Monday Ahonsi - Academia.edu (original) (raw)

Papers by Monday Ahonsi

Agronomie, 1993

— Various methods were tried for inducing the seeds of Casuarina equisetifolia Forst and Fo... more — Various methods were tried for inducing the seeds of Casuarina equisetifolia Forst and Forst (Casuarinaceae) to germinate faster or in greater numbers than under natural conditions. Percentage germination in untreated seeds (control) ranged from 7 to 16% over an average of 6 days. Some treatments increased the percentage germination by different values up to 62%. The most effective treatment was application of a 0.1 mM solution of GA 3 followed by that of a 2 500 mg dm-3 solution of ascorbic acid, and a 10 mM solution of NaNO 3. Other effective treatments included scarification with concentrated H 2 SO 4 , and application of 0.1 mM IAA solution. Incubating soaked seeds in continuous red light caused the germination to start earlier and also increased the overall germination. Germination was inhibited under continuous blue light, green light and in the dark. Germination was completely prevented in seeds pretreated with a 0.1 mM solution of ABA. Casuarina equisetifolia / germination / GA 3 Résumé — Amélioration de la germination des graines de Casuarina equisetifolia Forst et Forst (Casuarinaceae) par divers traitements avant semis. Divers traitements ont été essayés pour induire les graines de Casuarina equisetifolia à germer plus vite ou en plus grande proportion que dans les conditions naturelles. Le pourcentage de germination des graines non traitées (témoins) variait de 7 à 16%, en 6 j en moyenne. Certains traitements ont amélioré ce pourcentage de valeurs variées, jusqu'à 62%. Le traitement le plus efficace a été l'application d'une solution de GA 3 à 0,1 mM, suivie de celle d'une solution d'acide ascorbique à 2,5 mg dm-3 et d'une solution à 10 mM de NaNO 3. La scarification par H 2 SO 4 concentré et l'application d'une solution de AIA à 0,1 mM a été également efficace. L'incubation des graines imbibées sous lumière rouge continue entraîna une germination plus précoce, et un pourcentage de germination amélioré. La germination a été inhibée en lumière bleue continue, en lumière verte ou à l'obscurité. La germination a été complètement inhibée par un prétraitement par une solution à 0,1 mM d'AIB. Casuarina equisetifolia / germination / GA 3

Cambridge University Press eBooks, Oct 8, 2013

Zenodo (CERN European Organization for Nuclear Research), Apr 1, 2000

Plant Disease, May 1, 2011

African Crop Science Journal, Feb 1, 2002

Three Pseudomonas syringae pathovar glycinea (Psg) strains known to produce large amounts of ethy... more Three Pseudomonas syringae pathovar glycinea (Psg) strains known to produce large amounts of ethylene were tested for efficacy in germinating seeds of Striga hermonthica (Del.) Benth. in a laboratory, as were 312 rhizosphere isolates of non-pathogenic fluorescent Pseudomonas spp. and 38 Bradyrhizobium japonicum isolates. Strains of Psg were 67% as effective as GR-24, and 31 and 38% more effective than ethylene gas (2.5 mg per Petri dish) and root pieces of the best soybean cultivar (SAMSOY-2), respectively. None of the non-pathogenic pseudomonas and rhizobial isolates effectively germinated S. hermonthica seeds compared with Psg strains. Our results indicate that ethylene producing bacterial file:///C|/Documents%20and%20Settings/dberner/My%20Do...20Official%20Site%20(site%20up-dated%20regularly).htm (1 of 11)6/18/2007 7:00:51 AM this publication Bioline International Official Site (site updated regularly) strains can be highly effective in germinating S. hermonthica seeds and suggest that such bacteria have potential as bio-control agents of this parasitic plant in Africa. However, ethylene production by bacteria may be linked with pathogenic ability. This suggests that gene modification and transfer technology may be necessary to exploit the potential usefulness of ethylene-producing bacteria for S. hermonthica control.

