Bioherbicide Effect of Effluent from Processed Manihot esculentus Tubers

Abstract

Effluents from processed bitter cassava (Manihot esculentus) tubers as bioherbicide was applied on the leaves of Beans, Broom weed, Maize, and Itch grass and investigated. Quantitative and qualitative characterization of microorganisms (bacteria and fungi) was done both in effluent and test soil. Mineral analysis using atomic absorption spectrum (AAS), cyanide quantification in the effluent, and quantification of chlorophyll (a and b) from the leaves of test plants (Beans, Broom weed, Maize, and Itch grass) were carried out. The result from the microbial characterization of effluent, test soil, and control soil revealed the effluent had the highest microbial load. The isolated bacteria were Staphylococcus spp, Bacillus spp, Lactobacillus, and E. coli. Test soil had 16.13% Staphylococcus, 9.68% Bacillus spp, 16.13% Lactobacillus, and 6.45% E. coli. The isolated fungi were Saccharomyces, Mucor, and Aspergillus in the effluent, while Saccharomyces and Mucor were in the test soil and only Aspergillus in the control soil.The fungal count revealed a high total viable count (TVC) in the effluent (7.0×104 cfu/ml) followed by test soil (6.6×104 cfu/ml) while control soil had the least (4.5%×104 cfu/ml). Cyanide analysis of effluent revealed 1.0 mg/ml, while metal analysis revealed potassium (40.221 mg/kg), sodium (32.009 mg/kg), Manganese (0.057 mg/kg) and Copper (-0.004mg/kg).The chlorophyll(a and b) concentration expressed in µg/mlof the experimented plants (Beans, Broom weed, Maize, and Itchgrass) further revealed a significant (p≤0.05) decrease concerning the volume of effluent applied (50 ml and 25 ml).Dicotyledonous plants; beans (0.461 + 0.025 and 0.609 + 0.013chlorophyll (a) compared to a control of 7.698+ 0.100.Chlorophyll(b) on the other hand revealed 5.507 + 0.141and 11.599 + 0.282 when compared with control of 16.426 + 0.016). Broom weed (0.291 + 0.071 and 0.457 + 0.068 for chlorophyll (a) when compared to the control with 0.595 + 0.071 and 1.549+0.141 and 1.683+0.353 for chlorophyll(b) when compared to the control with 22.252 + 0.282. Other plants analyzed revealed various significant (p≤0.05) decreased levels of chlorophyll (a and b). All the results revealed this effluent may be selectively used as a potential bioherbicide especially when applied to the leaves.