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Current climate change scenarios require strategies that mitigate the effects of water deficits. Given that chitosan stimulates induced resistance responses, we tested the hypothesis that foliar application of this polysaccharide can have positive effects on the primary metabolite, antioxidant, and osmoregulatory metabolisms of sorghum, mitigating the effects of water deficit on grain yield. Sorghum plants were cultivated under either irrigated or water-deficit conditions and were either treated or untreated with chitosan, and we assessed the following responses: water potential, gas exchange, nutritional status, biosynthesis of primary and osmoregulatory metabolites, the activity of the antioxidant system constituents, and hydrogen peroxide and malondialdehyde contents. An active methodology was used to impose water stress on plants grown in pots with 20 kg of soil, 06 replications per treatment. Sorghum plants subjected to water deficit that were treated with chitosan exhibited higher stomatal conductance and transpiration than the untreated plants. Water restriction reduced the nutrient contents of leaves, but in the irrigated plants, chitosan treatment increased the tissue contents of certain nutrients and leaf concentrations of total proteins and total amino acids. In the plants under water-deficit conditions that were treated with chitosan, an elevated photosynthetic rate contributed to an increase in carbohydrate accumulation and a higher production of panicle and grain dry biomass compared with the untreated plants. The activity of catalase and ascorbate peroxidase also increased in response to chitosan. Overall, chitosan was effective in enhancing the water deficit tolerance of sorghum plants cultivated under water-deficit conditions by 57%. With this work, we generate perspectives for studies focusing on the development of water-deficit-resistant sorghum lineages, by means of chitosan elicitation.

Plants receiving insufficient concentrations of the different essential nutrients may respond symptomatically to this stress. However, when the first visible symptoms of nutritional deficiency appear, plants already exhibit significant changes in their structure. As seedlings of E. dysenterica are important for the recovery of degraded areas and as the fruits of this species are widely exploited commercially, we decided to evaluate whether the omission of nutrients may affect the leaf anatomical ultrastructure, dry matter production and the synthesis of photosynthetic pigments in this plant, in an attempt to use data of this nature to predict symptoms of nutritional deficiency in seedlings of this species. For this purpose, we grow seedlings in a hydroponic system, offering all nutrients and also omitting each nutrient individually. Thus, we evaluated the effect of the omission of each nutrient on the anatomical leaf structure, dry mass production and the synthesis of photosynthetic pigments. Seedlings that grew in the absence of Ca and Mn exhibited compromised spongy parenchyma and mesophyll development, while the omission of K and Mg increased the number of epidermal cells and stomata. Low dry mass production in E. dysenterica was related to the omission of S and Mn, while P, N and Fe deficiencies directly affected the synthesis of pigments. Thus, leaf anatomical and physiological data can predict nutritional deficiency conditions, enabling the user to diagnose the deficiency before the onset of symptoms in E. dysenterica seedlings. Our results may help investigators to understand the effects of nutritional omissions on other native Cerrado plants

The sustainable development of agriculture can be stimulated by the great market availability of bio-inputs, including phosphate-solubilizing microbial strains. However, these strains are currently selected using imprecise and questionable solubilization methodologies in solid or liquid media. We hypothesized that the hydroponic system could be a more efficient methodology for selecting phosphate-solubilizing strains as plant growth promoters. This methodology was tested using the plant Glycine max as a model. The growth-promoting potential of the strains was compared with that of the Biomaphos® commercial microbial mixture. The obtained calcium phosphate (CaHPO4) solubilization results using the hydroponic system were inconsistent with those observed in solid and liquid media. However, the tests in liquid medium demonstrated poor performances of Codinaeopsis sp. (328EF) and Hamigera insecticola (33EF) in reducing pH and solubilizing CaHPO4, which corroborates with the effects of biotic stress observed in G. max plants inoculated with these strains. Nevertheless, the hydroponic system allowed the characterization of Paenibacillus alvei (PA12), which is also efficient in solubilization in a liquid medium. The bacterium Lysinibacillus fusiformis (PA26) was the most effective in CaHPO4 solubilization owing to the higher phosphorus (P) absorption, growth promotion, and physiological performance observed in plants inoculated with this bacterium. The hydroponic method proved to be superior in selecting solubilizing strains, allowing the assessment of multiple patterns, such as nutritional level, growth, photosynthetic performance, and anatomical variation in plants, and even the detection of biotic stress responses to inoculation, obtaining strains with higher growth promotion potential than Biomaphos®. This study proposed a new approach to confirm the solubilizing activity of microorganisms previously selected in vitro and potentially intended for the bio-input market that are useful in P availability for important crops, such as soybeans.

