Dry Mass Production Research Articles

Root exudation of glyphosate in Eucalyptus urophylla S.T. Blake

Glyphosate stands out in the eucalyptus management, which makes it essential to know its behavior, its effects on the plant, and possible environmental impacts. This study aimed to identify and quantify the root exudation of glyphosate and aminomethylphosphonic acid (AMPA) by Eucalyptus urophylla with chromatographic and biological methods. The five glyphosate doses were tested (0, 360, 720, 1080 and 1440 g a.e ha−1) on E. urophylla plants. The physiological and intoxication evaluations were performed after herbicide application. Water samples remaining from the pots were used for chemical quantification of root exudation of glyphosate and AMPA in high-performance liquid chromatography. Cucurbita pepo plants were used as bioindicators of glyphosate in the water remaining in the pots after applying herbicide. The increase in glyphosate doses promoted linear growth in E. urophylla intoxication and significantly reduced total dry mass and root production. E. urophylla plants had their photosynthetic, transpiratory, and stomatal conductance rates reduced as the herbicide doses increased. The AMPA root exudation was not detected, but it was possible to identify the presence of glyphosate by bioassay and chemical methods. Root exudation of glyphosate by eucalyptus can result in lesser herbicide action in plant control and cause contamination of deeper soil layers.

Elephant Grass Cultivar BRS Capiaçu as Sustainable Biomass for Energy Generation in the Amazon Biome of the Mato Grosso State

Sustainable biomasses are vital to ensure preservation of the Amazon biome within the Mato Grosso State whilst enabling energy generation for the region and its population. Here, the potential of the elephant grass cultivar BRS Capiaçu as an alternative to replace native forest wood as biomass for energy generation is investigated, considering the whole process from plant cultivation to biomass characterisation in terms of productivity of green and dry mass per hectare; density, moisture, ash, volatile and fixed carbon content, as well as higher heating value (HHV). MANOVA indicates that the effects of plant parts and age on density and proximate analysis parameters are influenced by the plant parts and age interaction, whereas HHV can be considered similar between them. The cultivar BRS Capiaçu showed suitable energetic values (17,922 < HHV < 18,918 kJ.kg−1) compared to that of native Amazon wood. Energetic results combined with cultivation outputs of high productivity (dry mass production of 44.1 tonnes.ha−1 at 180 days) with a short cutting interval (3 months), adaptation to the region’s climate and soil, and the possibility of cultivation in areas currently consolidated for agriculture demonstrate the potential of BRS Capiaçu as biomass to reduce native wood usage and deforestation rates.

Maize intercropped with Panicum maximum cultivars and Pigeon pea improves silage yield and quality

Integrated systems are efficient technologies used for diversifying production and promoting agricultural sustainability. The benefits of double intercropping are well-established in research. With advancements in sustainable food production technology, some studies have explored triple intercropping by adding legumes. However, triple intercropping methods must be comprehensively understood. This study aimed to evaluate the production of dry mass, fermentation profile, and nutritive values of silage from maize based intercropping. The experiment was conducted in the field, in Instituto Federal Goiano, Campus Rio Verde, State of Goiás, Brazil, where we assessed silage production and quality in monoculture and intercropping systems, in a randomized block complete design with three replications. We evaluated 8 treatments, consisting of silage from: maize monoculture; Tamani guinea grass monoculture; Quênia guinea grass monoculture; Zuri guinea grass monoculture; Pigeon pea monoculture; maize + Tamani guinea grass + Pigeon pea; maize + Quênia guinea grass + Pigeon pea and maize + Zuri guinea grass + Pigeon pea. The results showed that maize silage intercropped with cultivars of Panicum maximum (Tamani, Quênia and Zuri guinea grasses) and Pigeon pea increased silage mass production by 37.8% and the crude protein content at 25.1% compared with that of the monoculture maize silage. It also improved the fermentation characteristics of silage, reducing 5.1% of pH, 32.5% of buffering capacity, 28.9% of ammoniacal nitrogen in total nitrogen, 15.7% of effluent production, and 20.0% of dry matter losses, compared with those of grass and legume silage in monoculture. Thus, the silage produced by the triple intercropping proved to be an efficient technique for sustainable forage production.

