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Predicting Endophytes Contribution In vivo in Napier Grass Accessions’ tolerance against Ustilago kamerunensis Using In vitro Strategies

296-303Full Text

DO Omayio *, SI Ajanga , JV Muoma DMW. Ochieno, FN Muyekho, B Mukoye and RK Leitich

Abstract: Two completely randomized laboratory assays were carried out at the plant pathology section of the National Agricultural Research Laboratories- Kabete in Nairobi Kenya. The aim of the studies was to determine the abundance of endophytes among an initially selected and presumed tolerant napier grass accessions to head smut pathogen and to decipher their possible synergistic or individualistic contribution to the accessions asymptomatic response to the disease challenge. The analyzed Shannon diversity indices results indicated that the abundance of fungal endophytes was unequal with some exceptions. Moreover, low inhibition percentages were obtained of the morphotypes in dual cultures in vitro with the pathogen, besides most of their interactions favouring the luxurious growth of the pathogen. Therefore, direct role of the endophytes to the tolerance of the accessions seems non-existent if not minimal. However, heightened hormonal secretions like auxins by the crop need to be investigated to determine whether the endophytes are enhancing its production to enable the plants tolerate the pathogen damage through compensatory growth strategies. Keywords: Endophytes, Ustilago kamerunensis, Abundance, Inhibition, Dominance.

Differences in wheat grain yield under varying seed rates to within and inter seasonal temperature Variation

304-307Full Text

Abdalla MG* and Mohamed SM

Abstract: Four wheat cultivars were studied at the Gezira Research Station Farm, Wad Medani, Sudan, for two seasons (2004/05-2005/06) in split-split plot design, where sowing dates occupied the main plots, seed rates in sub-plots and the cultivars in the sub-sub plots with four replicates. The First objective of this study was compared field performance of the cultivars under varying temperatures. Second one was assessed within season and between seasons variations in grain yield. The results show that three cultivars Elneilain, Debeira and Argine were obtained high grain yield in the early heat stress (early season) while, the cultivar Condor was best in the late heat stress. Moreover, the variations in grain yield were more within season than between seasons under varying temperatures. Population densities (seed rates), under varying temperatures, had significant effect on grain yield but the interaction between seed rates and cultivars had no significant effect. Keywords: Bread wheat, Sowing date, Seed rate, Gezira.


308-316Full Text

BC Mangeni*, MM Abang, H Awale, CN Omuse, R Leitch, W Arinaitwe , B Mukoye, JD Kelly and HK Were

Abstract: Common bean (Phaseolus vulgaris L) is an important food legume crop in Kenya as a major source of protein in human diet. The yield is 530 kg ha-1 and the country production is estimated at 529,265 tons. Bean production is declining in Kenya due to various abiotic and biotic factors. Virus diseases are a major yield reduction factor in bean production. Among the viruses infecting beans, Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are most wide spread. The current status of BCMV in western Kenya is not well documented. The main objective of this study was to carry out a diagnostic survey for Bean common mosaic disease (BCMD) in bean growing areas of western Kenya, characterize its causal agent and evaluate host resistance to BCMV and BCMNV. BCMD incidence varied across the AEZs being high in LM2 (17.90%) and lowest in LM3 (3.75%). Pathogenic characterization studies of isolates of BCMV and BCMNV on common bean collected from western Kenya revealed the presence of three pathogroups PG IV, PG VI and Pathogroup VII. Serological analysis of the samples revealed mixed infections of BCMV and BCMNV in common bean. Positive samples for BCMV and BCMNV detected by enzyme linked immunosobent assay, ELISA, were categorized into 3 isolates X, Y and Z. Two new pathogroups IV and VII belonging to BCMNV are shown to occur for the first time in the region. The presence of two SCAR DNA markers SW13 and SBD5 associated with the dominant I gene and recessive bc-12 resistance gene respectively to BCMV in twelve lines from the popular Andean Diversity Panel (ADP) from Kenya confirmed the presence of bc-12 gene in 75% of the lines whereas the I gene was present in only 3 (25%) of the lines. Keywords: Common bean (Phaseolus vulgaris L), Bean common mosaic disease, Bean common mosaic virus, Bean common mosaic necrosis virus, Pathogroups, Screening.

Estimating Iranians Consumers’ WTP for Hashemi Organic Rice

317-322Full Text

Mohammad Kavoosi-Kalashami* and Morteza Heydari-Shalmani

Abstract: Health, food safety and the environment are the main reasons for tendency to consume organic products, the entire world especially the industrialized countries are seeking for agricultural system to supply human food sources that are economically renewable and socially desirable, however the organic agriculture is an integrated and safe systematic agricultural production system that does not conflict with environmental and economic benefits and is suitable for the production of healthy food with no contaminants. Present study investigates the Iranian consumers’ willingness to pay (WTP) for organic product of Hashemi rice based on the use of Heckman two-stage open-end valuation approach. The study results showed that the variables of education, household income, individuals’ attitudes towards organic products and consumption frequency of rice per week had a significant and positive statistical effect on the urban consumers’ WTP for Hashemi organic rice. Also, the average WTP for a kilogram of organic rice is 13.6% higher than that of the ordinary rice. Keywords: Tendency to pay, Organic rice, Urban households, Heckman method.

Towards The Management of Napier Head Smut; Using In vitro Approaches to Decipher Possible Role of Antibiosis Resistance in Selected Napier Accessions

323-329Full Text

DO Omayio*, SI Ajanga, JV Muoma, FN Muyekho and I Kariuki

Abstract: A glasshouse factorial experiment in completely randomized design coupled with laboratory assays were conducted at Kenya Agricultural and Livestock Research Organization-Muguga south and National Agricultural Research Laboratories-Kabete Kenya. The study was conducted with the specific objective being to decipher the possible strategy of resistance involved in napier grass accessions’ management of head smut disease through host plant resistance. The sample study entailed selected asymptomatic and molecularly screened napier grass accessions which had been acquired from ILRI germplasm bank. Laboratory assays were conducted where the purposively sampled accessions’ crude extracts were used from second harvest point to determine their effect on the pathogen’s lag phase in vitro. Crude extracts from accession 16805 and Kakamega 1 resistant variety exhibited the longest lag phases of 18.5 (R2 = 0.9969) and 18.2 (R2 = 0.9969) hours respectively, whereas Clone 13 a susceptible variety and blank control exhibited the shortest lag phases of 17.1 (R2 = 0.9977) and 15.3 (R2 = 0.9965) hours respectively. The results indicated that the strategy of resistance used by the accessions to combat the pathogen establishment seems antibiosis. However, further elucidation of the observed resistance phenomenon will be critical through biochemical methods and fluorescence microscopy to fully optimize on the accession’s resistance as potential breeding candidates for superior clones towards effective management of the napier head smut disease. Keywords: Antibiosis, Head smut, Napier grass, Assay, Antixenosis.