Abiodun O. Claudius-Cole

Differential effect of hot water treatment on whole tubers versus cut setts of yam (Dioscorea spp.)

BACKGROUND The use of thermotherapy or hot water treatment (HWT) is recommended for the management of plant-parasitic nematodes and other pathogens for a range of planting material, especially vegetatively propagated crops including yams, Dioscorea spp. The sprouting (germination) and consequent viability of yam following HWT, however, appear to be influenced by the post-treatment method of planting (whole or cut setts) and cultivar. The present study was established to evaluate the sensitivity of the most popular yam cultivars in Benin and Nigeria, West Africa, to HWT at 50-53 degrees C for 20 min. RESULTS Sprouting of both setts and whole tubers of most cultivars was affected by HWT. Across experiments, 47% of HWT material, compared with 61% of non-HWT material, sprouted over 8 weeks. When cut into setts, 41% of HWT or untreated tubers sprouted, compared with 72% of whole tubers. Whole, untreated tubers had highest sprouting rates (84%), and setts following HWT had the lowest (38%). Yam planting material was also not completely free of parasitic nematodes following HWT. The reaction to HWT or cutting was highly cultivar specific. CONCLUSION Yam cultivars vary in their sensitivity to hot water therapy. Care is therefore advised in selecting yam cultivars for HWT, especially when using cut setts.

Economic Analysis of Commercial Seed Yam Production Systems in the Sub-humid Ecologies of the River Niger

Published studies to date have suggested that seed-yam (Dioscorea rotundata) production in Nigeria using minisett (∼0.025 kg) technology or an adapted form of the technology using larger setts (0.08 to 0.1 kg) was not profitable. But these studies were often conducted under artificial conditions where labor inputs may have been inflated. This paper describes the results of a questionnaire-based survey designed to explore the economic performance of seed-yam producers in the Ilushi hinterland area of Nigeria, along the western bank of the River Niger. It is the first economic study of this important source of seed yam. Farmers in this area specialize in seed-yam production via two techniques: the use of small whole tubers (0.05 to 0.1 kg) and setts (cut pieces of tuber) of 0.12 to 0.15 kg. Results suggest that seed-yam production is profitable in the area using both systems, with gross margins (revenue – costs) of between Naira 23,395 and 61,375/ha (or US

Facilitating healthy seed yam entrepreneurship in the Niger River system in Nigeria The value of 'Research into Use'

175 to

Plant-Parasitic Nematodes and Food Security in Sub-Saharan Africa

458/ha).

Effect of fungi–termite interaction on the chlorophyll content of three rice varieties grown on ultisol soil of Ikenne, south-west Nigeria

This paper explores the results of a programme designed to facilitate entrepreneurship centred on healthy seed yam (Dioscorea rotundata) production on the eastern bank of the River Niger. Ware yam farmers residing along the eastern bank, upstream of the Niger/Benue confluence, source their planting material from towns such as Ilushi in Edo state, which involves significant travel and expense. The project encouraged 10 ware yam farmers living in Edeke village (Idah local government, Kogi state) to specialize in healthy seed yam production by employing the adapted yam minisett technique (AYMT). This employs a sett size of around 80–100 g treated with a joint insecticide and fungicide dip. The treated setts are planted directly into the field, not first planted into a nursery as with the yam minisett technique (YMT). The Edeke farmers received a loan from the Diocesan Development Services (DDS) to employ the AYMT to produce healthy seed yams on a significant scale. However, while sales of seed yam by four of the farmers generated a significant and positive gross margin, six farmers opted to plant their seed yams in the subsequent season (2012) to produce ware yams. This paper presents some of the results, and discusses the decisions taken and the dilemmas faced by the farmers in the production of seed and ware yam and the possibility of initiating and developing new markets for seed yam in the Idah area.

Effect of Heterodera sacchari on growth and yield of selected upland NERICA rice in Nigeria

Sub-Saharan Africa (SSA) is a region beset with challenges, not least its ability to feed itself. Low agricultural productivity, exploding populations, and escalating urbanization have led to declining per capita food availability. In order to reverse this trend, crop production systems must intensify, which brings with it an elevated threat from pests and diseases, including plant-parasitic nematodes. A holistic systems approach to pest management recognizes disciplinary integration. However, a critical under-representation of nematology expertise is a pivotal shortcoming, especially given the magnitude of the threat nematodes pose under more intensified systems. With more volatile climates, efficient use of water by healthy root systems is especially crucial. Within SSA, smallholder farming systems dominate the agricultural landscape, where a limited understanding of nematode problems prevails. This review provides a synopsis of current nematode challenges facing SSA and presents the opportunities to overcome current shortcomings, including a means to increase nematology capacity.