Soil correction, growth, and nutrition of Panicum maximum in response to rates and methods of application of steel slag and limestone

The main objective of this study was to evaluate the effectiveness of a soil conditioner derived from steel slag (Agrosilicio Plus – ASP) compared to dolomitic limestone (DLS) in agriculture. The research questions were about how ASP compares to DLS in terms of soil acidity correction, productivity, and the nutritional status of the forage grass Panicum maximum cv. BRS Zuri. Two experiments were conducted in a greenhouse using plastic pots filled with a 0-20 cm layer of Ferrasol. In the first experiment, soil conditioners were applied on the surface, while in the second, they were incorporated into the soil. A complete block design with a 2 × 4 + 1 factorial arrangement was employed. The factors included two soil conditioners (ASP and DLS) at four application rates (25%, 50%, 100%, and 150% of the liming requirement). A control treatment without any conditioner application was also included. P. maximum was grown in three successive 45-day cropping cycles. The shoot dry mass and nutrient content in plants’ tissues were measured. Both ASP and DLS were effective in correcting soil acidity. The ASP led to a higher silicon accumulation in the plants, whereas DLS resulted in higher calcium accumulation. Increasing rates of both conditioners generally had positive effects on most variables measured. When applied on the surface, ASP led to higher dry mass production accumulated in three crops. ASP is a viable alternative to limestone for correcting soil acidity and supplying essential nutrients and silicon to BRS Zuri grass. Additionally, ASP can effectively be applied on the soil surface.

Use of bacteria solubilizing phosphate, limestone, and phosphate fertilization in tifton 85 pasture

Using inoculants can be an alternative to reduce chemical fertilizers and improve the production of cultivated pastures. The objective of this work was to evaluate the use of an inoculant containing bacteria of the genus Bacillus (Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus pumilus) in a pasture of the genus Cynodon cv. Tifton 85, with and without liming and phosphating. The experiment was carried out in Vista Alegre do Prata, RS, in an area of Tifton 85 established in 2012, organized in randomized blocks with a factorial scheme 2 (with and without inoculant) x 4 (control, liming, phosphating, liming + phosphating), with four repetitions. The parameters evaluated after 49 days were plant height, production of dry and fresh mass of the aerial part, nutrient content in the tissue, neutral detergent fiber (NDF), and acid detergent fiber (ADF). At 119 days, the height of the plants and the production of the dry and fresh mass of the aerial part were evaluated. The results demonstrated that phosphate fertilization and/or liming did not influence the efficiency of using Bacillus spp. The application of Bacillus spp. increased plant height and Tifton's fresh and dry mass in the first cut, but chemical corrections did not affect these parameters. The treatments did not impact forage quality (NDF and ADF). In the second cut, only the height of the plants was greater with the application of the inoculant, suggesting the need for reapplication. Therefore, the application of Bacillus spp. favors the development of Tifton 85, maintaining forage quality.

Unlocking higher yields in Urochloa brizantha: the role of basalt powder in enhancing soil nutrient availability

This study investigates the effect of basalt powder on soil fertility through changes in its chemical characteristics and the response of Urochloa brizantha to different application doses. The experiment was conducted in a greenhouse using two distinct soil types: Oxisol (OX) and Typic Quartzipsamment (TQ). Basalt powder dosages were determined based on the calcium levels required to adjust calcium contents in each soil (Ca2+) to recommended levels for the U. brizantha,ranging from 0 to 4 times the recommended amount. After 170 days of incubation, soil samples were collected for analysis to evaluate soil attributes. U. brizantha was then planted to assess the efficiency of basalt powder, which was harvested at 40 days after sowing (first cut) and 70 days after sowing (second cut). The accumulation of nutrients and shoot dry mass (SDM) production were subsequently measured. The findings revealed that applying the highest dose of basalt powder (96 Mg ha−1) substantially elevated pH, and increased concentrations of phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+), copper (Cu), boron (B), and silicon (Si) in Oxisol (OX), while decreasing aluminum (Al3+) contents in the same soil. Furthermore, an average increase in the SDM of both U. brizantha harvests was observed, with a 6% increase in TQ and a 27% increase in OX. Additionally, an increase in the accumulation of P, K, Ca, Mg, and sulphur (S) in the shoot dry mass of the plants was observed with the basalt powder doses. These findings suggest that basalt powder has the potential to be an environmentally friendly alternative for soil fertilization, with positive impacts on soil chemical attributes and plant growth and nutrition.

