly from one another (Tukey’s HSD p ≤ 0.05). Data shown are means ± SE.
Figure 2:
The root-knot index show the amount of damage caused by root-knot nematodes (Meloidogyne spp.) in the chrysanthemum roots: 0=no root-knots, 10=root entirely covered in knots and plant is dead or dying (A). Total nematodes (B) and Meloidogyne spp. in the ground (C) and Meloidogyne spp. extracted from the roots (D) of the chrysanthemums at the end of the experiment. Within each panel, bars with different letters differ statistically significantly from one another (Tukey’s HSD p ≤ 0.05); no letters indicate no statistically significant differences were detected. Data shown are means ± SE.
Figure 3:
Total plant-feeding (A), bacterial-feeding (B), fungal-feeding (C) and carnivore-omnivore (D) nematodes that were extracted from soils of the chrysanthemums at the end of the experiment. Within each panel, bars with different letters differ statistically significantly from one another (Tukey’s HSD p ≤ 0.05). Data shown are means ± SE.
Figure 4:
Effect of the treatments on the nematode Maturity Index (A) and the Colonizer-persister Triangle (B). Data shown are means ± SE.
Figure 5:
Effect of the treatments on the nematode Enrichment Index (A), Structure Index (B) and the food web analysis (including interpretation scheme inset) (C). Within A) and B), bars with different letters differ statistically significantly from one another (Tukey’s HSD p ≤ 0.05). Data shown are means ± SE.