The sustainable development of agriculture can be stimulated by the great market availability of bio-inputs, including phosphate-solubilizing microbial strains. However, these strains are currently selected using imprecise and questionable solubilization methodologies in solid or liquid media. We hypothesized that the hydroponic system could be a more efficient methodology for selecting phosphate-solubilizing strains as plant growth promoters. This methodology was tested using the plant Glycine max as a model. The growth-promoting potential of the strains was compared with that of the Biomaphos® commercial microbial mixture. The obtained calcium phosphate (CaHPO4) solubilization results using the hydroponic system were inconsistent with those observed in solid and liquid media. However, the tests in liquid medium demonstrated poor performances of Codinaeopsis sp. (328EF) and Hamigera insecticola (33EF) in reducing pH and solubilizing CaHPO4, which corroborates with the effects of biotic stress observed in G. max plants inoculated with these strains. Nevertheless, the hydroponic system allowed the characterization of Paenibacillus alvei (PA12), which is also efficient in solubilization in a liquid medium. The bacterium Lysinibacillus fusiformis (PA26) was the most effective in CaHPO4 solubilization owing to the higher phosphorus (P) absorption, growth promotion, and physiological performance observed in plants inoculated with this bacterium. The hydroponic method proved to be superior in selecting solubilizing strains, allowing the assessment of multiple patterns, such as nutritional level, growth, photosynthetic performance, and anatomical variation in plants, and even the detection of biotic stress responses to inoculation, obtaining strains with higher growth promotion potential than Biomaphos®. This study proposed a new approach to confirm the solubilizing activity of microorganisms previously selected in vitro and potentially intended for the bio-input market that are useful in P availability for important crops, such as soybeans.

Sclerotinia sclerotiorum is a necrotrophic parasitic fungus that causes Sclerotinia stem rot (SSR), which is currently one of the most difficult agronomic crop diseases to control. A number of plants of the Brazilian Cerrado biome have been shown to be important sources of symbiotic microorganisms with biotechnological potential, so we decided to test the potential of bacteria isolated from the dwarf jelly palm, Butia archeri (Arecaceae) for the control of the pathogenic effects provoked by S. sclerotiorum. For this, we bioprimed seeds and evaluated the effects of this biopriming on the OJIP transient patterns prior to and following infection by the phytopathogen. Plants treated with the BA48R strain of Enterobacter sp., and in particular, those treated with the BA88R strain of Bacillus cereus presented the best results in terms of the loss/gain of the physiological and symptomatological variables evaluated. The plants bioprimed with BA88R presented high post-infection levels of total chlorophyll (33.35 FCIs) and chlorophyll a (26.39 FCIs), maintained a high Nitrogen Balance Index (NBI = 18.87), and synthesized low concentrations of flavonoids (1.39). These plants also maintained high levels of PIABS (1.111) and PITOTAL (1.300) following infection, and low levels of Di0/RC (0.602), which indicates that, in the presence S. sclerotiorum, the efficiency of the photosynthesis in the plants treated with these bacteria was less affected in the reaction centers, as confirmed by the negative amplitude recorded in the L band. The present study reconfirms the importance of the use of chlorophyll fluorescence for the diagnosis of disease and conditions of stress in crop plants, in addition to demonstrating the effectivenesss of the BA48R bacterial strain and, in particular, the BA88R strain on systemic resistance induction and suppression of S. sclerotiorum in Glycine max plants, with enormous potential for the development of more sustainable agricultural processes.

Rhizospheric and endophytic microorganisms compete with phytopathogens for ecological niches, which led us to hypothesise that bacteria symbiotic with the palm Butia archeri may influence the germination of the seeds of Glycine max and provide effective biocontrol against phytopathogens. We evaluated seed biopriming with rhizospheric strains of the bacteria Enterobacter asburiae and Bacillus cereus, and endophytic strains of Enterobacter cloacae, Enterobacter sp., Bacillus sp. and Pantoea agglomerans. Seeds treated with E. cloacae and Enterobacter sp. presented higher germination potential, germination velocity index and accumulation of fresh biomass in the radicle than seeds that were untreated or treated with other bacteria. Seeds that were not treated were also most affected by fungi, in particular Fusarium and Penicillium, during storage. When treated with B. cereus and E. asburiae, fungal infestation of the stored seeds was reduced to levels similar to those found in seeds treated with chemical fungicide. Our combined analysis of the influence of these strains on radicular growth and the control of phytopathogens, indicates that the rhizospheric strains of B. cereus and E. asburiae may have the best potential for biocontrol. The present study also demonstrated that the microbiota associated with plants native to the Brazilian Cerrado may be a promising source of species or biomolecules with potential for the biocontrol of plant pathogens.