Morphophysiological Aspects in African Mahogany (Khaya senegalensis) Seedlings Under Bovine Manure Doses

Objective: To evaluate the morphophysiological characteristics of Khaya senegalensis seedlings, after being grown in substrates with bovine manure. Theoretical framework: Based on scientific articles found on search engines and books in the field of physiology and forestry. This were the research used to support the explanation of how the physiological characteristics of the seedlings were influenced by the type of substrate and how they may have contributed to the morphological characteristics of these plants. Method: The experiment was conducted in a greenhouse for 90 days. During this period, the seedlings were subjected to doses of 0, 5, 10, 15, 20 and 25 grams of bovine manure. At the end, the net photosynthetic rate, transpiration rate, transpiration rate, vapor pressure deficit, stomatal conductance and intercellular CO2 concentration were evaluated. Then, height, diameter and biomass measurements were taken. Results and conclusion: The dose of 25 grams of bovine manure provided the best conditions when analysing the photosynthetic rate, stomatal conductance, intercellular CO2 concentration, vapor pressure deficit and transpiration rate. This resulted in greater growth in height and diameter, and greater production of aerial and root dry mass of K. senegalensis seedlings. Implications of the research: These results allow us to verify that, for seedlings to grow in a substrate containing bovine manure, first, improvements occur in the physiological conditions of the plants, which are reflected in faster growth. Therefore, there is a need to study the type of manure and the dose applied, before recommending a type of substrate. Originality/value: Use of organic waste for the seedlings production, which is an environmentally correct destination.

Agronomic potential of different fermented organic composts based on agro-industrial plant waste.

Organic composts such as "bokashi", obtained from the fermentation of bran mixtures and inoculated with microorganisms, improve soil characteristics. In Brazil, the most widely used formulation for the production of this compost is obtained from a mixture of wheat and castor bean bran, but both have a high monetary cost. Replacing these components with regionally available sources represents the possibility of reducing costs and making more sustainable use of this waste. The aim of this study was to analyze the chemical characteristics and determine the availability of nitrogen for the plants. The study was divided into two stages, consisting of an incubation test in the laboratory and a bioassay in the greenhouse using forage sorghum as an indicator species. In the laboratory trial, the treatments consisted of two raw material sources with a low C/N ratio (castor bean bran-CAB and cottonseed bran-COB), corresponding to 40% of the mixture; three sources with a high C/N ratio (wheat bran-WHB or rice bran-RIB), gradually replaced by passion fruit peel bran-PFPB), corresponding to 60% of the mixture. The materials were mixed, moistened, inoculated with microorganisms (Embiotic®) and kept in sealed containers with a capacity of 620 cm3 for 21days. In the greenhouse, in addition to the aforementioned treatments, seven controls were included: no addition of organic and synthetic N sources; ammonium nitrate; CAB; COB; WHB; RIB and PFPB. In the second stage, dry mass production and N content in sorghum plant tissues were determined, and the rates of N availability were estimated. It was found that the pH of the standard compost was 4.75, and in the other formulations it ranged from 4.62 to 5.3, the highest values being observed when WHB was fully replaced by RIB There was a significant difference in the EC values, but all were well below the value considered adequate. Replacing CAB with COB and WHB with RIB and PFPB resulted in a reduction in N content and an increase in the C:N ratio. Replacing WHB with PFPB led to an increase in K content and a reduction in P and Mg content. In the bioassay, the highest biomass production was in the treatments with the fermented composts, and the highest biological recovery of N was obtained in the ammonium nitrate treatment, followed by the CAB, COB and WHB treatments.

