I also dedicate this study to my husband Pietro and our beautiful daughters Jana and Liana. To my husband, I thank you for all your support (providing the trial site, preparing the site, planting and harvesting and much more) and for helping me get to the end.
INTRODUCTION AND LITERATURE REVIEW
INTRODUCTION
Help contribute to sustainable potato production in South Africa by investigating the effect of an organic nematicide product compared to existing registered chemical products on nematode assemblages in a potato field (located in the Tzaneen area, Limpopo Province, South Africa) in combination with grass cover. The specific objectives of this study were to investigate whether: .. i) an environmentally friendly nematicide product, Kalahari 3:1 (with neem modified cow manure pellet), is effective in reducing the population density of predominant PPN species, both by application and alone and in various combinations with two registered nematicide chemical products; .. ii) the quality and yield of the potato crop will be improved by the application of the alternative product and . iii) this product, as well as grass cover cultivation, positively impact beneficial nematode assemblages that have been used as soil health bioindicators.
POTATO (SOLANUM TUBEROSUM L.)
- Origin…
- Classification
- Anatomy of the potato
- Economical and social importance of the potato
- Potato production in South Africa
Diseases caused by fungi, bacteria and viruses threaten the potential productivity and sustainability of local potato production (Van der Waals et al., 2013 & 2016). Plant parasitic nematodes are another pest that damages local potato crops (Jones et al., 2017) and are discussed below.
NEMATODES
- Nematode sampling, extraction, counting and identification
- Morphological identification of plant-parasitic nematodes
- Molecular techniques used to identify plant-parasitic nematodes
- Morphological and molecular identification of beneficial soil nematodes
- Basic nematode morphology and physiology
- Basic life cycle of nematodes
- Reproduction
- Survival Strategies
- Plant-parasitic nematodes’ damage potential to potato
- Root-knot nematodes
- Lesion nematodes
- Beneficial nematodes and their use as bio-indicators of soil health
- Soil health and soil quality indices
- Bio-indicators and beneficial soil nematodes
Roundworms (Geocenamus Throne & Malek, 1968, Telotylenchus and Tylenchorhynchus (Cobb, 1913)) occur mostly in the Sandveld, Gauteng, Loskop Valley and Mpumalanga areas (Marais et al., 2015). At least 15 species of LN have been reported to infect potatoes worldwide (Lima et al., 2018).
MANAGEMENT STRATEGIES
- Chemical control
- Alternative strategies for management of plant-parasitic nematodes
- Biological control
- Soil amendments, cover and green manure crops /organic amendments
- Other strategies
Clean polyethylene sheets are placed over wet soil (summer) to increase soil surface temperature (>50 °C) (Dutta et al., 2019). It can be expensive and labor intensive to install, especially on a large scale (Dufour et al., 2003).
Evaluation of synergistic effect of neem and poultry manure on root knot nematode (Meloidogyne spp.). Biological control of root nematode Meloidogyne javanica (Chitwood) using Bacillus isolates on soybean. Effect of neem-based products on root nematode, Meloidogyne incognita and growth of tomato.
Effect of liquid organic-mineral fertilizer formulation on control of root nematodes in potatoes.
MORPHOLOGICAL AND MOLECULAR IDENTIFICATION OF
- INTRODUCTION
- MATERIALS AND METHODS
- Collection and rearing of Meloidogyne spp
- Isolation of mature Meloidogyne spp. females
- Morphological identification of Meloidogyne spp. females
- Molecular identification of mature Meloidogyne spp. females
- RESULTS
- Morphological identification of Meloidogyne spp. females
- Molecular identification of Meloidogyne spp. females
- DISCUSSION
- CONCLUSION
- REFERENCES
The perineal pattern consists of the anus and vulva (perineum), lateral lines, cuticular striae, tail end and phasmids (Hirschmann, 1985; Karssen & Van Aelst, 2001). The scale was used to indicate the size of the DNA bands (amplification fragment size) of each RKN species found at the test site. Effects of Mi-1 and the N-knot nematode resistance gene on infection and reproduction of Meloidogyne enterolobii in tomato and pepper cultivars.
Genetic diversity of the root-knot nematode Meloidogyne enterolobii and development of a SCAR marker for this guava pest species.