Soil Biology & Biochemistry, Nov 1, 2002

The nature of interrelationships between soil pasteurisation, and increased soil N content, on th... more The nature of interrelationships between soil pasteurisation, and increased soil N content, on the severity of Striga hermonthica infection in maize was studied in pot experiments in the screen-house. An initial experiment revealed that there was no significant difference in amount of S. hermonthica infection in maize grown in potted soil collected from Bida (9805 0 N, 6801 0 E) and Ibadan (7817 0 N, 3830 0 E). However, there was 57% increase in amount of S. hermonthica infection and a 68% reduction in maize shoot dry matter when maize was grown in pasteurised soil compared with natural soil. In another experiment, soil steaming significantly influenced the effects of increased soil N fertility (from preceding soybean cv. SAMSOY-2 or application of 90 kg N ha 21) on severity of S. hermonthica in maize. In natural soil, application of N to maize reduced (by 53%) the number of emerged S. hermonthica plants and increased (by 154%) maize dry matter compared with no fertilizer application. In pasteurised soil, application of N to maize increased S. hermonthica severity by 26% and also significantly increased maize dry matter compared with no fertilizer application. The same effects were observed when soybean was used to increase soil N content. Analysis of natural and pasteurised soil revealed only minor differences in composition of K þ , Na þ , Cu, Mn, and Fe, and none of these changes was directly related to S. hermonthica infection in maize. Results of this study indicate that the differences in S. hermonthica infection in pasteurised and natural soil could be attributed to soil biotic factors that reduce S. hermonthica infection in natural soil. The results partly provide an explanation for the wide variation in reports on the effects of N fertilization on severity of S. hermonthica infection and stress the need for understanding the mechanisms of natural reduction in S. hermonthica infection and interactions of these natural mechanisms with other control techniques.

African Crop Science Journal, Sep 21, 2005

European Journal of Plant Pathology, May 20, 2012

ABSTRACT Plant pathogens, especially Phytophthora and bacterial species, in re-circulated irrigat... more ABSTRACT Plant pathogens, especially Phytophthora and bacterial species, in re-circulated irrigation water present a significant health risk to nursery and greenhouse crops. Heat treatment at 95°C for 30 s is one of the most reliable technologies for irrigation water decontamination. The primary objective here was to examine whether the water temperature required to inactivate major pathogens in re-circulated irrigation water can be lowered from 95°C to conserve energy and improve horticultural profitability while reducing environmental footprint. Specifically, we investigated the effect of water temperature on Phytophthora nicotianae zoospore survival in the laboratory and on annual vinca under greenhouse conditions. We also assessed the effect of water temperature on survival of chlamydospores of P. nicotianae, oospores of P. pini, six plant pathogenic bacterial species and Escherichia coli. The zoospores of P. nicotianae did not survive and cause any disease on annual vinca when exposed to 42°C for 12 h or 48°C for 6 h. No chlamydospores of P. nicotianae survived 42°C for 24 h or 48°C for 6 h, nor did the oospores of P. pini at 42°C for 12 h or 48°C for 6 h. In addition, none of the seven bacterial species survived 48°C for 24 h. These results indicate that the required water temperature to eliminate Phytophthora and bacterial species may be lowered substantially from 95°C by longer exposure time, improving the economics and environmental footprint, without sacrificing efficacy of heat treatment.

Frontiers in Insect Science

Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) has become a major threat to maize product... more Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) has become a major threat to maize production in Africa. In this study, six maize genotypes were assessed for their resistance to FAW under artificial infestation in both laboratory and net house conditions. These included two FAW-tolerant hybrids (CKHFAW180294 and CKH191221), two commercial hybrids (WE2115 and CKH10717), and two open-pollinated varieties (ZM523 and KDV4). Larval development time and reproductive potential were assessed on maize leaves in the laboratory and a life table for FAW was constructed. The maize genotypes were also artificially infested with three FAW neonates at two phenological stages (V5 and V7) and reproductive stage (R1) in the net house. Leaf and ear damage scores were recorded on a scale of 1–9. Larval development time varied significantly between maize genotypes with the highest on CKH191221 (16.4 days) and the lowest on KDV4 (13.7 days). The intrinsic rate of natural increase for life tables va...

