Evaluation of Cowpea Genotypes for Resistance to <i>Fusarium redolens</i> in Uganda

Abstract

<i> Fusarium redolens </i> , a virulent fungus which causes damping off, leaf yellowing, wilting and root rots has recently been devastating cowpea fields in Uganda. This study aimed at identifying cowpea genotypes that are resistant to <i> Fusarium redolens </i> . Therefore, ninety cowpea genotypes were evaluated two times against a highly virulent <i> Fusarium redolens </i> (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 <i> Fusarium redolens </i> . All the released varieties tested (SECOW 1 T, SECOW 2 W, SECOW 3 B, SECOW 4 W and SECOW 5 T) had moderate resistance to <i> Fusarium redolens </i> . 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 <i> Fusarium redolens </i> 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 <i> Fusarium redolens </i> resistance in Uganda.