ABSTRACT
This study investigated the effect of biosynthesized copper nanoparticle from Azadirachta indica extracts on the growth of Vigna unguiculata grown in a soil treated with Sodium Chloride (NaCl) of different concentrations of 0.625g/l, 1.25g/l, 2.5g/l and control and copper nanoparticles of different concentration of 5%, 25% and 50% respectively. Each treatment had four replicates making a total of 52 bags. Five seeds were planted in each bag, and germination readings was taken for seven days. Each bag was keyed with the following letters: A – Control without NaCl and nanoparticles, B, C, D and E for 0.625g/l NaCl only, 0.625g/l NaCl + 5% CuNP, 0.625g/l NaCl + 25% CuNP and 0.625g/l NaCl + 50% CuNP respectively. F, G, H and I represent same concentration of copper nanoparticles for 1.25g/l NaCl treated soil. J, K, L and M also represent same concentrations of copper nanoparticles for 2.5g/l NaCl treated soil At the end of germination studies, copper nanoparticles were applied via foliar spray and readings for plant height, stem girth and number of leaves were taken weekly for 5 weeks The findings of the study were that germination rate of cowpea decreased with increased in NaCl concentration. It also shows that the growth parameters: height, stem girth, number of leaves were also enhanced in this experiment but the effectiveness of copper nanoparticles was reduced with increasing NaCl and copper nanoparticle concentration. For example, at the end of the experiment, treatment E had the highest plant height of 53.78±17.93cm compared to B (18.93±0.63cm), C (20.75±2.22cm), D (20.38±2.14cm) and Control (16.00±1.32cm). The observed PH, microbial analysis, fresh and dry weight of cowpea seedlings show a positive effect of copper nanoparticles on treated plants at low salt concentration but reduce at high salt concentration.
