Luminosity and temperature are factors that directly act in photosynthetic process, in which the elevation of the light intensity may provoke reduction in the assimilation of carbon, impairing the development of the soybean culture. This work aimed to know physiological parameters of soybean (Glycine max L. Merr.) under different intensities of artificial light. The experiment was carried out in randomized blocks, in a factorial scheme 2 × 5, being two soybean cultivars (Potência and NS6700) and five densities of light: 0 (control), 500, 1000, 1500 and 2000 μmol m-2 s-1 of photosynthetically active radiation (PAR) provided by LED bulbs, with 4 repetitions, in total of 40 plots. The following variables were set: rate of CO2 assimilation (A), transpiration (E), stomatal conductance (gs), inner CO2 concentration in the substomatic chamber (Ci) and water use efficiency (WUE) in which a portable device of gas exchange was used (Infra-Red Gas Analyzer-IRGA, marca ADC BioScientific Ltd, modelo LC-Pro). Seedlings of soybean positively responded under different intensities of artificial light till reach the maximum saturation point between 1400 and 1600 µmol m-1 s-1 of light, which promoted a better rate of A, Ci andWUE. E and gs presented positive linear responses by increasing the intensity of artificial light. The ideal light intensity to the use of Infra-Red Gas Analyzer-IRGA between 1400 and 1600 µmol m-1 s-1 to the soybean culture.
Brazilian soils destined for fodder production are infertile and acidic and contain toxic levels of aluminum (Al), which cause a reduction in growth of the root system and aerial plant parts. The main aim of the present pot trial was to determine ultrastructural and developmental changes in root and leaf tissues of Urochloa brizantha, when grown in an acid Oxisol containing varying levels of Al. The experimental design was a 3 × 5 factorial arrangement, involving 3 cultivars of U. brizantha (Marandu, Paiaguás and Piatã) and 5 concentrations of Al in the soil (0.2, 0.4, 0.8, 1.6 and 3.2 cmol/dm3), with 4 replications; a total of 60 pots. All cultivars responded negatively to increasing Al concentration in the soil, even in small amounts. Root ultrastructures were damaged even at concentrations of 0.4 cmol Al/dm3, primarily in the conducting tissues (xylem and phloem) and epidermal cells. Shoot development and leaf tissues were also negatively affected. In general, plant development and ultrastructure of root and leaf tissues in all 3 cultivars of U. brizantha were impaired when grown in the presence of Al at doses >0.2 cmol/dm3 in the soil.
Brazilian soil presents serious problems with plant production, due to its low fertility and high acidity content, besides that the toxicity caused by the chemical element aluminum. To overcome these problems, agricultural gypsum is used to neutralize the action of aluminum and, together with the assistance of nitrogen sources, ensures greater forage productivity. The objective of this work was to recover a pasture area with the application of agricultural gypsum associated with nitrogen fertilization. The experimental design was in randomized blocks with four replications, in a 2x4 factorial scheme with 50 kg ha-1 of N in the form of ammonium nitrate and 50 kg ha-1 of N in the form of urea, plus four doses of agricultural plaster, of which: 0; 750; 1500 and 3000 kg ha-1 in pasture installed in Urochloa humidicola. The dose of 1884 kg ha-1 of gypsum provided the highest concentration of calcium when applied in conjunction with ammonium nitrate. For sulfur, a linear response was observed, regardless of the nitrogen source used. The use of urea significantly increased the nitrogen levels in the leaves. The application of gypsum, regardless of the nitrogen source, provided a linear response in the calcium and sulfur levels in the leaves.
Introduction:In order to characterize Eucalyptus species for diverse purposes, it is necessary to analyze it in an ultrastructural and physiological way, aiming a faster and more precise selection of the possible properties and utilities of the species. Objective: The objective was to observe the physiological and ultrastructural characteristics of leaves of eucalyptus clones destined for matrix selection.
O objetivo do trabalho foi avaliar a influência do composto orgânico bokashi no desenvolvimento da alface americana. O experimento foi conduzido em Andradina-SP. Utilizou-se o esquema de blocos casualizados, com 2 tratamentos e 8 repetições, constituídos de uma dosagem de bokashi de 0,5kg/m2 e nenhuma aplicação (controle). Foram confeccionados 8 canteiros em área anteriormente em pousio, sem nenhum emprego de adubação. O bokashi foi distribuído e incorporado uniformemente nos canteiros, em uma única vez e no tratamento controle não foi efetuada nenhum tipo de adubação. Em cada canteiro foram transplantadas 20 plantas. Avaliou-se na época da colheita o desenvolvimento radicular da planta, o peso fresco da planta, o peso fresco e seco da raiz e comprimento de raiz. Os dados foram submetidos à análise de variância e as médias foram comparadas pelo Teste de Tukey a 5% de probabilidade, utilizando o programa estatístico AgroEstat. O peso fresco da planta foi á única variável analisada que apresentou diferença estatística significativa. Concluiu-se que a utilização do bokashi proporcionou maior peso fresco de plantas. Ao fazer o uso dessa prática orgânica obtêm-se vantagens ecológicas e econômicas, dando preferência em produzir o composto na propriedade, visando reduzir os custos da produção.
The presence of toxic aluminum in the soil and N deficiency are one of the main causes of degradation of cultivated pastures, mainly of the Urochloa genus. The use of agricultural gypsum for restoring soil fertility is one of the ways to recover the productive capacity of degraded areas. Given the above, the work aims to assess pasture recovery with the application of agricultural gypsum associated with nitrogen fertilization. The experimental design was randomized blocks in a 3x4 factorial arrangement, that is, absence of nitrogen, 50 kg ha-1 in the form of ammonium nitrate and 50 kg ha-1 urea, interacting with four doses of agricultural gypsum, namely: 0 ; 750; 1500 and 3000 kg ha-1 and with four replications, totaling 48 plots. The use of urea as a source of N resulted in a higher plant height (PH) when compared to the use of ammonium nitrate, representing a relative increase of approximately 12% in relation to the control. Dose of 1730.8 kg ha-1 of agricultural gypsum resulted in a maximum production of 4.97 t ha-1 of dry pasture. The linear interaction of the use of ammonium nitrate with gypsum doses shows an extremely interesting synergistic potential with this source. For dry mass of culms (CDM), the use of urea had a PMTE of 1730.8 kg ha-1 of agricultural gypsum resulting in 2.38 t ha-1. The culms dry mass of (CDM) represented 47.9% of the total dry mass of the pasture.
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