Heavy metal contamination of the environment is increasing alarmingly due to increased anthropogenic activities. Among the various heavy metals, cadmium is a highly toxic heavy metal requiring urgent removal from soil. Strobilanthes alternata, a herbaceous terrestrial plant, has been reported to be an excellent plant for Cd phytostabilization. The present study investigated the effect of 25 ppm of 6-Benzylaminopurine (6-BAP) foliar sprays on the modulation of the physiological responses and elemental constitution in S. alternata grown in 250 mg/kg CdCl2 treated soil. The administration of 6-BAP effectively relieved the toxic effects of Cd by enhancing the total soluble sugar and alkaloid content of leaves by 56 and 250%, respectively, the total soluble protein content of roots by 27%, the phenolic content of roots and leaves by 9 and 10% respectively, and flavonoid content of roots and leaves by 53 and 6% respectively, in Cd-stressed S. alternata. Moreover, the 6-BAP-induced elevation of the thiol content of roots indicated amplified sequestration of Cd, thereby inflicting less damage to the aboveground portions of Cd + 6-BAP-treated plants. This inference was confirmed by SEM-EDX analysis, which revealed high Cd weight percentages in the roots of Cd + 6-BAP-treated plants. The ionomics and CHNS analysis confirmed that 6-BAP ascribable alterations in the elemental content and distribution helped the plant tolerate the adverse effects of Cd in S. alternata. Thus, the 6-BAP treatment could be used as a suitable and ecologically acceptable amendment to reduce Cd-induced damage and enhance the Cd phytostabilization potential in S. alternata.

Meloidogyne incognita is a potentially harmful member of the root-knot nematode family that is capable of impairing plant growth and lowering crop production. They harm their host plants by restricting nutrition, changing cell physiology, dampening the defense system, causing mechanical damage and structural changes, and finally leading to plant death. The aim of this study is to investigate how vermicompost treatment influences the ability of tomato plants to combat free radicals and the changes in their structural components under nematode stress. Tomato seedlings were subjected to vermicompost extract treatment and allowed to germinate in earthen pots. Following germination, they were transplanted into individual pots and exposed to freshly hatched juveniles of Meloidogyne incognita. After a 45-day period, the plants were harvested, and various physiological aspects (such as free radical scavenging capacity and electrolyte leakage) and structural components (including carbohydrate content, elemental composition, and functional groups) were analyzed. Additionally, a fluorescence microscope was employed to measure the buildup of glutathione and hydrogen peroxide in the roots. The study reveals that nematodes adversely affect both radical scavenging capacity and structural components. Nevertheless, treatments involving vermicompost substantially enhance free radical scavenging capacity and mitigate the structural abnormalities induced by nematodes. All of these findings imply that vermicompost can reduce nematode damage and serve as an alternative to chemical nematicides. This is the first study in literature to focus on tomato plant structural and physiological markers, including Fourier transform infrared spectroscopy (FTIR), carbon hydrogen nitrogen (CHN), and free radical scavenging capacity during nematode stress after supplementing with vermicompost for 45 days in field conditions.