Doses of N in the Morphological and Physiological Characteristics of African Mahogany Seedling

Purpose: To analyse the growth of African mahogany (Khaya senegalensis) seedlings, regarding their morphology and physiology, in soil fertilized with different doses of N, from the application of ammonium sulphate. Theoretical framework: Based on scientific articles found on search engines and books in the area of ​​soil fertility and plant nutrition. To support the explanation of how the physiological characteristics of seedlings are related to the nutrition they receive from fertilization. Therefore, the application of different doses to the soil can provide different physiological responses, resulting in greater or lesser growth and dry mass production of plants. Method: The experiment was carried out in a completely randomized design with five doses of N and five replications, using ammonium sulphate as the source. The doses tested were: T0 – without fertilization; T1 – 50 mg dm-3; T2 – 100 mg dm-3; T3 – 150 mg dm-3; T4 – 200 mg dm-3. The seedlings were produced and then transplanted to the definitive container, when it received nitrogen fertilization. These seedlings went through an adaptation process and, at the end of 90 days, the morphological characteristics were evaluated: height, diameter, leaf dry mass, stem dry mass, root dry mass and; physiological characteristics: net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, vapor pressure deficit and transpiration rate. Results and conclusion: Nitrogen fertilization influenced the morphological and physiological characteristics of African mahogany seedlings. The greatest growth and production of dry mass was observed at doses of 100 and 150 mg dm-3 of N. These results were related to the increase in the net photosynthetic rate, stomatal conductance, transpiration and CO2 concentration. Recommending the most economical dose of 100 mg dm-3 of N. Research implications: These results indicate that nitrogen fertilization is essential for the quality growth of African mahogany seedlings, and the dose to be applied is essential for this to happen, since values ​​lower than this dose may not allow the plant to perform at its maximum. growth potential. Meanwhile, higher doses do not guarantee greater growth and will result in unnecessary expenses and, probably, loss of growth due to toxicity. Originality/value: Using nitrogen fertilizers, in the correct dose for the species, increases its growth potential and guarantees the production of quality seedlings within the nursery.

CARACTERÍSTICAS ESTRUTURAIS E PRODUTIVAS DO CAPIM MOMBAÇA SOB SOMBREAMENTO, NA FASE DE ESTABELECIMENTO

Forage grasses can be subjected to conditions that reduce the amount of light, either through intercropping with annual crops or through integration with tree species (silvopastoral system). Therefore, the objective of this work was to evaluate the productive and structural characteristics of grass. mombaça (Megathyrsus maximus), in the establishment phase, subjected to four levels of artificial shading (0, 30, 50 and 70%). The experimental design was completely randomized, with five replications. For this, plant height - PH, tiller length - TL, leaf/stem ratio (LSR), leaf dry mass, stem, dead and total material, tiller population density, individual tiller weight and number of leaves were evaluated. living and dead. Shading of 50% induced greater production of total dry mass (TDM), with no significant effect of TDM for the full sun and 30% treatments. A reduction in the number of tillers (NL) was observed as light was restricted, as well as an increase in plant height, tiller length and tiller dry weight. It is noteworthy that the highest average heights were found in 50 and 70% shading, as well as the highest individual tiller weights. The lowest production of total shoot dry mass and lowest LSR were found in the most severe shading. From the analysis of all variables, it can be inferred that mombaça grass presents better acclimatization in the range of 30 and 50% shading, which gives this cultivar good phenotypic plasticity, thus, the establishment of pasture is recommended in light to moderate shading. Therefore, the mombaça forage grass has potential for use in the silvopastoral system.

Selenium inorganic sources applied to soil: Effects on gas exchange and anatomical changes of radishes

Selenium (Se), in low doses, provides several beneficial effects, such as plant resistance to various abiotic stresses (e.g. drought stress and low/high temperatures). However, Se excess causes toxicity, with harmful impacts such as a decline in yield. Here, we studied the effects of fertilization with different Se sources and doses applied via soil on Se accumulation, toxicity, as well as on gas exchange, and anatomy of leaves and roots of radish plants. A randomized experimental design was adopted with three replications in a 2 × 3 + 1 factorial arrangement: two Se sources (sodium selenate – Na2SeO4 and sodium selenite – Na2SeO3·5H2O), three Se doses applied on soil (0.6, 1.2, and 1.8 mg dm−3), and one control treatment (without Se application). Each experimental unit consisted of one pot containing six radish plants. Selenate at 1.8 mg Se dm−3 increased the Se accumulation and radish dry matter. Selenite generally caused significant changes in the anatomical part, mainly in the conductive tissues of the leaves. In leaves with selenite fertilization, it was estimated that the maximum Se accumulation would be 5.9 µg plant−1 with a rate of 2.0 mg Se dm−3. However, it was impossible to estimate the maximum Se accumulation with selenate fertilization because as the dose increased, there were also increases in accumulation, thus presenting a linear regression. The maximum Se accumulation in radishes would be 10.7 µg Se plant −1 with 1.2 mg Se dm−3 by selenite and 45.8 µg Se plant−1 with 5.0 mg Se dm−3 by selenate. Although the highest dry mass production occurred with the 1.8 mg Se dm−3 through selenite, it is recommended to use smaller doses to provide adequate Se consumption selenate. The gas exchange and the anatomy of the plants changed due to Se fertilization through selenate and selenite.

