Adamir da Rocha Nina Junior

Phosphorus (P) availability is a critical constraint for plant growth in tropical ecosystems, primarily due to its low mobility and high fixation by soil colloids. The use of phosphate-solubilizing microorganisms (PSMs) is a sustainable strategy to enhance phosphorus bioavailability, particularly in highly weathered and nutrient-depleted soils. These microorganisms, including bacteria, fungi, actinobacteria (Phylum Actinomycetota), and cyanobacteria, convert insoluble phosphorus into plant-available forms through biochemical pathways such as organic acid production, enzyme secretion, and siderophore release. Although widely studied in agricultural systems, the role of PSMs in forest ecosystems, especially in the Amazon, remains poorly explored. This review synthesizes current knowledge on the diversity, solubilization mechanisms, and applications of PSMs, emphasizing their potential to improve seedling establishment and promote ecosystem resilience in forest restoration efforts. The integration of microbial biofertilization into silvicultural and agroforestry practices may reduce dependence on chemical fertilizers, mitigate environmental impacts, and restore soil fertility in degraded Amazonian landscapes. We underscore the urgent need for further research on locally adapted PSM strains and their functional interactions with native tree species. Ultimately, PSMs represent a promising biotechnological tool for restoring the structure and function of tropical forest ecosystems.

The allocation and distribution of primary resources in planting systems can significantly influence the physiological and growth performance of Bertholletia excelsa , an Amazonian tree of significant socioeconomic and ecological importance. This study was carried out for two years to investigate the resource availability and ecophysiological responses of B. excelsa cultivated in different planting systems in 3 × 3 spacing: (1) pure plantation, (2) mixed plantation using B. excelsa and Inga edulis and (3) an agroforestry system (AFS); the AFS with intercropping of Theobroma cacao and Musa sp. between B. excelsa and I. edulis trees, respectively. Planting systems (Pure, Mixed and AFS) were evaluated based on site resource availability, growth rate, gas exchange, nutrient use efficiency, and nutritional status of B. excelsa . This study showed greater availability of light in pure plantations and a better soil quality index in the AFS. The Brazilian nut trees in the AFS showed higher values of photosynthesis ( P _N ), stomatal conductance ( gs ), transpiration ( E ), foliar content of phosphorus, calcium, and magnesium, and greater efficiency in the use of nitrogen and potassium. Brazilian nut tree saplings showed greater investment in light capture, with greater height growth, and no difference in diameter growth rates. From the present study, it can be concluded that in the initial growth phase relating to the first installation years of field plantings, the AFS favors the ecophysiological performance and height growth of B. excelsa saplings in degraded areas of Eastern Brazilian’s Amazon.

To investigate how and to what extent there are differences in the photosynthetic plasticity of trees in response to different light environments, six species from three successional groups (late successional, mid‐successional, and pioneers) were exposed to three different light environments [deep shade – DS (5% full sunlight – FS), moderate shade – MS (35% FS) and full sunlight – FS]. Maximum net photosynthesis (A_max), leaf N partitioning, stomatal, mesophile, and biochemical limitations (SL, ML, and BL, respectively), carboxylation velocity (V_cmax), and electron transport (J_max) rates, and the state of photosynthetic induction (IS) were evaluated. Higher values of A_max, V_cmax, and J_max in FS were observed for pioneer species, which invested the largest amount of leaf N in Rubisco. The lower IS for pioneer species reveals its reduced ability to take advantage of sunflecks. In general, the main photosynthetic limitations are diffusive, with SL and ML having equal importance under FS, and ML decreasing along with irradiance. The leaf traits, which are more determinant of the photosynthetic process, respond independently in relation to the successional group, especially with low light availability. An effective partitioning of leaf N between photosynthetic and structural components played a crucial role in the acclimation process and determined the increase or decrease of photosynthesis in response to the light conditions.

We investigate and characterize the morphophysiological changes related to germination and the initial growth and development of seedlings of wild and cultivated genotypes of the genus Hevea spp. in finding to add value to new clones. Seeds from six genotypes (H. brasiliensis (Willd. Ex A. Juss) Müll. Arg, H. guianensis Aubl., H. spruceana (Benth.) Müll. Arg., RRIM 600, Fx 3844, and IAN 873) were sterilized, and their imbibition curve, germination parameters, and initial seedling growth were characterized. In parallel, the morphology of the germination and post-germination stages was monitored from seeds germinated in washed sand. Morphological differences in the seeds/embryos, different strategies in the imbibition process, emergence, and initial seedling growth were observed. The species H. guianensis and H. spruceana showed the greatest differences in size, shape, and color of the seeds/embryos and initial seedling growth. The characteristics of the seed coat patterns, the seedling imbibition, growth, and development processes can serve as morphophysiological markers for genotype identification and selection. This is the first morphophysiological study of seeds and seedlings of wild and cultivated genotypes of species of the genus Hevea. We conclude that there is considerable phenotypic variability among species of the Hevea genus regarding seed and seedling morphophysiology, which can be explored in the rubber tree breeding programs.

Guarana (Paullinia cupana Kunth var. sorbilis) is a typically Amazonian plant of high economic value due to the compounds found in its seed. For guarana to reach the maximum productive potential, management practices such as weed control are necessary. The use of herbicides is a viable alternative, however, its drift may lead to adverse effects on the primary and secondary plant metabolisms and cause losses in crop production. This study evaluated the differential drift effects of glyphosate doses on the physiology of guarana plants and the production of compounds of economic interest in their seeds. Glyphosate doses (57.6, 115.2, 230.4, 460.8 g ae ha⁻¹) were applied to adult guarana plants after the flowering period. The photosynthetic functions and metabolism effects were evaluated. Herbicide treatments led to oxidative stress due to increased lipid peroxidation and increased carbohydrate and amino acid in their leaflets. Despite this, glyphosate showed no effect on fruit production or the content of secondary metabolites of commercial interest in seeds.