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-The objective of this work was to evaluate the physiological behavior at different times of the day and the level of dependence between physiological variables and meteorological elements in Aleurites fordii seedlings. The experiment was conducted in a greenhouse, using a completely randomized experimental design, in a uniform scheme composed of 10 evaluation times (from 8 am to 5 pm, with an interval of 1h between evaluations) and three replications. Each replicate consisted of three evaluation plants, totaling nine seedlings, which were arranged on a double border. The following characteristics were evaluated: leaf temperature (°C), photosynthetically active solar radiation (mol S -1 m -2 ), stomatal resistance (S cm -1 ), and transpiration (mmol H 2 O s -1 m -2 ) over a typical day, using a LI-1600 LI-COR digital porometer. The temperature and relative humidity were measured inside the greenhouse, using a thermohygrograph. The evaluations were performed at 244 days after sowing, between 8:00 and 17:00, with an interval of 60 minutes, totaling 10 evaluations. The physiological changes of Aleurites fordii seedlings are affected by the time of day. In general, the physiological variables are highly dependent on meteorological elements. The temperature of the greenhouse and the relative humidity are the meteorological elements that most influence the physiological behavior of Aleurites fordii seedlings.Keywords: Transpiration; Stomata; Photosynthetically active solar radiation. RELAÇÕES FISIOLÓGICAS EM MUDAS DE Aleurites fordii Hemsl.RESUMO -O trabalho teve como objetivo avaliar o comportamento fisiológico em diferentes horários do dia e o nível de dependência entre variáveis fisiológicas e elementos meteorológicos em mudas de Aleurites fordii. O experimento foi conduzido em casa de vegetação, utilizando-se delineamento experimental inteiramente casualizado, em esquema unifatorial composto por 10 horários de avaliação (das 8 às 17h, com intervalo de 1h entre as avaliações) e três repetições. Cada repetição era constituída por três plantas de avaliação, totalizando nove mudas, as quais estavam dispostas sobre bordadura dupla. Foram avaliadas as características: temperatura da folha (°C), radiação solar fotossinteticamente ativa (ìmol S -1 m -2 ), resistência estomática (S cm -1 ) e transpiração (mmol H 2 O s -1 m -2 ) ao longo de um dia típico, com uso de um porômetro digital LI-1600 LI-COR. As medidas da temperatura e umidade relativa do ar foram determinadas dentro do ambiente protegido, utilizando-se um termohigrógrafo. As avaliações foram realizadas aos 244 dias após a semeadura, entre 8:00 e 17:00h, com intervalo de 60 minutos, totalizando 10 avaliações. O comportamento fisiológico das mudas de Aleurites fordii é afetado pelo horário do dia. De modo geral, as variáveis fisiológicas estudadas são altamente dependentes dos elementos meteorológicos. A temperatura do ambiente protegido e a umidade relativa do ar são os elementos meteorológicos que mais influenciam o comportamento fisiológico das mudas ...

Environmental conditions affect crop yield, and water deficit has been highlighted by the negative impact on soybean grain production. Radicial growth in greater volume and depth can be an alternative to minimize losses caused by a lack of water. Therefore, knowledge of how soybean roots behave before the chemical, physical, and biological attributes of the soil can help establish managements that benefit in-depth root growth. The objective was to evaluate the growth of soybean roots in response to chemical, physical, and biological variations in the soil, in different soil locations and depths. Six experiments were conducted in different locations. Soil samples were collected every 5 cm of soil up to 60 cm of soil depth for chemical, physical, and biological analysis. The roots were collected every 5 cm deep up to 45 cm deep from the ground. The six sites presented unsatisfactory values of pH and organic matter, and presented phosphorus, potassium, and calcium at high concentrations in the first centimeters of soil depth. The total porosity of the soil was above 0.50 m3 m−3, but the proportion of the volume of macropores, micropores, and cryptopores resulted in soils with resistance to penetration to the roots. Microbial biomass was higher on the soil surface when compared to deeper soil layers, however, the metabolic quotient was higher in soil depth, showing that microorganisms in depth have low ability to incorporate carbon into microbial biomass. Root growth occurred in a greater proportion in the first centimeters of soil-depth, possibly because the soil attributes that favor the root growth is concentrated on the soil surface.