Tolerância à salinidade e respostas espectrais foliares em mudas de quatro espécies ornamentais herbáceas

ABSTRACT Studies on using brackish water for the irrigation of ornamental species are still scarce, mainly considering qualitative aspects of the plants. Therefore, the present study aimed to identify salt tolerance and characterize leaf spectral responses of herbaceous ornamental species at the stage of commercial seedling production. The research was carried out from December 2020 to February 2021, under greenhouse conditions, in Fortaleza - Ceará, Brazil. The experiment was conducted in a randomized block design with split plots, with main plots consisting of irrigation-water salinity levels (0.5, 2.0, 4.0, 6.0, and 8.0 dS m-1), and subplots by the species Catharanthus roseus, Celosia cristata, Celosia plumosa, and Chrysanthemum coronarium, with four replications. The evaluation parameters were dry mass production, visual sensory analysis, salt tolerance, and leaf spectral responses. Plant visual quality was maintained up to 2.0 dS m-1 for Chrysanthemum coronarium and 4.0 dS m-1 for Celosia cristata, Celosia plumosa, and Catharanthus roseus, which were classified as moderately tolerant at those respective salinity levels. Salinity caused noticeable changes in leaf spectral responses, especially in the visible region.

Использование алгоритма оптимизации DIRECT и кусочно-линейных функций для построения нелинейных регрессионных моделей по гетероскедастичным данным

Nonlinear regression models are an important tool in agricultural research, as many biological processes are theoretically and experimentally described by nonlinear functions. In addition to accurately describing experimental data, nonlinear models have the property of physical interpretability of parameters and are more robust outside the domain of the studied sample. Currently, existing methods for calculating model coefficients – such as Ordinary Least Squares, Weighted Least Squares, and Generalized Least Squares – have several drawbacks. The most advanced Generalized Least Squares method relies on a large number of axioms, which are often not adhered to in real examples, and the theoretical proof is not apodictic. This article introduces a flexible, robust, and accurate method for calculating coefficients for arbitrary single-factor regression models based on the maximum likelihood estimation method. The method is theoretically justified with a minimal number of axioms, and examples of results from the software implementation are provided for the logistic function and the Michaelis function using synthetic test data and experimental samples of dry grass mass production depending on the volume of nitrogen fertilizers. The main advantage of the method lies in the simplicity of theoretical proof and the small number of theoretical constraints on the input parameters of the problem. Unlike Generalized Least Squares, the proposed method deterministically converges to the absolute minimum, thanks to the use of the DIRECT algorithm. It can account for heteroscedasticity and does not require manual tuning of optimization parameters to ensure convergence. Considerations for possible extensions of the method to multifactorial regression analysis and potential improvements for heteroscedasticity estimation are also presented.

