Andiroba (Carapa guianensis Aubl.-Meliaceae) is considered an Amazonian forest species with great potential for multiple use in natural forests. Because it is a native species of the Amazon rainforest, it has great socioeconomic importance for the extractive population due to the oil extracted from its seeds. The speed of emergence is an important factor in the establishment of seedlings, since the longer the seeds remain inside the soil, the seeds are in the soil, the greater the chances that the seeds will be attacked by fungi and soil insects. The objective of this work was to determinate the speed of andiroba emergence (Carapa guianensis Aubl.) seedlings and the development. The experiment was carried out in a greenhouse belonging to Federal Rural University of Amazonia (UFRA)-Capitão Poço, Brazil. Fruits of C. guianensis were collected in floodplain areas in northeastern of Pará. The treatments were arranged according to the seed mass. Were calculated 5 variables after sowing (emergence speed index; height; interference of the mass of andiroba seeds at the height of the seedlings stem; interference of the mass of andiroba seeds in the number of leaves; interference of the mass of andiroba seeds in the number of leaflets). The experimental design was completely randomized, consisting of 4 treatments with 5 replicates with 5 seeds per replicate (5 seeds per vessel), totaling 25 seeds per treatment. The data were statistically analyzed using the Tukey test at 5% probability with the software Assistat 7.6. The seed mass classes did not influence ESI (Emergence Speed Index). The seed mass promoted significant effects on 4 variables. The mass of the seeds of andiroba does not influence the ESI of seedlings for it own production. The heavy and very heavy seeds generated more developed plants.

The Byrsonima genus covers various fruit species known in the Brazilian Amazon as murucizeiro, which is considered as a species with good nutritional quality and features in its composition a variety of volatile compounds. The adaptation of plants to water stress is a complex physiological and biochemical phenomenon. Depending on the intensity and duration of stress, changes ranges from a rapid change in the flow of ions to improve the osmotic pressure, reduction of gas exchange, stabilization of cell structures by osmotic protection to a more drastic change in plant growth pattern. The aim of this work was to study gas exchange and carbon metabolism in young plants of muruci (Byrsonima crassifólia L.) submitted for water suspension. The experimental design was completely randomized with two water conditions: control and drought, with 14 repetitions, totaling 28 experimental units. The parameters analyzed were relative water content, transpiration, stomatal conductance, photosynthetic pigments, concentrations of starch, total soluble carbohydrates and sucrose. The suspension of irrigation for 25 days provided significant differences in all parameters, promoting decreases in the metabolic pathways of plants and reducing the relative water content by 26.92%, transpiration 90%, stomatal conductance 94.79%, photosynthetic pigments (Clrofila (42.1%), Chlorophyll b (50%), Carotenoids (45.1%) and overall (33.3%)) and starch in leaves and roots (73.43 and 63.63%), but increase in the control plants with the total soluble carbohydrates at 63, 87 and 39.5% and sucrose content as 64.73 and 43.99% in the leaves and roots. Therefore, these changes indicated that these plants are susceptible to soils with low water availability.

The aim of this work was to evaluate, by the physiological and growth variables, the behavior of paricá seedlings submitted to cadmium aplications. Cadmium is a importante metal due the industrial use, the accumulation in the environment, the high mobility in the soil-plant system, and possibly by changing physiological and growth parameters in plants. Among the plants that can be affected by this metal is the species (Schizolobium amazonicum Huber ex Ducke), known as paricá. Native from the amazona region, presents great social, economic and environmental potential. Among the physiological variables analyzed, cadmium interfered with photosynthesis, stomatal conductance and transpiration, mainly with the increase of the concentrations of this element. Among the correlated variables, the variable intrinsic efficiency of water use (EiUA), presented high in the stress conditions maintaining the minimum of water balance. For the growth variables, the cadmium provided a decrease in the height, diameter, number of leaves and leaflets influencing the low synthesis of photoassimilates. The phytotoxic element was mainly concentrated in the roots, but there was translocation to shoot, signaling a phytoextractive characteristic.

This study aimed to evaluate the effects of application of nitrogen sources and doses in the biochemical response of seedlings of Tachigali vulgaris L. G. Silva & H. C. Lima. The seedlings were grown in pots containing 3 dm 3 of soil. Nitrogen sources such as urea [(NH₂)₂CO], ammonium nitrate (NH 4 NO 3 ), ammonium sulfate [(NH 4 ) 2 SO 4 ] and calcium nitrate [Ca (NO 3 ) 2 ] were tested in five doses of 0, 75, 150, 225 and 300 mg dm -³. They were applied as a solution in four portions, 25, 50, 75 and 100 days after transplanting. The experimental unit consisted of a vase and a randomized block design (RBD) in factorial scheme (4 × 5), corresponding to 4 sources and 5 doses, with four replications, totally 80 vessels. The biochemical analyzes were performed at the end of the experiment and nitrate levels, nitrate reductase enzyme activity, free ammonium, total soluble amino acids, total soluble proteins, carbohydrates, sucrose and chlorophylls were determined. There was a reduction in the concentration of protein in leaf and root, with the application of ammonium nitrate and calcium nitrate. The conversion of nitrate into the root in amino acids shown to be dependent to the oxidation of carbohydrates, causing the reduction of the concentration of this solute increases with the supply NO 3 -. The results showed that for production of Tachigali vulgaris seedlings the dose of 150 mg dm -3 of N, applied in a piecemeal manner, at 25, 50, 75 and 100 days of transplanting with the ammonium nitrate fertilizer can be recommended.

Water stress limits the initial growth and development of maize mass and grain, as well as the physiological process for absorbing the amount of mineral elements. The objective was to evaluate the effect of silicon on germination and growth of corn seedlings submitted to water deficit. The experiment was carried out in the laboratory and the experimental design was completely randomized (factorial 3 × 4), with three concentrations of calcium silicate (0.0; 1.0 and 2.0 mM) and 4 solutions of PEG-6000 to simulate different osmotic potentials (0, 0; -0.3; -0.6; -0.9 MPa). Germination percentage, germination speed index (GSI), mean germination time (MGT), percentage of non-germinated and abnormal germinated, length and dry matter of shoot, root and total seedlings were evaluated. Water deficiency reduced the parameters TG, GSI and MGT. The water deficit reduce the MSPA, MSR and MST with more than 80% reduction in mass from seedlings without deficiency to seedlings with deficiency. For CPA, CR and CT there was a reduction of at least 87%, 70% and 77%, respectively, among seeds without deficiency compared to seeds submitted to deficiency. The use of silicon in corn seeds did not attenuate the stress caused by water deficit simulated by PEG-6000.