EFFECTS OF A NEEM-AMENDED PRODUCT ON PLANT-PARASITIC
INTRODUCTION
In addition to the use of chemicals, alternative nematode control strategies such as crop rotation, organic soil amendments or resistant or tolerant cultivars are also implemented in many potato cropping systems (Jones et al., 2017). Several studies have shown that, when used as green manure, seed oil cake and neem oil extract, these components have nematicidal (killing nematodes) and/or nematostatic (inhibiting nematode movement or reproduction) effects (Campos et al., 2016; Jones, 2017). ). A more recent study conducted by Rossi et al. 2021) that focused on the use of an organic liquid fertilizer containing neem extract showed no significant differences between any of the treatments used.
Cow manure used as a solo treatment to reduce RKN and other PPN has shown variable results (Kimpinski et al., 2003).
MATERIALS AND METHODS
- Study area
- Trial layout and soil sampling
- Nematode sampling: root and soil
- Long-term precipitation and temperature data
- Nematode analyses
- Soil…
- Roots
- Counting of nematodes
- Plant-parasitic and beneficial soil nematodes
- Damage index of potato tubers
- Statistical Analysis
The soil of the five subsamples was placed in the same plastic bag, thoroughly mixed and clearly marked. In the nematode laboratory, a representative sample of each plot was used for nematode analysis, while the rest of the soil was used to perform chemical and physical soil analyzes for each plot. The supernatant was decanted through stacked sieves of 45 μm aperture and 25 μm aperture and the sediment was washed into the bucket.
The nematodes contained in the supernatant were decanted through a 25 µm aperture sieve and washed with distilled water to remove the sucrose solution.
RESULTS
- Plant-parasitic nematode data from 250 ml soil
- Root-knot nematodes
- Lesion nematodes
- Spiral nematodes
- Ring nematodes
- Plant-parasitic nematode data from 30 g roots
- Root-knot nematodes
- Lesion nematodes
- Spiral nematodes
- Plant-parasitic nematode eggs
- Root-knot nematode damage index on potato tubers
No significant differences were evident between the treatments per sampling interval, nor was there a significant interaction for treatments x sampling times (Table 3.8) indicating that nematode population densities were quite similar for all treatments and sampling times. No significant differences were evident between the treatments per sampling interval, nor was there a significant interaction for treatments x sampling times (Table 3.10) indicating that RKN population densities in 30 g roots were quite similar for all treatments and sampling times, although it did increase over the sampling times. Significance level for Repeated measures ANOVA in capital letters; different letters indicate significant differences across rows for sampling intervals;.
Significance level for repeated measures ANOVA in capital letters; different letters indicate significant differences between rows for sampling intervals; different lowercase letters per column indicate significant differences between treatments for individual sampling interval).
DISCUSSION
The nematicidal effect of manure treatment showed different results among the different cultivars used (Osei et al., 2017). Although the population density has shown a slight decline over time, this cannot be attributed directly to the use of neem-supplemented cow dung granules. Therefore, it might be interesting to investigate a different formulation with a higher concentration of neem extract.
This may also have played a role in the plants' ability to absorb the fertilizer component of the Kalahari 3:1 treatments.
CONCLUSION
Effect of organic amendments on nematode galling index and egg mass production in potato inoculated with root-knot nematode. Effect of leaf extracts of some medicinal plants on root-knot nematode Meloidogyne incognita and eggplant Solanum melongena. Effect of poultry manure on the growth, yield and root-knot nematode (Meloidogyne spp.) infestation of carrot (Daucus carota L.).
Distribution and genetic diversity of root-knot nematodes (Meloidogyne spp.) in potatoes from South Africa.
EFFECTS OF A NEEM-AMENDED PRODUCT AND A SUCCESSIVE
INTRODUCTION
Studying the effect of these activities on beneficial soil nematodes can help with the development and implementation of more sustainable agricultural practices (Kapp, 2013; . Moura & Franzener, 2017; Sofo et al., 2021). Agricultural practices, such as cultivation and monocrop systems have a significant effect on various microbial processes in the soil (Sofo et al., 2021). A short fallow period was not sufficient for the beneficial soil nematodes to recover (Torres et al., 2006).
This means that cover cropping systems will improve the diversity and abundance of beneficial soil nematode populations in the soil compared to a bare fallow period (Kim et al., 2020).