The aim was to evaluate the interactive effects on biochemistry and physiology of soybean plants exposed to simultaneous xenobiotic and water deficit stresses, and the possible attenuation of plant damage by an antioxidant agent. Soybean plants were submitted to eight different soil water potentials, in two experiments (first experiment: −0.96, −0.38, −0.07, −0.02 MPa, and second experiment: −3.09, −1.38, −0.69, −0.14 MPa), xenobiotic, and antioxidant agent applications. Was observed a reduction in water status, gas exchange, photosynthetic pigments, photosystem II quantum yield, and increased leaf temperature in plants under low water availability. Water deficit also induced oxidative stress by the increased production of reactive oxygen species, cellular and molecular damage, and induction of the antioxidant defense metabolism, reduction of gas exchange, water status, and photosynthetic efficiency. The xenobiotic application also caused changes, with deleterious effects more pronounced in low soil water availability, mainly the reactive oxygen species production, consequently the antioxidant activity, and the oxidative damages. This indicates different responses to the combination of stresses. Antioxidant enzyme activity was reduced by the application of the antioxidant agent. Principal Component Analysis showed a relation with the antioxidant agent and reactive oxygen species, which is probably due to signaling function, and with defense antioxidant system, mainly glutathione, represented by thiols.

The objective of this paper was to assess the efficiency of photosynthetically active radiation (PAR) intercepted in dried phytomass of soybean cultivars of determinate and indeterminate growth habits in different spatial arrangements. All experiments were carried out during the 2013/2014 crop year, two soybean cultivars (BMX Ativa RR/determinate and BMX Turbo RR/indeterminate) in a spatial arrangements (45, crossed, 20, 20 × 40, 20 × 60, 20 × 80 cm). Starting from first emergence up to the point of maturation, 14 phytomass assessment were evaluated with seven days interval, in which one plant was sampled per repetition. Greater conversion efficiencies of solar radiation were obtained in paired arrangements. Paired arrangements, and 20 cm, lead to a greater leaf area index, and possibly a greater interception of the diffused radiation and an increase of conversion efficiency and the overall cultivation productivity of BMX Ativa RR and BMX Turbo RR.

Chemical, physical and biological soil attributes can facilitate soybean root growth in greater volume and depth in the soil, which can minimize yield reduction caused by water deficit. Soil management can contribute positively or negatively to these soil attributes. The aim of this work was to evaluate the root growth and crop performance of soybean, in response to chemical, physical and biological changes after subsoiling at different depths. At the R5 phenological stage, trenches were made for sampling and soil collection for chemical, physical and biological analysis and root growth was carried out. At V5, V7, R2 and R5 stages, plants were collected to evaluate height, leaf area and dry mass. At V5, stage number and dry mass of the nodules were evaluated. Subsoiling increased pH and Ca, and decreased Al in the soil, resulted in higher relative density and did not affect in mechanical penetration resistance compared to non-subsoiled soil. Basal respiration and soybean nodulation were higher in the subsoiled soil. Up to 15 cm depth, there were 87.91% of the total root dry mass and 78.79% of the total root volume. Initial and final plant growth were the same in subsoiled and non-subsoiled soil. Number of nodules in the subsoiled soil was 28% higher than in the non-subsoiled soil. Under these study conditions, subsoiling provides lower root growth but benefits grain yield.

The purpose of this study is to determine the growth, the solar radiation use efficiency, and the gross protein of sorghum forage under different cutting management. A unifactorial design in random blocks (cutting management) was used, varying from no-cut treatment to four cuts. The first cut occurred 44 days after sowing, the second one after 23 days of regrowth, the third one after 25 days of regrowth, and the last one after 40 days of regrowth. The efficiency of the sorghum forage's solar radiation use reduces as the number of cuts increases. The sorghum forage's gross protein increases with cutting management. Therefore, for a sorghum forage crop, it is recommended to restrain the cutting management up to three times during the crop cycle, since it has the biomass potential production, and the cuts should be made at every 25 days, depending on the increase of dry mass. After that, the cutting management should not be done, mainly due to the low radiation use efficiency, reduced dry mass accumulation, and low material quality.

Nossa hipótese é que o sorgo forrageiro modifica seu crescimento e filocrono quando é submetido a diferentes manejos de corte. Nosso objetivo é avaliar se diferentes manejos de corte modificam o crescimento e filocrono do sorgo forrageiro. Um experimento de campo foi conduzido e submeteu o sorgo forrageiro a diferentes manejos de corte: sem corte, 1 corte, 2 cortes, 3 cortes e 4 cortes. Foram avaliadas as condições ambientais durante o ciclo da cultura, as taxas de crescimento da cultura, a distribuição dos fotoassimilados e o filocrono. A temperatura influenciou o crescimento e o desenvolvimento da cultura. Os fotoassimilados foram alocados de acordo com a necessidade da cultura, determinada pelo seu estádio de desenvolvimento. Plantas que não sofreram cortes tenderam, em geral, reduzir as taxas ao longo do tempo, devido ao desenvolvimento fisiológico. Enquanto que as plantas que foram cortadas, tiveram seu ciclo prolongado, pelo rebrote, e algumas taxas diminuíram após cada corte, pela remoção do material vegetal, como por exemplo, a taxa de crescimento absoluto, a taxa de assimilação líquida, a razão de área foliar e a razão de peso foliar. Aumentos no filocrono foram observados com o aumento no número de cortes.