Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The objective of this work was to evaluate the effect that different irrigation depths on the growth and crop production of jambu plants. The treatments consisted of five irrigation depths corresponding to 40%, 70%, 100%, 130% and 160% of field capacity. The experimental design was a randomized blocks with four replications. The plot consisted of four plants in separate pots. For comparison of treatments, at 27 days after transplantation, the following variables were analyzed: plant height (PH), stem diameter (SD), leaf fresh matter (LFM), stalk fresh matter (SFM), root fresh matter (RFM), inflorescence fresh matter (IFM), leaf dry matter (LDM), stalk dry matter (SDM), root dry matter (RDM), inflorescence dry matter (IDM) and water use efficiency (WUE). The effect of irrigation depths was significant for the analyzed variables, except for the SD and IDM. There was a quadratic behavior of the variables in relation to the applied irrigation depths. The maximum values of each parameter were obtained with irrigation depths close to 100% field capacity. Although the efficiency of water use was higher for the irrigation depth of 40% of field capacity, It is most recommended to use the irrigation depth at 100% of field capacity, because it provided the best answers of the variables analyzed.

A prediction equation that establishes the relationship between pressure and gas volume can replace manual volume readings. This study serves to determine a prediction equation that correlates values of pressure and volume of gases for use in food evaluation by the semi-automatic in vitro gas production technique. The following was used with experimental diets 3 different ratio roughages: concentrate (100:0, 50:50 and 75:25) containing Mombaça grass silage and a commercial concentrate, and four levels of Propylene Glycol (PG) (0%, 2%, 4% and 6% of the volume of content to be incubated). A total of 1 g of each diet was incubated in 150 mL flasks with 90 mL culture medium, 10 mL ruminal inoculum, and the appropriate PG levels (two repetitions per diet). Gas pressure and volume readings were taken using a transducer. The data were used in the regression analysis, resulting in the estimation of gas volume from the pressure. The generated equation volume as a function of pressure presented curve with quadratic behavior was (V = –0.0195 + 3.7989P + 0.2174P2). The coefficient “b” of the second degree function multiplied by pressure (P) was 3.7989 at an altitude of 240 m. Local altitude influences the relationship between pressure and gas volume.

Organic waste can be used in the production of forest seedlings, providing a high index of nutrients for them and contributing to the environment because it is a reused residue. Thus, this study aimed to evaluate the use of combined substrates with sewage sludge and water blades in embaúba seedlings. Treatments were: T1: 100% commercial substrate (CS), T2: 100% composted sewage sludge (CSS), T3: 75% CS and 25% CSS, T4: 75% CSS and 25% CS, and T5: 50% CSS and 50% CS. Three types of irrigation were provided four times a day, and the amount of water was: L1 – 9 mm, L2 – 18mm, and L3 – 27 mm. The evaluated parameters were plant height, leaf diameter, number of leaves and dry mass production. Results showed that the formulation of CSS and CS helped the development of the evaluated parameters. The best treatments found were T3 and T4 along the water blade 3.

The management of weeds in the soybean crop, by reducing the planting spacing, is an important grown factor on which the success of production depends. The objective of this study was to evaluate the floristic, ecological and phytosociology composition of weeds in soybean grown under different spacing in Amazonian savanna area, Boa Vista, RR, Brazil. Thus the BRS 7980 soybean cultivar was sown in a conventional system, in four blocks, using three rows spacing (45, 55 and 65 cm). The weeds sampling was performed using an iron square (0.25 m2), which was thrown randomly four times in each block, totaling 4.0 m2 of sampled area. A total of 16 weed species were recorded, distributed in ten genera and five families, of which Fabaceae and Malvaceae predominated. Four species were present in all spacings: Mimosa pudica L., Urochloa decumbens Stapf., Calopogonium muconoides Desv. and Waltheria communis A.St.-Hil. The different spacings were not indicators of the floristic composition of weeds. The low index of similarity between species indicates that the plant community was affected by the different spacing. Urochloa decumbens Stapf. obtained greater prominence in the evaluated phytosociology parameters, requiring special attention in the control. The largest dry weed mass was obtained in the 55 and 65 cm spacing. The predominant type of propagation, life form and life cycle were by seeds, grass and perennial, respectively. The predominant photosynthetic route was type C3, especially at 45 cm. Therefore, the grown of soybean in 45 cm spacing between rows causes a reduction in the ecology and phytosociology composition of weeds in Amazonian savanna area. The different spacing between rows is not an indicator of the floristic composition of weeds in soybean cultivation in the Amazonian savanna.