$Research paper thumbnail of Climate-Smart \u3cem\u3eBrachiaria\u3c/em\u3e Grasses for Improving Livestock Production in East Africa$

Climate change is a global phenomenon with negative impacts severely felt by poor people in devel... more Climate change is a global phenomenon with negative impacts severely felt by poor people in developing countries (Morton 2007). Across many parts of Africa, rural poor communities rely greatly for their survival on agriculture and livestock that are amongst the most climate-sensitive economic sectors. Climate-smart agriculture helps farmers to increase food production, become more resilient to climate change and reduce greenhouse gas (GHG) emissions. The main anthro-pogenic GHGs are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O); they are critically important for regulating the Earth’s surface temperature. Inadequate quantity and quality of feed is a major constraint to livestock production, particularly during the dry seasons across Africa. The overall objective of this inter-institutional program is to increase feed availability in action areas of the target countries in East Africa (e.g. Kenya, Rwanda) by use of climate-smart Brachiaria forage grasses (Rao et al. 201...

$Research paper thumbnail of Fungal Endophytes from the Aerial Tissues of Important Tropical Forage Grasses \u3cem\u3e Brachiaria \u3c/em\u3e spp. in Kenya$

Most, if not all plants in natural ecosystems are symbiotic with mycorrhizal fungi and/or fungal ... more Most, if not all plants in natural ecosystems are symbiotic with mycorrhizal fungi and/or fungal endophytes. This association between plant and fungi is believed to be over 400 million years old when plants first colonized the land (Redecker et al., 2000). These fungal symbionts play important roles on plant ecology, fitness, and evolution; shaping plant communities; and the community structure and diversity of associated organisms. The importance of fungal endophytes in cool season grasses production and effects of endophyte on the livestock health (Examples fescue toxicosis and ryegrass staggers) have been extensively investigated (Smith et al., 2009; di Menna et al., 2012). However, current understanding of fungal endophyte community of warm season grasses (including Brachiaria spp.) and the impact of these endophytes on livestock production is very limited. Therefore, this study aims to analyse fungal endophytes community inhabiting in the aerial tissues of important tropical gr...

Heatmaps of correlation analyses for plant growth promotion experiment showing relationship betwe... more Heatmaps of correlation analyses for plant growth promotion experiment showing relationship between shoot dry weights, root dry weights and total dry weights for the controls and the different test fungal isolates. Colour key shows Pearson's correlation coefficients; red = high, white= mid, and blue= low

The datasets show the fungal endophytes isolated from asymptomatic local Brachiaria grass plant p... more The datasets show the fungal endophytes isolated from asymptomatic local Brachiaria grass plant parts, aerial( leaf and leaf sheath) and root tissues.<br>

Pest Management Science, 2010

Phytophthora nicotianae Breda de Haan is a common pathogen of ornamental plants in recycled irrig... more Phytophthora nicotianae Breda de Haan is a common pathogen of ornamental plants in recycled irrigation systems. In a previous study, annual vinca (Catharanthus roseus Don) inoculated with zoospore suspensions using a CO(2)-pressurized sprayer had less foliage blight than plants inoculated using a hand sprayer. Here, the impact of hydrostatic pressure, agitation and aeration with CO(2) on the survival of P. nicotianae zoospores was examined. Exposure of zoospores to 840 kPa hydrostatic pressure for 8 min or agitation at a mixing intensity (G) of 6483 s(-1) for 4 min at 22-23 degrees C did not kill zoospores, but resulted in viable cysts. Motile and forcefully encysted zoospores of P. nicotianae were equally infectious on vinca or lupine (Lupinus polyphylus Lindl.). Bubbling CO(2) into zoospore-infested water at 110.4 mL (0.2 g) min(-1) for 5 min caused 81% reduction in the number of germinated zoospores. Pressure at 630 kPa (16.3 g CO(2)) or 70 kPa (3.85 g CO(2)) facilitated CO(2) injection and shortened the zoospore inactivation time to 30 s. When air was bubbled through the suspension, germination was similar to the control. Exposure to CO(2) killed P. nicotianae zoospores in water. Neither pressure nor agitation had an effect on zoospore viability or infectivity. Based on results of this study, the authors designed a recycling CO(2) water treatment system that is currently under evaluation.

