Impact of low-cost management techniques on population dynamics of plant-parasitic nematodes in sweet potato (original) (raw)
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Acta Oecologica, 2020
Maize and beans contribute significantly to food security in Kenya. Farming practices used in production of these crops may affect nematode community assemblages and influence agricultural productivity. Information on response of nematofauna, particularly free-living nematodes, under various agronomic practices in Kenyan maize-beans intercrop is scarce. This study reports on the effects of farming practices on nematode community dynamics, ecological and functional indices, nematode metabolic footprints, and predator-prey relationship in maize-beans cropping systems in Mwea, Kenya. The field trials were set up in two seasons in a randomized complete block design with each treatment consisting of four replicates. The treatments included cow manure plus chemical fertilizer (CmDCF), cow manure plus wood ash (CmWa), cow manure combined with wood ash plus fertilizers (CmWaF), chemical fertilizers only (DNF) and unamended controls. Soil samples were collected at 0-20 cm depth at bimonthly intervals during 2018-2019. During the two seasons, 54 nematode genera were identified. Cephalobus, and Heterocephalobus (bacterivores), Labronema (omnivore) and Nygolaimus (predator) were abundant in CmDCF, CmWa, CmWaF, and DNF while Aphelenchus and Aphelenchoides (fungivores) were dominant in all treatments. Principal response curve analysis showed that CmWaF significantly reduced the population of Helicotylenchus, Scutellonema and Rotylenchulus during the 2 nd and 4 th month in the second season. Renyi diversity analysis indicated that CmWaF had higher diversity of omnivores while functional metabolic footprints categorized it as structured in both seasons. Predator-prey analysis suggested that CmWa and CmWaF have the potential to provide suitable conditions for predators, target prey and amplifiable prey biomass. This study provides an insight on the implication of farming practices, on nematode abundance and soil food web in two economically important crops in Kenya. It also provides a basis for exploring the potential role of organic amendments containing cow manure in control of plant parasitic nematodes in maize-beans cropping systems.
Tropical Plant Pathology, 2016
Sweet potato is one of the most important staple food crops consumed in Kenya and throughout Africa but yields are greatly reduced by plant parasitic nematodes (PPN). The aim of this study was to determine the prevalence of PPN in Kenyan sweet potato fields and their relationship with soil and climatic variables. Soil samples were collected from sweet potato fields in Busia, Teso, Kisii, Embu and Makueni counties. Thirteen nematode genera were identified across the five counties with Meloidogyne, Pratylenchus and Rotylenchus being the most prevalent. There was a significant (P <0.05) relationship between PPN abundance and sodium, calcium and iron. Canonical correspondence analysis of climatic variables revealed that the relationship between rainfall and nematode genera was significant (P <0.05) while maximum and minimum temperatures were not significant. This description of PPN assemblages associated with sweet potato in Kenya and their relationship with environmental variables provides a starting point from which appropriate nematode management strategies can be implemented.
Journal of Applied Biosciences, 2018
Objective: To investigate nematode suppression and yield improvement potential of two organic materials; poultry manure and chopped neem leaves in sweet potato production. Methodology and results: A factorial experiment mounted on Randomized Complete Block Design was conducted in 2014 and 2015 at Atebubu and Wenchi, prominent farming communities in the Brong Ahafo region of Ghana. The organic materials were applied on two sweet potato varieties; Apomuden and Santom pona. Poultry manure and neem leaves weighing 100g and 30g respectively were applied per stand. Plant population, nematodes population per 200-cm3 soil at planting and harvest, tuber galls, vine dry matter weight at harvest and yield were analyzed. Significantly, higher (P < 0.05) plant population was recorded at Wenchi compared to Atebubu in 2015. Control plots recorded significantly highest plant parasitic nematodes compared with the poultry manure and neem leaf treatments. Consistently, neem leaf amended plots recorded lowest population levels (67, 68 and 33) % and (84 and 84) % less Meloidogyne spp., P. brachyurus and H. multicintus and Meloidogyne spp., and P. brachyurus were extracted from neem leaf amended Santom pona plots compared with the control of Santom pona at Atebubu and Wenchi respectively. Poultry manure on Santom pona recorded the highest gall index, which was 78.8% more than observed on Santom pona treated with neem leaves. Neem leaf correlated positively with Apomuden and recorded the highest yield in 2014 at Atebubu, which was approximately 93% higher than the control of Santom pona, which yielded 0.9t/ha. The yield of neem leaf on Apomuden was significantly higher (35% and 41%) than neem leaf on Santom pona in 2014 and 2015 at Atebubu and Wenchi respectively. Conclusion and application of findings: Nematode management with synthetic products must be discouraged on grounds of mammalian toxicity and environmental degradation. The use of organic amendments should be encouraged for suppression of nematode population densities, improvement in yield and environmental friendliness. The latter option is sustainable and more importantly, tuber crops produced with organic amendments would be free from chemical residues.