In pastures, trees and shrubs, remaining from original forest or the rain of seeds, are part of spontaneous plants; in this background they are considered competitors that weaken a forage or may be responsible for a balanced dynamic, decreasing the density of competing plants. The aim of this study was to describe the structure and floristic composition of spontaneous pasture plants and to verify the influence of forage species and the presence of woody plants existing above the herbaceous stratum, besides investigating the presence or not of infestation along the BR-156 highway, in the municipality of Oiapoque, Amapá state, Brazil. Thirty-one pastures were sampled on smallholder family farms; these were categorized according to: (1) the forage species (Urochloa brizantha cv. Marandu and U. humidicola); (2) and the presence of woody plants (clean or dirty pastures) above the herbaceous stratum. In each area, the floristic survey was performed in a 1 x 50 m (50 m2) transect, where all individuals with 0.10 ≤ height < 2.0 m were inventoried. A total of 90 species were recorded, predominantly herbaceous. The floristic composition of spontaneous plants is very similar to those found in other pastures of the Amazonia, however several pastures showed infestation by some species, such as Stigmaphyllon convolvulifolium, Stigmaphyllon sinuatum, Borreria verticillata, Hyptis atrorubens, Desmodium barbatum, or Stachytarpheta cayennensis. The structure and floristic composition of spontaneous plants is not influenced either by forage or by the presence of woody plants existing above the herbaceous stratum.

The investigation of the biomass quality in the fresh condition and after storing environmental conditions is necessary to support its usage for energy generation. In Amazonia, the waste produced from açaí depulping stands out because of its wide availability. This work aimed to evaluate if the different methods and sites of storage modify the physical, chemical, and energetic properties of the açaí waste and its potential for energetic purposes. The residues were collected at Macapá, Amapá state, in six different conditions: a fresh sample, obtained right after depulping, and five samples stored under different environmental conditions. After depulping, the açaí waste showed a moisture content of 103.8%, but the storage resulted in natural drying, reducing this property to up to 12.3%. Compared with the fresh waste (0.719 g cm-3), the basic density of the wasteland-dispersed biomass decreased significantly (0.279 g cm-3), which reduces the yield of combustion and pyrolysis. When the wastes were stocked, volatile materials raised from 65.29% to 75.62%, fixed carbon decreased from 34.70% to 23.09%, and ashes content reduced from 1.81% to up to 1.24%. Such modifications suggested the partial decomposition of chemical components that became volatile or leachable. Consequently, the storage decreased the higher heating value and the energy density of the wastes.  It was concluded that açaí waste storage by any condition, except for moisture content decreased, harmed its energetic potential.