European Journal of Plant Pathology, 2005

Stagonospora convolvuli LA39, an effective biocontrol agent of Convolvulus arvensis (field bindwe... more Stagonospora convolvuli LA39, an effective biocontrol agent of Convolvulus arvensis (field bindweed) and Calystegia sepium (hedge bindweed) produces phytotoxic metabolites leptosphaerodione and elsinochrome A. Stagonospora isolate 214Caa produces the toxin cercosporin. If toxic metabolite production is not linked to the pathogenic ability of the fungus on bindweeds, selection of aggressive strains with limited or no production of the metabolites would reduce any perceived risk of using strains of the fungus as a mycoherbicide. Therefore, 30 isolates of Stagonospora sp. including LA39 and 214Caa were characterised for aggressiveness on both bindweeds, and production of the three metabolites. Nine isolates were more aggressive than LA39 on both bindweeds. Classification of isolates based on metabolite type agreed largely with previous similar characterisation based on polymerase chain reaction-restriction fragment length polymorphism of internal transcribed spacer of ribosomal DNA. Cercosporin producers produced neither leptosphaerodione nor elsinochrome A and together with isolates that produce none of the three metabolites, were less pathogenic on bindweeds. Conversely, there was a positive correlation between elsinochrome A and leptosphaerodione production, and each was positively correlated with aggressiveness of isolates on both bindweeds. Generally, any isolate where elsinochrome A was not detected was not aggressive on any of the two bindweeds. This probably implies that selecting elsinochrome A-negative, but aggressive Stagonospora strain(s) may be difficult. However, aggressive isolates may not produce elsinochrome A in planta at levels that could constitute any risk in the environment. In a preliminary attempt to determine the levels of elsinochrome A and leptosphaerodione produced in diseased bindweeds, none of the toxins was detected in Stagonospora infected bindweed leaves. Detailed investigation focusing on the detection and quantification of in planta production of elsinochrome A by Stagonospora isolates, and determination of the fate of elsinochrome A in the environment, and its relationship with leptosphaerodione may be essential. Similarly, development of molecular tools to monitor the mycoherbicide following field application is vital.

Crop Protection, 2003

High variation in results from Striga hermonthica experiments is common. The cut-root assay for i... more High variation in results from Striga hermonthica experiments is common. The cut-root assay for in vitro screening of host and non-host plant cultivars for germination of S. hermonthica is particularly insensitive. In this study, some factors of the cut-root technique that could effect significant variation in germination percentage of a population of S. hermonthica seeds induced by the same crop cultivar were studied. It was found that excised pieces of both root and stem of maize (hybrid var 8338-1), cowpea (var IT81D-994) and soybean (var TGx 1448-2E) stimulated the germination of S. hermonthica seeds. Germination percentages obtained with maize and cowpea stem pieces were significantly higher than those produced by root pieces. Moistening filter paper on which conditioned Striga seeds were subjected to germination stimulants with 5 ml of distilled water resulted in significantly higher germination of the parasite's seeds induced by stimulants from both maize and soybean, than adding 3 ml of water, regardless of the plant part tested. Starting germination stimulant extraction immediately after cutting plant parts gave significantly higher germination percentage of S. hermonthica seeds than starting 3 h later, regardless of crop species and plant part tested. Conditioning S. hermonthica seeds and subsequent extraction of germination stimulant with non-sterile water generally resulted in higher germination percentage of S. hermonthica seeds than with sterile distilled water. These results are discussed and suggestions made about how to reduce variability of results of the cut-root method of in vitro assaying of germination stimulant production by hosts and trap crops of S. hermonthica.

Agriculture, Ecosystems & Environment, 2004