EFFECTS OF TWO NIGERIAN STRAINS OF MOROCCAN WATERMELON MOSAIC VIRUS (MWMV) ON ELEMENTAL AND PROXIMATE COMPOSITION OF THE LEAVES OF CUCUMEROPSIS MANNII NAUDIN

Abstract

The effects of two Nigerian strains of Moroccan watermelon mosaicvirus (MWMV), (designated as MWMV-cor and MWMV-lag) on the elemental and proximate composition of the leaves of Cucumeropsis mannii were studied. Infected and healthy (control) leaf samples were obtained, pulverized and analyzed for elemental and proximate composition using standard methods described by AOAC. Inoculation with MWMV-cor led to significant increase (p<0.05) in Pb, Co, Fe and Ca compared to healthy sample by 64.03%, 18.18%,12.12% and 11.99% respectively. Values obtained for Zn, Al and Mg, though higher than the healthy control, were statistically insignificant. Conversely, MWMV-cor engendered significant reduction in Cu content by 17.48%, Cd by 53.13% and Ni by 60.61%while values obtained for Mn, Na and K were comparable to the value obtained for healthy control and consequently not significantly different (p<0.05). For MWMV-lag, there were significant increases in Pb content by 39.07%, Cu by 19.54%, Co by 45.45%, Ni by38.46% and Na by 12.18%. Values obtained for Ca, Zn and Mg, though higher, did not differ significantly (p<0.05) compared to healthy sample. On the other hand, Cd and Mn were significantly reduced by 50% and 12.41% by the virus strain while the reduction in Al and K were statistically insignificant. The content of Fe remained unaltered by MWMV-lag infection. With regard to proximate composition, there was an increase in the moisture and fibre contents of C. mannii when inoculated with MWMV-cor compared to healthy control while there were reductions in the amount of protein and lipid in infected leaf tissues. Inoculation of the crop with MWMV-lag led to significantly higher protein content(33.62%) in infected leaf tissue compared with control. Conversely, the virus strain caused insignificant reduction in the moisture, lipid and carbohydrate contents in relation to the control. The implication of this study is that an increase or decrease in the mineral and proximate components of infected C. mannii by MWMV strains is an indication of altered physiology of the crop and could impact negatively on the yield performance and a lowering of potentials of seeds from such harvest for industrial use.