Assessment of Morphoanatomical Modifications in Cucurbita pepo L. in Response to Combined Drought and Nickel Stress

Background: Nickel (Ni) is a toxic heavy metal and causes human health risks as well as plant abnormalities. The present study aimed to determine morpho-anatomical features of Cucurbita pepo L. var. fastigata under combined drought and Ni stress in greenhouse experiment. Methods: Seedlings were treated with four irrigation levels to induce drought stress 14 ml, 11.2 ml, 8.4 ml and 5.6 ml (abbreviated as S0, S1, S2 and S3) along with 25 ppm of Nickel. Results: The results were analyzed after 5th and 10th days and data revealed that seed germination rate and stem diameter was significantly (P≤ 0.05) increased while stem length, root length, root diameter, the number of secondary roots, leaf area, fresh weight, and dry weight were decreased. Among anatomical characteristics epidermis, xylem, phloem tissues, cortex, trichomes, medullary rays, endodermis, pericycle, palisade, mesophyll cells, and stem mid rib were adversely affected under water stress (S1 and S2) while plants under combined Ni stress showed significant (P≤ 0.05) reduction in cortex diameter, and increase in epidermis thickness, vascular bundles size except for S3 treatment level. Conclusion: It was concluded that combined drought and Ni stress positively affected the morphological features (roots, stem length, and leaf area) of the Cucurbita pepo plant as compared to separate water and Ni stress, preventing plant wilting.