Aline Redondo Martins

Nickel (Ni) is an essential micronutrient for plants, but its excess can disrupt physiological functions and impair growth. This study aimed to evaluate the morphophysiological responses of Calopogonium mucunoides and Canavalia ensiformis under increasing Ni concentrations (0, 120, 240, and 360 mg dm⁻³). Gas exchange, antioxidant enzyme activity, and leaf micromorphology were assessed using infrared gas analysis and scanning electron microscopy. C. mucunoides exhibited stable trichome and stomatal densities, increased chlorophyll concentration, and elevated peroxidase activity at 240 mg dm⁻³ Ni, but showed membrane instability and reduced water use efficiency. In contrast, C. ensiformis displayed higher morphological and physiological plasticity, evidenced by pronounced variation in stomatal conductance and superoxide dismutase activity (up to 54% RDPI), while maintaining photosynthetic rate and pigment stability across treatments. This enhanced plasticity under Ni stress suggests a greater acclimation capacity and highlights C. ensiformis as a promising candidate for phytoremediation of Ni-contaminated soils. These findings advance understanding of legume acclimation to nickel stress and provide valuable insights for sustainable agriculture in contaminated environments.

This study demonstrates that Moringa oleifera Lam. exhibits morphophysiological adjustments to excess zinc, maintaining photosynthesis and cell membrane in

Orchids exhibit remarkable diversity in terms of form, color, and fragrance, and are highly valued for their ornamental potential. In the Brazilian Cerrado, several native epiphytic species, including Cattleya cernua (Lindl.), are increasingly threatened by habitat loss and uncontrolled wild harvesting, leading to significant genetic erosion. In this context, conservation strategies and the development of optimized in vitro culture protocols are essential for preserving these species. This study optimized in vitro growth and established an acclimatization protocol for C. cernua by evaluating the effects of salt and sucrose concentrations, plant flour supplementation, and substrate types and fertilizer levels on acclimatization performance. Results indicated that the MS medium at 25% supplemented with 10 g L⁻¹ sucrose promoted the greatest shoot growth, number of leaves, and pseudobulb formation. The addition of cashew nut flour at 10 g L⁻¹ significantly enhanced both shoot and root development, increasing leaf and root numbers compared to other treatments. Data showed that coconut fiber, even without fertilization, supported high survival rates and robust plant growth. Collectively, these findings demonstrate that the in vitro growth of Cattleya cernua is most effectively achieved using MS medium at 25% strength supplemented with 10 g L⁻¹ sucrose and 10 g L⁻¹ cashew flour, followed by acclimatization in coconut fiber without additional fertilization. This protocol represents an efficient, sustainable strategy for propagating and conserving this native Cerrado orchid species.

Savannas are fire-prone seasonal ecosystems determined by environmental filters such as fire, herbivory and water availability, which change the dynamics in these environments. Plants growing in such conditions have adaptive traits that enable them to survive under different disturbances and stresses, not only on the underground organs, but also on aerial organs. Therefore, this work aimed to describe morphoanatomical and structural traits of the stem and leaves of eight representative legume species from Cerrado, related to ecological functions associated with resistance against environmental filters present in savanna ecosystems. We performed morphoanatomical and structural analysis of aboveground organs using four techniques: (1) Samples included in historesin were sectioned on a rotary microtome; (2) Fresh samples were sectioned on a sliding microtome; (3) Fresh samples were free-hand sectioned (4) The ultrastructural analysis of the leaf samples was performed on Scanning Electron Microscope. According to morphoanatomical analyses, it was possible to identify two functional groups, such as plants with xeromorphic traits and plants with mesomorphic traits. The traits protect plants from flame temperatures, sun exposure, drought, herbivory, and other environmental filters. Resprouting species of this study also have several important morphological and anatomical traits that enable these species to resist drought, fire, herbivory and other filters. The integration of morphoanatomy to functional ecology may be a remarkable tool in understanding vegetation responses to disturbances and stresses.

Background: Irrigation has been a strategy used to reduce losses due to drought, which combined with a good supply of nitrogen (N), can improve the protective system of cotton plants. The objective of this study was to investigate the effects of irrigated and rainfed cotton cultivation using different rates and sources of N. Cotton cultivation was carried out in Selvíria-MS field in the 2017/2018 harvest. The experiment was conducted in randomized blocks, which were designed in a 4 × 2 × 2 factorial scheme. The factors were composed of 0, 40, 80, and 150 kg·hm ⁻² level of N, using two sources of N under rainfed and irrigated systems. Results: The provision of irrigation provided an increase in the levels of chlorophylls (Chl) a, Chl b, total Chl, carotenoids, pheophytin, leaf chlorophyll index (LCI), N content, nitrate (NO ₃ ⁻ ), sucrose (SUC), the number of vegetative and reproductive branches, boll mass, and seed cotton productivity. There was no effect of N sources on any of the characteristics evaluated. Application of 150 kg·hm ⁻² level of N increased in 11%, 59%, 22%, 15%, 15% and 17% in LCI, NO ₃ ⁻ , N, total amino acids (TA), SUC, and proline concentration in leaves, compared with 0 kg·hm ⁻² of N, respectively. Application of 150 kg·hm ⁻² level of N improved the leaf catalase activity (CAT) under the irrigation system; however, in a rainfed system, the highest CAT was observed at rates of 0 and 150 kg·hm ⁻² level of N. Irrigation increased in 55%, 117%, 68%, 46%, 8%, 36%, 24%, 118%, 48%, 10%, 11% and 72% in Chl a, Chl b, total Chl, CAR, LCI, pheophytins (Pheo), SUC, NO ₃ ⁻ , the number of vegetative branches, the number of reproductive branches, mass of 20 bolls and seed cotton yield compared with rainfed system, respectively, however, the antioxidant system and the ammonium content of plants was stimulated by rainfed cultivation. Conclusions: Antioxidant responses increased during droughts in cotton farming, which may be connected to oxidative stress-related losses. Better N metabolism, photosynthetic pigments, and manufacturing components were all made possible by irrigated cultivation. The delivery of 150 kg·hm ⁻² of N in topdressing in cotton agriculture promoted the N metabolism, sucrose, total amino acids, and the plant’s defense mechanism against oxidative stress.

Fire is a natural disturbance in the Brazilian Cerrado that modulates the vegetation structure. Protium heptaphyllum, a woody species of the family Burseraceae, is common in this biome. The resin produced in secretory canals immersed in the phloem of the stem and leaves of this species plays important ecological and industrial roles. The aim of this study was to investigate the influence of fire on the development of resin canals in the leaves and stem of P. heptaphyllum and on the chemical profile of substances produced in the leaves. Young plants were subjected to controlled fire experiments. Leaf and stem portions were analyzed using light microscopy; the chemical compounds in the leaves were identified through gas chromatography–mass spectrometry. The percentage area occupied by secretory canals in the leaf midrib was higher in fire-treated plants than in control plants. Similarly, the density of secretory canals and their lumen area were higher in young stems (primary growth) of fire-treated plants. By contrast, although the canal density in the secondary phloem was lower in older stem portions (secondary growth) in fire-treated plants, their lumens were larger, resulting in similar data regarding the total lumen area of the secretory canals in fire-treated and control plants. The main chemical compounds identified in the leaves were vitamin E, sitosterol, α-amyrin, squalene, and β-amyrin. Three compounds showed significant increases in fire-treated plants, with vitamin E being the only one reduced by fire. Our findings reveal the plasticity of the secretory system and of the biochemical properties of the leaves of P. heptaphyllum in response to fire. These results are important when considering the current increase in fires caused by climate change and human activity in different ecosystems around the world.