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Evaluation of Cowpea Genotypes for Resistance to Fusarium redolens in Uganda

Cowpea is the most important legume in the Eastern and Northern region of Uganda where both its leaves and grains are used as food. Its cultivation in Uganda is constrained by many factors. In this paper, the authors aimed at screening cowpea genotypes against Fusarium redolens, a root rot causing pathogen that was found to be the most devastative to cowpea in greenhouse condition.

In the study, ninety cowpea genotypes were evaluated two times against a highly virulent Fusarium redolens (isolate from Zombo in Paidha district) in the screen house in 2016. Genotype effect was highly significant (P < 0.001) for root rot severity. Based on the Index of Susceptibility (IS), three genotypes (Asontem, Dan1 LA and IT89KD-88) remained resistant (IS < 3.5) over the two screening periods, 72 moderately resistant (3.5 ≤ IS < 6.5) and 11 susceptible (IS ≥ 6.5). Resistance was found to be enhanced by presence of lateral roots above or at the ground level. Further results suggested a difference in genetic control of resistance to root rots and seed rots caused by Fusarium redolens. All the released varieties tested (SECOW 1T, SECOW 2 W, SECOW 3 B, SECOW 4 W and SECOW 5 T) had moderate resistance to Fusarium redolens. Correlation analysis revealed root rot severity was strongly correlated to disease incidence (+0.64, P < 0.001), to proportion of plants with lateral roots (-0.56, P < 0.001), to amount of leaf chlorophyll (-0.53, P < 0.001) and to proportion of plants that died prematurely due to Fusarium redolens infection (+0.45, P < 0.001). No significant correlation was detected between root rot severity and proportion of plants that germinated. The established resistance could be exploited for improvement of farmer preferred cowpea varieties towards Fusarium redolens resistance in Uganda.

In addition, field evaluation studies are recommended as it is essential to evaluate the stability of this resistance in varying environments especially under severe stresses to avoid disease escapes.

Article by Roy Wanjala Namasaka, et al, from Uganda.

Full access: http://mrw.so/RPmeo

Image by MelindaChan ^..^, from Flickr-cc.

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