Changes in morphology and yield attributes of Nigella sativa L. by copper (Cu) induced toxicity

The present study was conducted to evaluate the impact of Cu-induced toxicity on the growth, yield parameters, and Cu accumulation in the seeds of black cumin (Nigella sativa L.) plants. In this experiment, plants grown in earthen pots filled with 3 kg of garden soil were contaminated with different dilutions (1.5, 2.0, 2.5, 3.0, 3.5, 4.0) of Cu in millimoles (mM), except for the control. Growth, yield, and Cu bioaccumulation parameters were recorded and analyzed at the harvesting stage. Results revealed that all doses of Cu show a considerable negative effect on the growth and yield parameters of black cumin as the concentration of Cu increased in the soil and reduced all of the growth parameters significantly (p <= 0.05). With each Cu dose, the levels of chlorophyll a and b in the tissues of fresh leaves decreased significantly (p <= 0.05). Fruit and seed yield also decreased significantly (p <= 0.05) from the lower to the higher dose of Cu (1.5 mM to 4.0 mM). Cu bioaccumulation levels in the seeds of all treated plants (Control to 4.0 mM Cu) are under the threshold limit for Cu set by the Food Safety and Standards Authority of India (FSSAI) and World Health Organization (WHO) for spices and are safe for human consumption. Finally, due to the low seed yield in Cu-contaminated soil, it is advised to farmers that Nigella sativa should not be grown in Cu-contaminated soil to avoid economic loss.