This study evaluated the physiological responses, hormonal signaling, osmotic and nutrient levels, as well as the performance of essential oils, antioxidant enzymes, and secondary metabolites in Lavender plants subjected to chromium and fluoride toxicity and biochar application. The findings indicated that the administration of raw and especially multiple-chemical engineered biochars decreased fluoride (about 16-40%) and chromium (39-60%) levels in Lavender leaves, whereas raised CEC and soil pH, nitrogen (10-37%), potassium (20-47%), phosphorus (10-60%), magnesium (30-49%), calcium (20-50%), zinc (39-240%), iron (40-120%), plant biomass, and photosynthetic pigments of Lavender plant leaves under toxic fluoride and chromium conditions. The treatments with multiple-chemical engineered biochars decreased the osmotic stress and osmolyte concentration (carbohydrates, soluble proteins, and proline) in the leaves of Lavender plants. Both raw and multiple-chemical engineered biochars significantly enhanced the water content of plant leaves, reaching up to 10% under toxic circumstances. Moreover, these treatments decreased the synthesis of stress hormones such as jasmonic acid (4-17%), salicylic acid (29-49%), and abscisic acid (30-66%), while increasing the production of Indole-3-acetic acid (IAA) (15-29%) in Lavender plants subjected to chromium and fluoride stress. The use of multiple-chemical engineered biochars showed notable efficacy in enhancing antioxidant enzyme's activity against oxidative damage induced by metal toxicity and decreasing proline accumulation. Maximum concentrations of linalyl acetate, borneol, camphor, and linalool were achieved under fluoride and chromium stress conditions by metaphosphoric acid-engineered biochar. Multiple-chemical engineered biochars application can be inferred as valuable approach to enhance both the quality and quantity of lavender essential oil under conditions of fluoride and chromium-induced stress.

Soil salinity is represent a significant environmental stressor that profoundly impairs crop productivity by disrupting plant physiological functions. To mitigate this issue, the combined application of biochar and nanoparticles has emerged as a promising strategy to enhance plant salt tolerance. However, the long-term residual effects of this approach on cereal crops remain unclear. In a controlled pot experiment, rice straw biochar (BC) was applied in an earlier experiment at a rate of 20 t/ha, in conjunction with ZnO and Fe2O3 nanoparticles at concentrations of 10 mg L- 1 and 20 mg L- 1. Two rice genotypes, Jing Liang You-534 (salt-sensitive) and Xiang Liang You-900 (salt-tolerant), were utilized under 0% NaCl (S1) and 0.6% NaCl (S2) conditions. Results showed that, application of residual ZnOBC-20 significantly enhanced rice biomass, photosynthetic assimilation, relative chlorophyll content, SPAD index, enzyme activities, K+/Na+ ratio, hydrogen peroxide (H2O2) levels, and overall plant growth. Specifically, ZnOBC-20 increased the tolerance index by 142.8% and 146.1%, reduced H2O2 levels by 27.11% and 35.8%, and decreased malondialdehyde (MDA) levels by 33% and 57.9% in V1 and V2, respectively, compared to their respective controls. Residual of ZnOBC-20 mitigated oxidative damage caused by salinity-induced over-accumulation of reactive oxygen species (ROS) by enhancing the activities of antioxidant enzymes (SOD, POD, CAT, and APX) and increasing total soluble protein (TSP) content. Xiang Liang You-900 exhibited a less severe response to salinity compared to Jing Liang You-534. Additionally, residual of ZnOBC20 significantly enhanced the anatomical architecture of both root and leaf tissues and regulated the expression levels of salt-related genes. Residual of ZnOBC-20 also improved salt tolerance in rice plants by reducing sodium (Na+) accumulation and enhancing potassium (K+) retention, thereby increasing the K+/Na+ ratio under saline conditions. The overall results of this experiment demonstrate that, residual effects of ZnOBC-20 not only improved the growth and physiological traits of rice plants under salt stress but also provided insights into the mechanisms behind the innovative combination of biochar and nanoparticles residual impacts for enhancing plant salt tolerance.

Conventional curing agents are associated with environmental impacts when treating Zn(2+)contaminated soils. To overcome this limitation. In this study, we study a new type of MgO-CSB curing agent. Namely, corn stover biochar is modified with activated MgO. Modification of corn stover biochar using activated MgO, and carbonation curing was adopted to solidify/stabilize the Zn(2+)contaminated soil. The curing efficacy of Zn(2+)contaminated soil under modified mass ratio, Zn2+ concentration, carbonation time, and curing agent incorporation was investigated. The findings indicate that the optimal adsorption efficiency was attained following the co-pyrolytic modification of activated MgO with corn stover biochar at 700 degrees C. The optimal modified mass ratios for curing were found to be 1:1, 1:2, and 2:1 at Zn2+ concentrations of 0.1 %, 0.5 %, and 1 %, respectively. At a lower Zn2+ concentration, peak carbonization intensity is achieved at 0.5 hours, while at a 1 % Zn2+ concentration, peak intensity is reached at 1 hour. The deformation modulus of the cured soil increases as the curing agent dosage increases and the soil aggregates become denser. SEM results show that: The carbonization and curing reaction products are mainly nesquehonite and Mg (OH)(2). The internal structural damage of the cured soil was aggravated by the increase in Zn(2+)concentration, and the generation of nesquehonite and Mg (OH)(2) was inhibited; The carbonation time was extended to 1 h and the soil structure stability was enhanced.