Residues from agricultural activities might be used as substrates for production of seedlings. In this study it was aimed to evaluate the physiology, nutrition and quality of Eugenia dysenterica DC. seedlings grown in substrates derived from agricultural organic wastes. The wastes used were as follows: rice husks (RHs); fermented cattle manure (FCM); cattle manure compost (CMC), which contained corn silage and FCM; sugarcane bagasse (SCB); filter cake from sugar-alcohol mills (FC); and subsoil (SB). Four substrates were formulated from the wastes, namely SB+RH (1:1; v:v), SB+CMC (1:1), SB+FCM (3:1) and SCB+FC (3:2) and BioplantÒsubstrate was also used. The following characteristics were evaluated: the emergence and vigor percentages, biometric characteristics, seedling quality indices, gas exchange, chlorophyll a fluorescence and leaf nutrient levels. The seedling emergence was similar for all the substrates. The highest vigor was found in seedlings that were cultivated in SCB+FC, which was equal to the vigor observed in BioplantÒ. In general, the use of the SB+CMC substrate gave better seedling results for the biometric and nutritional characteristics, followed by SCB+FC. Most of the biometric characteristics showed a correlation with photosynthesis, electron transport rate and effective quantum yield of photosystem II, thus showing that these characteristics can be alternatives to the traditional quality indexes used for seedlings. The use of CMC, SCB and FC was shown to be appropriate for the production and nutritional supply of seedlings’ specie. The composition SB (subsoil)+CMC (1:1) proved to be the most suitable to produce E. dysenterica seedlings.

Indicadores preliminares para avaliação da restauração em reflorestamentos de ambientes ciliares

The production of high-quality seedlings and their use in commercial planting reduce pressure on natural areas. Eugenia dysenterica DC is a native fruit tree from the Brazilian Cerrado, whose nutritional requirements are still unclear. This study aimed to evaluate the effects of nitrogen (N) and phosphorus (P) supplementation on the physiology, growth and nutrient uptake, and use efficiencies of E. dysenterica seedlings grown in glasshouse conditions. The following rates were used in separate experiments: 0, 50, 100, 200, and 400 mg dm⁻³ N and 0, 100, 200, 400, and 600 mg dm⁻³ P. The experiment was conducted in a randomized block with four replications. The lowest N rate (50 mg dm⁻³) increased the stomatal conductance (g_S) and, consequently, resulted in the highest transpiration (E), electron transport (ETR), and photosynthetic (A) rates. Also, rates of 50 mg dm⁻³ and 100 mg dm⁻³ N increased the Root Uptake Efficiency (RUE) and plant Nutrient Use Efficiency (NUE) for macronutrients and the RUE for micronutrients, stimulating plant growth. Phosphorous fertilization resulted in the maximum values for photosynthesis, electron transport rate, total dry mass, and NUE at the 200 mg dm⁻³ rate. The results of this study suggest that fertilization with 50 mg dm⁻³ N and 200 mg dm⁻³ P is suitable for the development of E. dysenterica seedlings.

Knowledge of a rock’s composition allows for inferences regarding several properties, ranging from its physical characteristics to its solubility. This study aimed to evaluate the use of different extractants to solubilize the K present in rocks as a potential source of nutrients and the effects of extractant contact time and temperature on rock solubilization. Samples of two rocks and a mineral concentrated from a granitic rock were treated with ammonium dihydrogen phosphate (NH₄(H₂PO₄)), calcium dihydrogen phosphate (Ca(H₂PO₄)₂), sodium hydroxide (NaOH) and water (control). Sample-extractant treatments were performed using a water bath shaker at temperatures of 25 and 50°C for periods of 3, 7, 10, 20, and 30 days. The amounts of K extracted from rocks using the extractants were in the following order: NH₄H₂PO₄>Ca(HPO₄)₂>NaOH>water. The sequence of K release (ppm) based on the rocks studied was as follows: nepheline syenite>green banded argillite>concentrated biotite. Increasing the extractant contact time and temperature enhanced the solubilized K content.