The need to improve silvicultural techniques, which can contribute to increasing forest productivity, arises due to the growing demand for products derived from wood. The mineral fertilization is highlighted as essential among factors that influence the initial growth of plants, the reason why the knowledge on the nutritional requirements of forest species is found to be important. The objective of this work was to evaluate the effect of micronutrient omission on biometric parameters in seedlings of Acrocarpus fraxinifolius Wight & Arn., (Indian cedar) grown in nutrient solution. The study was established in a completely randomized design, with seven treatments, four replications and one plant per pot. Treatments consisted of the complete solution of nutrients Hoagland and Arnon and omission of the following selected micronutrients: boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn). At 90 days after transplantation, the following biometric parameters were evaluated: height of the shoot, diameter of the stem, dry mass of the shoot and root. The visual symptoms of micronutrient deficiency were also evaluated, as well as the content and accumulation of nutrients in the aerial part of the seedlings. The deficiency of micronutrients in the nutrient solution, showed a negative effect on the growth of seedlings of Acrocarpus fraxinifolius Wight & Arn. The limiting micronutrients in the growth of Indian cedar seedlings in decreasing order were Fe>Cu>B>Mn>Mo>Zn.

A large part of Brazil nut production comes from extraction in native areas. Thus, the successful exploitation in cultivation systems is highly dependent on vegetative propagation techniques, to maintain the genetic traits and shorten the juvenile period of selected genotypes. This study aimed to determine the optimal age of Brazil nut rootstocks to perform grafting by patch budding method, as well as to verify the percentage of graft survival and the initial growth of different clones in Roraima. For this purpose, two experiments were installed in a randomized block design, with four replications. The treatments were arranged in a split-time scheme in time, such as the genotypes considered the plots and the evaluation times the subplots. It were evaluated rootstock growth traits, percentage of alive grafts and sprouts growth traits. The rootstocks reached the recommended size for grafting between 26 and 34 months after planting, indicating slower growth when compared to other locations. At 120 days after grafting, it were obtained percentages of graft survival ranging from 25% to 100%, depending on the graft genotype. The overall average percentage of survival was over 70%. The initial growth (height, diameter and number of lateral shoots) of shoots observed for some genotypes is indicative of their adaptation to the cultivation conditions considered. As the Brazil nut tree is a perennial species, both the growth in older ages, as well as the future productivity and longevity of the plants must be monitored.

Nitrogen utilization by maize is dependent on the rate and time at the nutrient is supplied. The objective of this study was to evaluate the maize morphological and productive aspects in a clayey Oxisol. The experiment was carried out under field conditions in the Iraí de Minas - MG in irrigated area. A randomized complete block design was used in a 5 x 2 + 1 factorial scheme, with four replications. The treatments consisted of five N rates (0, 50, 100, 150 and 200 kg ha-1) associated with two application times (pre-sowing and sidedressing) and an additional treatment referring to the fertilization adopted by the farm. The pre-sowing application was performed 15 days before sowing and the sidedressing when the plants had 4 - 5 fully expanded leaves. The farm fertilization consists of the 35 kg ha-1 of N, 139 kg ha-1 of P2O5 and 70 kg ha-1 of K2O at sowing and two applications of 50 kg ha-1 of N in sidedressing, the first was performed 17 days after the plants emergence and the second 10 days after the first application. Urea was used as the source of N. It was concluded that the N application in pre-sowing was efficient under the edaphoclimatic conditions considered. The N rate of 200 kg ha-1 provided the highest crop yield.

The coffee culture in Brazil has much economic importance and relevance in the social sector. One of the possible reductions of its productivity is due to the injury caused by the insect Coccus viridis (cochineal-green). The plants when being injured are able to increase the synthesis of protease inhibitors (PIs) throughout their extension. Studies have shown that insects fed with plants previously sprayed with synthetic inhibitors have their development affected. Thus, the present work aimed to evaluate the effects of synthetic protease inhibitors, benzamidine and berenil, on the intestinal proteolytic activity of C. viridis. Coffea arabica plants were infested with C. viridis nymphs and sprayed with benzamidine and berenil in four different concentrations: 0; 0.25%; 0.5% e 0.75% (p/v). The insect’s biochemical response was evaluated after 24 h of spraying, and the insects were collected. The activity of the serine proteases, trypsin-like (amidásica and esterásica) and chymotrypsin-like esterase, was reduced due to the presence of the inhibitors. The same was obtained in relation to the activity of cysteine proteases.