Brazilian soils are predominantly rich in aluminum, which becomes mobile at pH < 5, affecting sensitive plants; however, some species have developed aluminum tolerance mechanisms. The purpose of this study was to compare the physiological responses of Crotalaria genus species, family Fabaceae, which have the ability to associate with nitrogen-fixing bacteria under the influence of Al³⁺ in the soil. The soil used was Oxisol; the experimental design was in randomized blocks in a factorial scheme (2 × 3): soil factor (available toxic aluminum content; correction of dolomitic limestone—MgCO₃) and species factor (C. juncea; C. spectabilis; C. ochroleuca); cultivated within 43, 53, and 53 days, respectively, with five replications; 30 experimental samples. Mass and length, pigments, gas exchange, and changes in nitrogen metabolism were evaluated. C. juncea showed a higher concentration of amino acids in the leaves, internal carbon, and stomatal conductance in soil with Al³⁺, as well as higher production of ureides, allantoinic acid, allantoic acid, proteins, and amino acids in the nodules, with 78% of the Al³⁺ accumulation occurring in the roots. C. ochroleuca demonstrated greater shoot length and nodule number production in limed soil; in soil with Al³⁺, it showed a 91% increase in chlorophyll a content and 93% in carotenoids. C. spectabilis showed a 93% increase in ureide production in the leaves in soil with Al³⁺.

Zinc (Zn) is an essential micronutrient in the plant life cycle, playing catalytic, structural, and regulatory roles in various physiological processes. However, when present in excess, Zn becomes a potentially toxic element (PTE), causing adverse effects ranging from impaired seed germination to inhibited plant growth and development. Understanding plant responses to increasing Zn concentrations in the soil is fundamental for the recovery of degraded areas and for assessing phytoremediation potential. This study aimed to evaluate the effects of different Zn concentrations on the emergence of Moringa oleifera Lam. seedlings, comparing the responses to two Zn sources in the soil: zinc chloride (ZnCl₂) and zinc sulfate (ZnSO₄). The experiment was conducted in a greenhouse under a completely randomized factorial design with four replicates. Treatments consisted of six Zn concentrations: 0 (control), 100, 200, 300, 400, and 500 mg Zn dm^-3 of soil, for both sources. After a 30-day stabilization period (days after element application, DAE), M. oleifera seeds were sown and maintained for 15 days, after which emergence and biometric parameters were evaluated. Data were subjected to analysis of variance, and when significant differences were detected, the Scott-Knott test at a 5% significance level was applied to compare treatments and sources. High Zn concentrations (400 and 500 mg Zn dm^-3 of soil) negatively affected seedling emergence, regardless of the Zn source. ZnSO₄ proved to be the more phytotoxic source, significantly reducing both the emergence percentage and speed, as well as biomass accumulation in the seedlings.

Micronutrients when present in high concentrations can become toxic to plants. Nickel exemplifies this phenomenon, having been considered essential for higher plants since the 1980s. Despite its beneficial effects on seed germination, growth and photosynthesis, an excess of Ni triggers the production of reactive oxygen species, thus exerting harmful effects on physiological and biochemical processes. The literature on this element exists mainly in narrative form, lacking scoping and systematic reviews and meta-analyses, which are crucial for understanding the progression of research in this field over the decades and for conceiving new directions of investigation. To begin to fill this gap, our scoping review, conducted using the PRISMA protocol, aims to outline the plant species under study, methodologies employed, and physiological markers used by peer-reviewed articles published from 2013 to 2022 focusing on the Fabaceae family, taking into account their diversity, economic, social importance and potential for use in phytoremediation programs. Our key findings indicate that Glycine max emerges as the most extensively studied species within the Fabaceae family. Research efforts predominantly target biotic stress, fertilization, and toxicity as primary objectives. However, categories covering physiological data such as nodules, biological nitrogen fixation, carbon metabolism, and gas exchange were underrepresented in the literature.

Copper (Cu) is a naturally occurring element in soils, and at adequate concentrations, it is essential for plant survival. However, excessive Cu can lead to contamination, impairing soil quality and affecting the development of living organisms. The present study aimed to evaluate the physiological responses of Stizolobium aterrimum plants grown in soils contaminated with increasing doses of copper. The experiment was conducted in a greenhouse under controlled temperature conditions. Five treatments were applied (0, 30, 60, 240, and 480 mg dm⁻³). After 51 days of cultivation, the plants were harvested, and their tissues were separated into leaves, roots, and nodules. Nitrogen compounds were extracted, and the contents of total soluble amino acids, ureides, and soluble proteins were quantified. The activity of the nitrogenase enzyme was analyzed in vivo. The results indicate that Stizolobium aterrimum is partially tolerant to copper contamination, exhibiting adequate growth and metabolism in the presence of moderate Cu concentrations. However, increasing Cu levels in the soil reduce fresh biomass production and lead to higher copper accumulation in the root system. High soil Cu concentrations also affect the absorption of other nutrients, in addition to copper itself. Cu doses around 240 mg dm³ can already be considered toxic.