Cagaita (Eugenia dysenterica DC.) is a native fruit tree with high economical potential from the Brazilian Cerrado. However, little is known about the essential nutritional demands of its seedlings. To determine the nutrient demands of Cagaita, a greenhouse experiment was performed, in which plants were grown under hydroponic condition to assess the growth (length and diameter of stems, number of leaves, number of nodes, volume and length of roots, area of the leaf and crown and total dry weight of the leaves, stems and roots) and nutrient concentration (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn) at different time points after the plant were transferred into a nutrient solution. The seedling growth presented linear behavior until 180 days after transplantation. The total plant dry weight was 6.54 g after 180 days of transfer into the nutrient solution. The N content was positively correlated with the total dry weight and leaf area, whereas B was negatively correlated with the length of the stem and number of leaves. Macro and micronutrient concentrations presented the following order: N >Ca >K >P >Mg >S, Fe >Mn >B >Zn >Cu. A principal component analysis of the different sampling times provided important information used to define the growth variables.

Hydroponics is an excellent alternative approach for the production of seedlings, given the growing demand for fruiting trees for the reforestation or recuperation of degraded natural landscapes. In most cases, however, little is known about the optimal period for the maintenance of the seedling in the hydroponic system. Given this, we decided to investigate the hypothesis that morpho-anatomical and physiological alterations can be used to predict the optimal timing for the transplantation of the seedlings to the soil substrate, thereby guaranteeing the most cost-effective application of the hydroponic system. We selected Hymenaea courbaril L., an important Neotropical fruit tree, as the model for this study. We cultivated H. courbaril seedlings in a static hydroponic system and evaluated morpho-anatomical, physiological, and growth parameters over the course of seedling development (30, 60, 90, 120, 150, and 180 days after transplantation, DAT). We observed an interesting relationship between the increase in the density (SD) and conductance (gsw) of the stomata up to 120 DAT, which reflected higher rates of photosynthesis (A), but also a reduced efficiency in the use of water. In the subsequent intervals, the SD of the plants and the diameter of the radicular xylemic vessels elements (RVE) decreased, in an attempt to increase the efficiency of the use of this resource. We also observed an increase in the thickness of the palisade parenchyma (PP) prior to 120 DAT, which did not reflect a general increase in the thickness of the mesophyll, indicating an adjustment in the thickness of the spongiform parenchyma (SP). We also observed a progressive increase in photosynthetic efficiency up to 120 DAT, based on parameters such as the absorption flux energy per active reaction center (ABS/RC) and the photosynthetic performance index (PIABS), but after this period these indices decreased progressively. However, as the PIABS is an indicator of the plant&rsquo, s tolerance, its decline was associated with an increase in the dissipation of energy (DI0/RC), which indicates that, after 120 DAT, the plant pots may become a stress factor that limit the growth of H. courbaril seedlings. The results of the present study indicate conclusively that a 120-day period is the optimum for the maintenance of the H. courbaril seedlings in the hydroponic system, and also confirm the hypothesis that the morpho-anatomical and physiological responses observed in the plants can be used to predict the ideal period for the transplantation of the seedlings, contributing to a reduction in production time of the hydroponic system.

Knowledge of the mineral nutrition requirements of mangabeira (Hancornia speciosa Gomes) is relatively scarce and rudimentary because there is a lack of consistent data concerning its nutritional demands at different developmental stages. The aim of this research was to characterize the visual symptoms of macronutrient deficiencies and to evaluate the effects of these deficiencies on the growth, the production of dry matter, and the leaf content of mangabeira. To achieve this goal, a greenhouse experiment was conducted at the Goiano Federal Institute (Instituto Federal Goiano) in Rio Verde - GO, from January to June 2011 in which mangabeira plants were arranged in a random block design and grown in nutrient solutions. This experiment was replicated four times. The plants were treated with either a complete nutrient solution or a nutrient solution from which the individual macronutrient of interest (nitrogen (N), phosphorous (P), potassium (K), magnesium (Mg), calcium (Ca), or sulfur (S) had been omitted. The omission of a macronutrient from the nutrient solution resulted in morphological alterations that were characteristic symptoms of the particular nutritional deficiency and caused decreases in growth and dry matter mass production. The accumulation of macronutrients displayed the following order in mangabeira leaves: N>K>Ca>P>S>Mg. Os conhecimentos de nutrição mineral da mangabeira (Hancornia speciosa Gomes) são relativamente escassos e incipientes, faltando dados consistentes sobre sua demanda nutricional desde a fase de viveiro até a fase de produção. Com o objetivo de caracterizar os sintomas visuais de carências de macronutrientes, avaliar os efeitos da deficiência no crescimento, produção de massa da matéria seca e conteúdo foliar de mangabeira, foi conduzido um experimento em casa de vegetação no IF Goiano em Rio Verde - GO, nos períodos de janeiro a junho de 2011, onde plantas de mangaba foram cultivadas em solução nutritiva, no delineamento de blocos casualizados, com quatro repetições. Os tratamentos foram constituídos de solução nutritiva completa e omissão individual de nitrogênio (N), fósforo (P), potássio (K), magnésio (Mg), cálcio (Ca) e enxofre (S). A omissão dos nutrientes na solução nutritiva resultou em alterações morfológicas, traduzidas como sintomas característicos de deficiência nutricional, diminuição no crescimento e produção de massa da matéria seca, e o acúmulo de nutrientes apresentou a seguinte ordem decrescente para os macronutrientes: N>K>Ca>P>S>Mg em folhas de mangabeira.