Conservation agriculture (CA) based on the principles of minimum soil disturbance, crop residue retention, and crop rotation has been the focus of intensive research in recent years. A study was carried out to determine the effects of tillage and fertilizer on the population densities of plant-parasitic nematodes in maize. Three tillage regimes, (i) basin planting, (ii) rip line seeding, and (iii) conventional tillage, were combined with four fertilizer regimes: (i) no-fertilizer, (ii) low fertilizer rate, (iii) medium fertilizer rate, and (iv) high fertilizer rate. The experiment was arranged as a split plot in randomized complete block design, replicated three times with tillage as the main plot factor and fertilizer as the sub-plot factor. The study was conducted on finetextured Cambisol soils at Chinhoyi University of Technology farm, Zimbabwe, over two cropping seasons between December 2014 and April 2016. Eight plant-parasitic nematode genera were observed belonging to five groups based on their feeding sites: (i) sedentary endoparasites (Meloidogyne and Rotylenchulus), (ii) migratory endoparasites (Pratylenchus), (iii) semi-endoparasites (Scutelonema and Helicotylenchus), (iv) ectoparasites (Xiphinema and Trichodorus), and (v) algal, lichen or moss feeders (Tylenchus). In both cropping seasons, semi-endoparasitic nematodes were double under rip line seeding and triple under basin planting compared to conventional tillage. Basin planting had higher plant-parasitic nematode richness than rip line seeding. Nematode densities did not have a measurable effect on maize grain yield. Maize grain yield was higher in rip line seeding (37%) and planting basins (52%) than conventional tillage during 2014/15 cropping season. On the other hand, during 2015/16 cropping season, maize grain yield was 78% and 113% higher in rip line seeding and basin planting, respectively, compared to conventional tillage. The results show that under the environmental and edaphic conditions of this specific study site, semi-endoparasitic nematodes were higher under rip line seeding and basin planting compared to conventional tillage. The authors conclude that (i) plantparasitic nematode genera exhibited differential responses to different tillage systems but were not affected by fertilizer application, and (ii) in the present study, maize grain yield response under different tillage and fertilizer regimes was overall not related to nematode population density and composition.
2020
Maize (Zea mays L.) is a significant food security crop in Kenya and it serves as the main source of nutrition and calories among the small-holder farmers. The overall maize yields per hectare have been fluctuating in the past few years posing a great risk to food security. Among the stress factors associated with maize yield loss include plant-feeding nematodes. In this regard, this study was conducted to evaluate the impacts of plant-parasitic nematodes specifically Scutellonema spp. under field conditions on maize performance in Mwea, Kenya. The field trials were laid out in a randomized complete block design with each treatment comprising of four replicates. The treatments included maize plots without nematicide (MPWN) and control plots treated with nematicide. The experiments were conducted in two trials. Soil samples were taken at a 0–20 cm depth at monthly intervals during 2018–2019. During the two trials, MPWN recorded significantly lower plant height and number of leaves pe...
Influence of cover crops and tillage systems on nematode populations in a maize-cover crop intercrop
Archives Of Phytopathology And Plant Protection, 2014
Cropping systems affect the distribution/diversity of soil microorganisms, including soilborne pathogens. In order to examine the effect of the cropping systems on soil nematodes, maize (Zea mays) was intercropped with different cover crops [Glycine max (GM), Macrotyloma uniflorum (MU), Centrosema pascuorum (CP), Cucurbita maxima (CM) and a control experiment with no cover crop (NC)] under different tillage systems [no till, reduced tillage and conventional tillage] to evaluate the effect of the various treatments on nematode population. The treatments were arranged in a split-plot design with three replications each. Tillage was the main treatment while cover crops were applied to subtreatment. In all, nematodes belonging to twenty-two (22) plant parasitic nematode genera were identified. While most of the genera were identified on all the treatments, the interaction of tillage systems and cover crops had significant effect on the population of Xiphinema and Trichodorus only, showing the nullifying effect of some tillage practices on the other nematodes which were significant under crops as only treatments inter alia. This information could be used in nematode management when integrated management systems are being considered for such intercrop mixtures.
