Determination of chlorophyll content, carbonic anhydrase activity, bio-productivity and composition of groundnuts under five Zinc Oxide (ZnO) applications

The low level of carbonic anhydrase activity in groundnut grown on soil with limited zinc (Zn) content is one of the factors responsible for low yield in groundnuts in Nigeria. Hence, this study was carried out to further strengthen the significance of Zn in enhancing photosynthetic processes through carbonic anhydrase activity. It also determines how Zn application affects biochemical components, growth, yield and composition of Arachis hypogaea cv SAMNUT 22. In this study, a potexperiment was performed to investigate the effects of five concentrations of Zn applied in form of zinc oxide (0.00, 1.00, 2.00, 3.00 and 4.00 gL-1ZnO) on the chlorophyll, carbonic anhydrase activity, bio-productivity and proximate composition of groundnut seeds. Data on the aforementioned parameters were subjected to One-way Analysis of Variance and means separated using Duncan Multiple Range Test at p<0.05. The results showed that total chlorophyll in leaves increased with increasing concentration of ZnO and hence the lowest and highest chlorophyll were recorded in 1.00 gL-1 and 4.00 gL-1 respectively. Carbonic anhydrase, after flowering showed a marked improvement with increases in ZnO application compared to the control. The bio-productivity in terms of growth components and yield attributes were respectively enhanced when the concentration of the applied ZnO is increased. Carbohydrate, protein and ash content of harvested seeds were significantly higher (p<0.05) in ZnO treated plants when compared to the control. The results indicated that application of ZnO at 4.00 gL-1 is considered optimum for enhancement of biochemical, growth and yield attributes of the studied groundnut. Also, the reported concentrations of ZnO showed positive influences only on carbohydrate, protein and ash contents of the harvested seeds.