Nitrogen is an essential nutrient that plants generally require in large amounts. Knowing the nitrogen dose that stimulates primary and secondary metabolic pathways is important for the management of nitrogen fertilisation in plants in general; however, this information is still unavailable for seedlings of the cerrado cashew tree. Based on the hypothesis that the availability of nitrogen for Anacardium othonianum Rizz. seedlings can affect can affect the development of anatomical structures, as well as the synthesis of secondary metabolism compounds in leaves, an experiment was conducted to determine the qualitative and quantitative anatomy this tissue collected from plants of this species subjected to N doses of 0, 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 mmol L−1 in nutrient solution and evaluated the effect at 30 and 90 days after transplanting (DAT). The largest leaf morphoanatomical changes were observed under the doses of 0 and 15.0 mmol L−1 of N. The lowest stomatal density being observed in the plants exposed to an N dose of 15 mmol L−1. The level of flavonoids was not influenced by the availability of N in the solution; however, the absence of nitrogen directly affected the accumulation of phenolic compounds, alkaloids and polysaccharides present in the leaves, whereas the doses of 7.5, 10.0 and 12.5 mmol L−1 were essential to stimulate the presence of this latter compound in cerrado-cashew-tree seedlings maintained in nutrient solution. Regarding the epochs of evaluation, effect was observed only for the thickness of the adaxial epidermis. These data confirm the hypothesis that the leaf anatomy as well as the accumulation of secondary metabolism compounds in leaves of A. ohonianum can be modified because of the availability of N to the plant.

Hancornia speciosa Gomes (Mangaba tree) is a fruit tree belonging to the Apocynaceae family and is native to Brazil. The production of seedlings of this species is limited by a lack of technical and nutritional expertise. To address this deficiency, this study aimed to characterize the visual symptoms of micronutrient deficiency and to assess growth and leaf nutrient accumulation in H. speciosa seedlings supplied with nutrient solutions that lack individual micronutrients. H. speciosa plants were grown in nutrient solution in a greenhouse according to a randomized block design, with four replicates. The treatments consisted of a group receiving complete nutrient solution and groups treated with a nutrient solution lacking one of the following micronutrients: boron (B), copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), and molybdenum (Mo). The visual symptoms of nutrient deficiency were generally easy to characterize. Dry matter production was affected by the omission of micronutrients, and the treatment lacking Fe most limited the stem length, stem diameter, root length, and number of leaves in H. speciosa seedlings as well as the dry weight of leaves, the total dry weight, and the relative growth in H. speciosa plants. The micronutrient contents of H. speciosa leaves from plants receiving the complete nutrient solution treatment were, in decreasing order, Fe>Mn>Cu>Zn>B. A mangabeira (Hancornia speciosa Gomes) é uma frutífera pertencente à família Apocynaceae, originária do Brasil. A produção de mudas desta espécie em grande escala ainda é limitada pela escassez de conhecimentos técnicos e nutricionais. Para obter maiores esclarecimentos sobre o assunto, este trabalho objetivou caracterizar os sintomas visuais de deficiência de micronutrientes, avaliar o crescimento e o acúmulo de nutrientes foliar de mudas de mangabeira, submetidas a diferentes soluções nutritivas com suspensão de micronutrientes. Plantas de mangabeira foram cultivadas em solução nutritiva, dentro de casa de vegetação, no delineamento de blocos casualizados, com quatro repetições. Os tratamentos foram constituídos de solução nutritiva completa e omissão individual de boro, cobre, ferro, manganês, zinco e molibdênio. Os sintomas visuais de deficiências de nutrientes mostraram-se, de maneira geral, facilmente caracterizáveis. A produção de matéria seca foi afetada pela omissão de micronutrientes, e o tratamento que mais limitou o comprimento do caule, diâmetro do caule, comprimento da raiz, número de folhas de mudas de mangaba e massa seca das folhas, massa seca total e o crescimento relativo da mangabeira, foi a omissão de ferro. Os conteúdos de micronutrientes das plantas do tratamento completo obedeceram à seguinte ordem decrescente de micronutrientes Fe>Mn>Cu>Zn>B em folhas de mangabeira.