Phenology of Tick weed (Cleome viscosa L.) and its interaction with okra (Abelmoschus esculentus (L.) Moench) and Melodoigyne incognita

The effect of fungi–termite interaction on three rice varieties was conducted in a screen house at the Africa Rice Center (AfricaRice) Ibadan, Nigeria. Of the 10 fungi species (Fusarium verticilloides, Trichoderma sp., Aspergillus niger, Aspergillus flavus, Macrophoma sp., Neurospora sp., Botryodiplodia theobromae, Penicillum sp., Rhizopus sp. and Sclerotium rolfsii) isolated from termites, soil and rice plants, F. verticilloides, Trichoderma sp. and B. theobromae were used for the interaction study. Each fungus was inoculated singly and in combinations with termite into the root of each rice variety in potted soil. Leaf samples were taken to measure the chlorophyll content which is a major parameter to estimate effect of termite–fungi interaction. The chlorophyll content of the inoculated rice plants was significantly reduced when compared with the control. Fungi interaction with termite had significant reduction on the chlorophyll content. The synergistic relationship between the fungi and the termite was discussed.

Tropical cover crops for the management of the yam nematode, Scutellonema bradys

Pot and field trials were conducted in 2012 and 2013 cropping seasons in Nigeria to determine the damage of Heterodera sacchari on the growth and yield of upland New Rice for Africa (NERICA) derived from hybridisation of Oryza sativa and O. glaberrima. NERICA rice (NR) cultivars selected were NR1, NR2, NR3, NR8 and NR14. In screenhouse experiments, rice seedlings were inoculated with 2500, 5000 and 10000 eggs and second-stage juveniles of H. sacchari, three weeks after sowing. In addition, two consecutive field experiments were carried out on a naturally infested field. Data on plant growth, yield, and final H. sacchari population densities were taken at the end of the experiments. Significant reductions of 34, 60 and 78% were observed in plant height, fresh root and total seed weights, respectively. Infected plants also produced chlorotic tillers and showed delayed panicle emergence. In field experiments, rice yield was reduced by approximately 50 and 85% in the first and second cropping seasons, respectively. Nematode population densities in soil and roots of rice plants increased significantly in infected plants compared to the controls. The results of this study indicate that H. sacchari is a serious pathogen of susceptible upland NR cultivars and may cause total crop failure when NR is continuously cultivated in cyst nematode infested fields.

Management of Meloidogyne incognita in yam-based cropping systems with cover crops

Abstract Cleome viscosa is an emerging weed with the potential of interfering with okra and influencing pests of okra. Screen house studies were conducted on the phenology of C. viscosa, its interference with okra and its interaction with root-knot nematode-infected okra. Seedlings of C. viscosa were monitored in pots for growth, yield and dry matter accumulation for 14 weeks. C. viscosa was planted with okra at densities 0, 2, 4, 6, 8 and 10 weeds per okra plant and observed for 11 weeks. Data were collected on growth, yield and dry matter of okra. Plants were inoculated with 2,500 M. incognita eggs per pot while control plants were not inoculated. C. viscosa attained 91.7 cm height and accumulated 7.8 g/plant biomass at 14 weeks after planting. The percentage reduction in okra plant height, plant dry weight and fruit yield due to interference at lowest cleome density (2 plants/pot) was 33.7, 83.6 and 82.1%, respectively. Nematode reproductive factor was significantly lower for okra alone (4.9) compared to okra with cleome (7.6). This study shows that C. viscosa is a fast-growing weed that suppressed the performance of okra even at low density, is a good host to M. incognita and increased the population of the nematode in soil.

Characterization of Meloidogyne species and the reaction of tomato Solanum lycopersicum L. cultivars to Meloidogyne incognita and Meloidogyne javanica

ABSTRACT Yam tuber dry rot caused by Scutellonema bradys results in the reduction of tuber quality. Studies were conducted on the effect of intercropping cover crops with yams on nematode damage to tubers. Eleven cover crops were intercropped with yams in pot screen house and field experiments. Plants were inoculated with S. bradys in water suspension in pots and by incorporating infected yam peels into soil around plant roots in field experiments with un-inoculated plants serving as control. The experiments were factorial with six replications per treatment in pot and four in field experiments. In pot experiments, populations of S. bradys recovered from tubers and nematode damage were lower in yam tubers intercropped with Tagetes erecta, Aeschynomene histrix, Stylosanthes guianensis, Mucuna pruriens and Pueraria phaseoloides compared to where no cover crops were intercropped with yams. Conversely, S. bradys populations from pots with Crotalaria ochroleuca, Crotalaria juncea, Centrosema pubescens, Cajanus cajan and Lablab purpureus were similar to Vigna unguiculata, a known host of S. bradys. The use of A. histrix, T. erecta and S. guianensis, M. pruriens and P. phaseoloides offers promise for inclusion in yam-based cropping systems as a measure for S. bradys management in yam production.