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In the present work, we analyzed the histochemical aspects of Passiflora edulis seeds reserve mobilization during the first ten days of germination. Our results showed that mainly lipids present in the endosperm are used as a reserve source, and their levels reduce at the same time the radicle protrudes, between the fourth and sixth day of sowing. Furthermore, protein bodies are present in the cotyledons, which are degraded as germination occurs and are almost depleted by the time of radicle protrusion. Starch grains also appear in the late germination period, and it is not clear if there is any reserve wall polysaccharide consumption in the endosperm.Keywords: seed germination, lipid bodies, protein globules, carbohydrates. Análise histoquímica da mobilização de reservas em sementes de Passiflora edulis Sims fo. flavicarpa O. Deg (maracujá amarelo) durante a germinação ResumoNo presente trabalho analisamos os aspectos histoquímicos da mobilização de reservas das sementes de Passiflora edulis, durante os primeiros dez dias de germinação. Nossos resultados mostraram que principalmente lipídios presentes no endosperma são utilizados como reserva, com o seu nível começando a diminuir ao mesmo tempo em que ocorre a protrusão da radícula, entre o quarto e sexto dia do início da embebição. Corpos proteicos também estão presentes nos cotilédones, e são degradados à medida que ocorre a germinação e são consumidos quase totalmente quando da protrusão da radícula. Grãos de amido também aparecem no período tardio de germinação, e não está claro se há ou não consumo de polissacarídeos de reserva de parede no endosperma.Palavras-chave: germinação de sementes, corpos lipídicos, glóbulos proteicos, carboidratos.

To further investigate the recently observed invasion of a new weed in the São Paulo areas, Brazil, we studied the germination performance and emergence characteristics of Bidens sulphurea. We measured the seed germination under different fixed temperatures (15, 20, 25, 30 and 35°C), photoperiods (18h/6h, 12h/12h, 6h/18h and 0h/24h [light/dark], respectively), light quality (white, blue, yellow, green, red and dark condition); and emergence in two seasons (winter and spring) in different sowing depths (0, 1, 3, 5, 7 and 9 cm). This species has the ability to germinate and emerge above 90% in a range of conditions of light, but it is very sensitive to variations in temperature, and several reductions on its germination and emergence are found bellow 20°C. The emergence of this species is severely controlled by seasonality and could occur up to 9 cm depth in Brazilian spring.

The Yellow Passion fruit is of great economic and cultural value in Brazil, the country with the largest production and consumption nowadays. Despite its great importance, the mobilization of the seed reserves is unknown. Therefore, our objective was to evaluate the histological and biochemical changes that occur in the seed during the first ten days of germination. Carbohydrates, lipid and protein extractions were done along with seed histochemical analysis at 0, 2, 4, 6, 8 and 10 days of germination under continuous white light and darkness. The results showed that lipids are the main reserve, for its consumption is high during germination, but there are also variations in protein and carbohydrates levels that may be involved in the germination process.

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<p>The increase in atmospheric CO<sub>2</sub> concentration positively affects plant carbon assimilation and carbon stock in different biomes. However, there are uncertainties regarding how plants in tropical forests, especially in the Amazon rainforest, will respond to this increase, since a large part of the soils in the region present natural low phosphorus (P) availability, which could constrain positive effects of elevated CO<sub>2</sub>. Here, we investigated if P addition would interfere on leaf primary carbon metabolism and aboveground development responses under elevated CO<sub>2</sub>. For that, we used 46  seedlings of <em>Inga edulis</em> Mart., a native leguminous nitrogen-fixing species, exposed for 10 months (November 2019 - September 2020) to CO<sub>2</sub> and P treatments. Plants grew in pots - half with natural P availability (-P) and half with P addition (+P) -, inside CO<sub>2</sub> enrichment chambers - half with ambient CO<sub>2</sub> (aCO<sub>2</sub>) and half with elevated CO<sub>2</sub> (aCO<sub>2 </sub>+ 200 ppm; eCO<sub>2</sub>), - in the understory of a primary forest in Central Amazonia, Manaus, Brazil.  A factorial experimental design was used, with 11-12 plants for each treatment: aCO<sub>2</sub>-P (control), aCO<sub>2</sub>+P, eCO<sub>2</sub>-P and eCO<sub>2</sub>+P. To assess the carbon metabolism, we measured light-saturated net CO<sub>2</sub> assimilation (A<sub>sat</sub>), leaf respiration in the light (R<sub>light</sub>), leaf respiration in the dark (R<sub>dark</sub>) and photorespiration (P<sub>R</sub>). To assess aboveground development, we measured plant height and diameter, crown height and diameter,  number of leaves and total leaf area. We found that eCO<sub>2, </sub>regardless of P availability, significantly increased A<sub>sat</sub> and R<sub>light</sub>, while decreasing R<sub>dark </sub>and A<sub>sat</sub>:R<sub>dark </sub>ratio, but it did not affect P<sub>R </sub><sub>.</sub> Those results suggest that seedlings indeed assimilated more carbon under eCO<sub>2</sub>. However, irrespective of CO<sub>2 </sub>treatment, +P significantly increased aboveground responses. Under P addition, plants showed greater height and greater crown development (higher crown height and diameter and larger leaves) compared to control or eCO<sub>2</sub>-only. Plant diameter and number of leaves did not respond to any treatment. We did not find differences between +P seedlings under different CO<sub>2</sub> treatments (aCO<sub>2</sub>+P and eCO<sub>2</sub>+P), indicating that only P had an effect on these responses. Still, there were substantial changes on some of the aboveground responses between these treatments, particularly in total leaf area which increased 60% (aCO<sub>2</sub>+P) and 126% (eCO<sub>2</sub>+P) compared to control. Overall, we observed a distinguished pattern, in which eCO<sub>2</sub> mainly affected physiological responses, while P addition consistently affected aboveground development. The lack of response of aboveground components under eCO<sub>2</sub> suggests that the extra carbon assimilated was not necessarily used to aboveground development as shown by many studies. Our findings indicate that, in the short-term, eCO<sub>2</sub> is highly important in determining changes in plant metabolism whereas it has little impact on growth, even when nutrient limitation is alleviate. However there is still need to understand if such responses will persist in the long-term and in other species, as these processes are key factors in determining forest responses to climate change.  </p>

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