Physio-Chemical Properties Responses of Six Fonio Genotypes (Digitaria exilis and D. iburua) Subjected to Drought Stress Conditions

The cultivation of fonio in the Western Africa has been greatly hindered by the low amount of rainfall. Crop failure due to drought has been widely reported in Nigeria, which has led to research on different crops with paucity of information on fonio. The present study evaluated six drought genotypes of fonio to determine their physiological and biochemical responses under drought stress conditions. Fonio seeds were planted for a period of 3 weeks and subjected to drought. WUE decreased under drought stress particularly in the P21 genotype, while the RSR significantly increased for all evaluated genotypes. Drought stress seems to enhance the lipid peroxidation and free amino acid activities in the 6 evaluated genotypes, whereas it reduced the proline activities in 4 out of the 6 genotypes. At the early and the late stage, the highest lipid peroxidation was recorded in P25 and P21 respectively. The SOD activities varied at the early and the late stage under drought stress conditions, particularly for the P25, which showed higher level of SOD activities (= 10 folds higher than the control group at the late stage). The activities of CAT and GR for all genotypes studied were not affected by these stressful conditions. However, the APX activity was preferentially reduced in some genotypes, while the remaining ones were unchanged. In conclusion, difference in the physiochemical responses to drought reflects the differences in the ability of the genotypes to withstand varying degrees of drought. The increase in SOD activities might be a frontline defence to counter the increase observed in lipid peroxidation content caused by the reduction in CAT activities under droughtconditionsn.