Agriculture, Ecosystems & Environment, 2017
Intensification of agriculture, combined with poor agronomic practices have increased the incidence of plant parasitic nematodes (PPN) and other soil pathogens in East Africa, which consequently affects crop productivity in small holder farms. The objective of the study was to assess the effectiveness of farming systems in management of PPN and to recommend the best practice to farmers. Therefore, two field trials were established, one in farmer fields and one on-station, using maize (Zea mays L.), intercropped with beans (Phaseolus vulgaris L.) and in rotation with beans as a sole crop. Organic farming (that received compost, Tithonia diversifolia and neem cake (Azadirachta indica)) was compared to conventional farming (that received fertilizer and nematicide), farmer practice (that received manure, Tithonia diversifolia and wood ash), and a farm with no input application (control). After three years of continuous cultivation, twelve genera of PPN were recovered from soil and/or root samples from the trials. Under inter-and sole-cropping at both sites, the abundance of PPN including Pratylenchus and Meloidogyne were significantly reduced in the organic system compared to the conventional, farmer practices and control. Organic farming was effective in reducing the genera of PPN below the control for a longer period (4 months) compared to conventional farming and farmer practice (2 months). The findings demonstrated the potential of organic farming in the suppression of PPN at the farmer level. Policy development and extension services can therefore consider organic farming as an alternative method in managing soil-borne nematodes in small holder farms in sub-Saharan Africa. However, further studies are required on other crops, in dry areas and the period to top-dress with organic amendments to assure effective suppression of PPN in organic farming.
Influence of some agroforestry practices on the temporal structures of nematodes in western Kenya
European Journal of Soil Biology, 2002
The influence of agroforestry practices on the temporal fluctuation of nematodes was studied in western Kenya. The experiment comprised a fallow phase, which had the following treatments: (1) maize/beans intercropping; (2) maize/beans intercropping with rock phosphate; (3) Crotalaria fallow; (4) Crotalaria fallow with rock phosphate; (5) Crotalaria fallow with rock phosphate (+ Calliandra and napier hedges); and a cultivation phase when all plots were planted to maize and beans. There were strong seasonal fluctuations in the abundance of both free-living and plant-parasitic nematodes. The abundance of plant-parasitic nematodes did not vary among cropping systems during the fallow phase, but varied significantly during the cultivation phase of the experiment. Pratylenchus spp. appeared to be stimulated by the application of phosphorus while Scutellonema spp. had higher populations in the maize crops, which were planted after a Crotalaria fallow. In both the fallow and the cultivation phases, the sampling date had a significant impact on nematode abundance. There were more plant-parasitic nematode species during the fallow phase of the study, but the evenness of the different nematode communities was significantly greater in the cultivation phase of the experiment.
Journal of Asia-pacific Entomology, 2020
The study focused on the ecological analysis of plant and soil nematode communities associated with vegetablesmaize crop sequences in the eastern fringe of Kolkata at Dhapa from December 2011 to April 2014 at a monthly interval. Plant-parasitic nematodes like Pratylenchus zeae, Meloidogyne incognita, Hoplolaimus indicus, Helicotylenchus dihystera, Tylenchorhynchus brevilineatus, Rotylenchulus reniformis, and Criconemoides onoensis were observed in two major cropping sequences of chilli-amaranthus-maize-radish-cauliflower and amaranthus-maize-cabbage-chilli. Among them, R. reniformis was found to be the most prevalent genera with the highest relative prominence value (RPV) of 27.29 followed by P. zeae (20.30) and T. brevilineatus (16.70). The population dynamics of P. zeae revealed the lowest density of the nematode was recorded (26 per 200 cc of soil + 5 g of the root) in March and the highest (634) in September. The variation in the abundances of other PPNs was also noted, and that attributed to the crops in the crop sequence and weather conditions. Low numbers of R. reniformis was found in the maize rhizosphere. The saprozoic nematodes (SNs) maintained higher mean densities (1734/200 cc soil); they were recorded in high numbers in the rainy season as compared to other seasons. No significant differences in the Shannon diversity index (H′), evenness (J) were observed across the growing period. A significant relationship was found between nematode abundance and climatic variables observed. This study provides baseline information on nematodes associated with maize-based cropping system, population abundance, Mylonchulus-SNs relationships, and population fluctuation in response to environmental factors.
Pesquisa Agropecuária Brasileira, 2009
The objective of this work was to assess the effects of conventional tillage and of different direct seeding mulch-based cropping systems (DMC) on soil nematofauna characteristics. The long-term fi eld experiment was carried out in the highlands of Madagascar on an andic Dystrustept soil. Soil samples were taken once a year during three successive years (14 to 16 years after installation of the treatments) from a 0-5-cm soil layer of a conventional tillage system and of three kinds of DMC: direct seeding on mulch from rotation soybean-maize residues; direct seeding of maize-maize rotation on living mulch of silverleaf (Desmodium uncinatum); direct seeding of bean (Phaseolus vulgaris)-soybean rotation on living mulch of kikuyu grass (Pennisetum clandestinum). The samples were compared with samples from natural fallows. The soil nematofauna, characterized by the abundance of different trophic groups and indices (MI, maturity index; EI and SI, enrichment and structure indices), allowed the discrimination of the different cropping systems. The different DMC treatments had a more complex soil food web than the tillage treatment: SI and MI were signifi cantly greater in DMC systems. Moreover, DMC with dead mulch had a lower density of free-living nematodes than DMC with living mulch, which suggested a lower microbial activity.