MATERIALS AND METHODS
- Site and design
- Nematode sampling and analyses: root and soil
- Statistical Analysis
102. nematicides on beneficial soil nematodes and iii) what is the effect of a consecutive 27-month tillage of grass on the community composition of beneficial soil nematodes compared to pre-sowing. The Nematode Indicator Joint Analysis Tool (NINJA), developed by Sieriebrienikov et al. 2014) to aid in the study of soil ecosystems was also used to determine what role nematode bioindicators played in the specific trial area in terms of soil health. Data sets, including beneficial nematode genera/families determined at pre-planting and 27 months later, were imported into NINJA.
The tool uses various indices assigned to nematode families/genera to determine soil health.
RESULTS
- Beneficial nematode data from 250 ml soil
- Total beneficial nematode counts from soil
- Bacterivore nematode counts from soil
- Fungivore nematode counts from soil
- Omnivore nematode counts from soil
- Principal component analysis
- Soil faunal analysis (NINJA)
The abundance of bacteria for treatments 1 and 3 at pre-planting was significantly lower than that of sampling intervals 2 and 3. Maturity index (MI) of plot at pre-planting and after fallow period sampling intervals. The treatments are marked numerically, while the sampling intervals are indicated by letters (a . = pre-planting interval; b = post-fallow interval).
The treatments are marked numerically, while the sampling intervals are indicated by letters (a . = before planting; b = after fallow period).
DISCUSSION
This supports the findings in this study, where the abundance of bacteriophages increased while the abundance of PPN decreased slightly after a 27-month fallow period of white buffalo grass. The results of this study showed an increase in the abundance of bacterivorous nematodes only, similar to that observed in the study conducted by Liu et al. 2016), while the abundance of fungal nematodes was not correlated with the increase in organic material. Natural brush regrowth dust showed the lowest percentage of PPN control than other cover crops tested in the experiment of Adediran et al.
In addition to the extreme drought conditions that occurred during the duration of this study, the grass fallow period may have been too short to cause significant changes in the beneficial nematode community.
CONCLUSION
This suggests that the soil was under pressure before planting activities began and little changed over time. This is supported by the minimal changes in the abundance of omnivores in the field over time, indicating that the soil remained disturbed before the start of the trial and did not improve during the fallow period. As indicated by Gomes et al. 2003), omnivores from the Dorylaimidae, the only omnivorous family found in both soil and field root samples, are highly sensitive to soil disturbances caused by agricultural practices.
Further studies can also be conducted to determine which additional agricultural management practices will improve the soil health of a site such as the one used in this study, while also improving the beneficial soil nematode community and promoting more sustainable, environmentally friendly agriculture.
Effects of organic mulches on soil microfauna in the apple root zone: implications for nutrient fluxes and functional diversity of the soil food web. Effect of synthetic fertilizer and agricultural compost on the soil nematode community in long-term crop rotation plots: a morphological and metabarcoding approach. Response of soil nematode communities to fertilization in root-associated and large-scale soils of a rice-wheat agroecosystem.
Indicators for soil quality assessment: a mini-review. http://entnemdept.ufl.edu/creatures/nematode/soil_nematode.htm#:~:text=Free%2Dliving%20ne matodes%20are%20very,fungi%20 Which%20decompose%20organic%20matter.
CONCLUSION AND FUTURE PROSPECTS
TESTING OF THE HYPOTHESES
In terms of beneficial soil nematode data recorded in this study, the hypothesis could not be supported either. Although the results of this study showed that the total number of beneficial soil nematodes varied over time in all treated and untreated plots, they support those of the mentioned authors to some extent. The use of the neem-modified cow manure as a stand-alone product had the most beneficial effect on the overall beneficial soil nematode population diversity and density, compared to the use of registered nematicides, either alone or in the various combinations tested.
In this trial, there were no significant associations between soil properties and the distribution of the beneficial soil nematode community, related to the results found by Nielsen et al., 2014.
POTENTIAL FUTURE RESEARCH
This varied response of beneficial soil nematode populations to the addition of organic compost is supported by other studies (Herren et al., 2020). When comparing the effects of the natural fallow period of White Buffalo grass on soil nematode composition in this field with the soil nematode community of the field before treatments and planting began, the fallow period generally increased the population density of bacterivores while the density of the bacterivores declined. herbivores. After subjecting the field data to NINJA and studying the metabolic footprint analysis, soil nematode populations were mostly concentrated in the third square; thus, the soil is classified as degraded and depleted.
Therefore, to improve the overall soil health and the beneficial composition of the soil nematode community, additional management and improvement practices will be needed.
