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Influência da época e do número de desrama sobre o desenvolvimento inicial de Tectona grandis l. F. no sistema silvipastoril Influence of season and number of landslides on initial development of Tectona grandis l. F. in silvopastoral system

The efficiency of broadcast versus in line phosphate fertilization has been studied; however, soil density as a determining factor for soil efficiency has been less studied. Thus, the objective of this study was to evaluate the effect of broadcast and in line phosphate fertilization in soil with different densities on corn development. The experiment was conducted in pots under greenhouse condition. A completely randomized design was used in a 2x3 factorial arrangement with four replications. Treatments were two levels of soil densities (1.2 and 1.6 g cm-3) and three forms of P application (broadcast, in line and without P). Corn stem diameter, plant height, root volume, root and shoot dry matter, and root and shoot phosphorus content and accumulation were evaluated. Application in line resulted in higher P accumulation by corn plant. There was higher plant dry matter accumulation at soil density 1.2 g cm-3 than at 1.6 g cm-3. Phosphate fertilization in line at soil density 1.2 g cm-3 enhances dry matter accumulation in corn plants.

The objective of this study was to verify and compare the P availability in an Oxisol cultivated with Megathyrsus maximus cv BRS-Zuri and Urochloa decumbens cv Basilisk and to predict the best soil P extractor in pastures in Southern Amazonia. Two experiments were carried out, one with BRS-Zuri grass and the other with Signal grass. The experimental design was randomized blocks with five doses of P2O5 based on the maximum capacity of adsorption of P (MCAP), corresponding to 0, 3, 6, 12 and 24% MCAP, with doses 0, 54, 108, 216 and 432 kg ha-1 of P2O5, with four replicates. In each cut of the grasses were determined the dry mass, the accumulation of leaf P and by the Mehlich-1 and resin extractors verified the available P. There were effects of P2O5 doses on the variables analyzed in both grasses. The appropriate class of P by Mehlich-1 was 14.6 mg dm-3 (BRS-Zuri) and 7.2 (U. decumbens) mg dm-3, by the resin extractor was 20.5 mg dm-3 (BRS-Zuri) and 14.40 mg dm-3 (U. decumbens). The resin extractor yielded the highest correlation indexes between PR and soil P content.

Studies of the dynamics of water in the Soil-Plant-Atmosphere system have been constantly carried out, as they directly contribute to the increase in production and the rational use of water for the most diverse cultures. In this approach, the aim of the study was to assess the water demand in forage Urochloa decumbens, with application of the SIMDualKC model. The meteorological variables used in the paper were obtained by an automatic INMET station. And to estimate forage production, cuts were made at a height of 15 cm, then removing it, simulating cattle grazing. In each cut, the accumulation of degree-days was determined and the base and cut temperatures were 10°C and 30°C, respectively. For the dynamics of crop water demand, the SIMDualKc model was used, in a daily time interval to estimate the basal crop coefficient (Kcb), evaporation coefficient (Ke), crop evapotranspiration (ET), in addition to Kc and the water available in the soil in the forage growing cycle. Kcb and Ke had an inverse relation, which means that when Kcb increased, Ke showed a decreasing trend. The Kc values did not change until the 3rd cut, but in the 4th cut there were changes with a reduction in rainfall and water availability in the system. It is observed that the model showed good ability to estimate the amount of water available in the soil, in addition to the physiological attributes of the forage, being a great option in the study of water dynamics for the forage.

Studies of the dynamics of water in the Soil-Plant-Atmosphere system have been constantly studied, as they directly contribute to the increase in production and the rational use of water for the most diverse cultures. In this approach, the aim of the study was to assess the water demand in forage Urochloa decumbens, with application of the SIMDualKC model. The meteorological variables used in the paper were obtained by an automatic INMET station. And to estimate forage production, cuts were made at a height of 15 cm, then removing it, simulating cattle grazing. Each cut was determined to accumulate degree-days and the base and cut temperatures were 10°C and 30°C, respectively. For the dynamics of crop water demand, the SIMDualKc model was used, in a daily time interval to estimate the basal crop coefficient (Kcb), evaporation coefficient (Ke), crop evapotranspiration (ET), in addition to Kc and the water available in the soil in the forage growing cycle. Kcb and Ke had an inverse relationship, which means that when Kcb increased, Ke showed a decreasing trend. The Kc values did not change until the 3rd cut, but in the 4th cut there were changes with a reduction in rainfall and water availability in the system. It is observed that the model showed good ability to estimate the amount of water available in the soil, in addition to the physiological attributes of the forage, being a great option in the study of water dynamics for the forage.

Background and aims: The importance of boron (B) in the growth and development in native tree species are relevant to establish quality indexes for seedlings. The objective of the present study was to evaluate the effect of boron application on the development of Dipteryx odotara seedlings. Methods: The experimental design was a completely randomized design, five treatments with four replications. The treatments consisted of B doses, in the form of boric acid (17% of B), being: 0; 1.0; 10; 20 and 40 mg B kg-1. We evaluated the seedlings were at 60 days after transplanting. Results and Conclusions: The dose 1 mg B kg-1 and absence of application in Dipteryx odotara seedlings provided the highest values ​​of stem diameter, shoot height, root volume and dry mass of shoot, root and total. It also provided better quality indexes for seedlings: shoot height/shoot dry matter, shoot dry mass/root dry mass and Dickson quality index, did not show symptoms of B toxicity in plants. Unlike the other doses that affected the growth and development of Dipteryx odotaraseedlings.

Jenipapo (Genipa spruceana) is a native species of the Amazon that has great potential in producing seedlings for reforestation. This study aimed to evaluate the effect of nutrient doses applied through fertigation on the quality of Genipa spruceana. The experimental design was completely randomized with five replications, totaling seven treatments. The treatments were: control (without fertilization); 900 mg N L-1 and 750 mg K L-1 with and without micronutrients; 1800 mg N L-1 and 1500 mg K L-1 with and without micronutrients, 3600 mg N L-1 and 3000 mg K L-1 with and without micronutrients. The experiment was conducted in a greenhouse for 35 days. Then, the following variables were evaluated: stem diameter, height, root and shoot dry matter, and total dry matter. From these measurements, the following ratios were calculated: height/stem diameter, height/shoot dry matter, shoot dry matter/root dry matter, and Dickson quality index. Weekly fertigation applying 1800 mg N -1 and 1500 mg K L-1 provided the best Dickson Quality Index of Genipa spruceana seedlings. The hypothesis of the present study was confirmed, and the Genipa spruceana did not have a tolerance to high N e K fertilization.