Selected micronutrients effect on growth, development, and yield of black nightshade (Solanum nigrum)

Abstract Black nightshade (Solanum nigrum) is an important indigenous leafy vegetable consumed in sub‐Saharan Africa. The species is an important source of micronutrients for medicinal purposes. A controlled experiment was conducted at the University of KwaZulu‐Natal, Pietermaritzburg, South Africa, to investigate the effect of zinc and boron applications on the growth, development, and yield of black nightshade. Each micronutrient (zinc and boron) was applied at five different concentrations, namely, 100 (T1), 200 (T2), 300 (T3), 400 (T4), and 500 (T5) ppm, including a control (T0) (distilled/high pressure liquid chromatography water spray), giving a total of six treatments. Treatments were arranged in a complete randomized design (CRD) with three replications, giving a total of 18 experimental units (pots). After 14 days of transplanting, the treatments were applied through foliar spraying three times over 24 h with an 8‐h interval between each spraying event. Data collection started 14 days after transplanting, and thereafter, measurements were taken fortnightly. At harvest (70 days after transplanting), fruit number, fresh shoot weight, dry shoot weight, root fresh mass, and root dry mass were determined. The results showed significant growth and yield differences with respect to the different concentrations of zinc and boron (p < 0.05). The application of 500 ppm of boron performed significantly better than all other treatments, viz., zinc, and control across the measured variables (p < 0.05). Therefore, it is concluded that the application of boron at 500 ppm was found to be effective in enhancing plant growth and higher fruit yield (45 fruits) of black nightshade.