NITROGEN IMPROVES BIOMASS PRODUCTION AND CHLOROPHYLL SYNTHESIS IN BASIL PLANTS GROWN UNDER SALT STRESS

Basil (Ocimum basilicum L.), a medicinal and aromatic plant extensively cultivated in the Northeast region of Brazil, encounters growth challenges attributed to the salinity of irrigation water and soil. Nitrogen (N) is a crucial macronutrient employed to mitigate salt stress in plants. Therefore, this study aimed to evaluate the production of phytomass and chlorophyll synthesis in purple basil plants grown under salinity stress and nitrogen fertilization. The experiment was conducted in 2021 under protected environmental conditions at the Center for Agricultural Sciences, Universidade Federal Paraíba, Areia-PB, Brazil. Five levels of salt stress (0.0, 0.80, 2.75, 4.70, and 5.50 dS m-1) and five doses of N (0.00, 58.58, 200.00, 341.42, and 400.00 mg L-1) applied via foliar were studied. The results revealed that foliar fertilization with N increases plant tolerance to salt stress, promoting root fresh and dry mass accumulation at 294.96 and 205.36 mg L-1 and under ECw of 1.14 and 0.5 dS m-1, respectively. Applying 217.39 and 231.30 mg L-1 of N improves the production of stem dry biomass and the shoot/root ratio of basil plants subjected to salinity of 0.5 dS m-1. The electrical conductivity of irrigation water above 0.8 dS m-1 adversely affects biomass production. The salinity at 3.8 to 4.0 dS m-1 stimulated chlorophyll synthesis in purple basil plants. However, the foliar application of N proves to be a strategic approach to counteract these effects, resulting in increased total dry mass production and chlorophyll contents.

Substrates based on carbonized rice husk combined with phosphate fertilization in coriander and mustard seedlings

Combinations of substrates of easy acquisition and nutrients availability favor the production of quality seedlings with lower production cost. Aiming at an alternative for the production of quality seedlings from the insertion of low-cost, sustainable raw material into the commercial substrate, the present work aimed to evaluate the effect of different proportions of the composition of the carbonized rice husk mixture, sand and soil (3:1:3 V:V:V) with commercial substrate (composed of peat fiber and vermiculite), with or without added phosphorus, without development of coriander and mustard seedlings. The experiment was executed in a greenhouse under a randomized block design with six seedlings per plot and seven replications. The treatments were arranged in a 5x2 factorial scheme with 0, 25, 50, 75 and 100 % of the combination added to the commercial substrate with or without addition of triple superphosphate. After 35 days of emergency, plant height, shot dry mass production and roots dry mass production were evaluated. The results showed that there was no effect on the phosphate fertilizer addition to the substrates tested in any evaluated trait, as well as significant interaction between the factors studied in the development of seedlings. The height and dry matter yield of shoots and roots were higher when the combination of carbonized rice husk, sand and soil was added to the commercial substrate in proportions of 50 % and 75 % and 100 % in both vegetables. Carbonized rice husk proved to be an efficient alternative substrate for the production of coriander and mustard seedlings.

Initial Growth of Red Tent Seedlings (Adenanthera Pavonina l.) In Soil Enriched with Different Doses and Nitrogenous Sources

Purpose: To evaluate the initial growth of red tent seedlings in different doses and sources of N. Theoretical framework: Based on scientific articles found on search engines and books in the area of soil fertility and plant nutrition. This is to support the explanation of how the morphological characteristics of seedlings, which explain their growth, are affected by nitrogen fertilization, depending on the dose and source of fertilizer applied. Method: The experiment was carried out in a completely randomized design with five doses of N and five replications, using urea and ammonium sulfate as sources, which were evaluated separately. The doses tested were: T0 – without addition of N; T1 – 50 mg dm-3; T2 – 100 mg dm-3; T3 – 150 mg dm-3; T4 – 200 mg dm-3, for each source tested. At the end of 90 days, the morphological characteristics of the seedlings were evaluated: height, diameter, height/diameter ratio, dry mass of the aerial part, dry mass of the root part, aerial dry mass/root dry mass ratio, height/aerial dry mass ratio and, Dickson quality index. Results and conclusion: Growth, dry mass production and seedling quality were greater at a dose of 200 mg dm-3 when using urea as a source of N. When the source was ammonium sulfate, the greatest growth in height occurred at a dose of 100 mg dm-3, however, the greatest growth in diameter, the greatest production of dry mass and quality, were observed at a dose of 200 mg dm-3. This is the recommended dose for the species studied. Research implications: These results indicate that nitrogen fertilization is essential for the quality growth of red seedlings, and the dose to be applied is essential for this to happen, since values lower than this dose may not allow the plant to perform at its maximum. growth potential. Meanwhile, higher doses do not guarantee greater growth and will result in unnecessary expenses and, probably, loss of growth due to toxicity. Originality/value: Using nitrogen fertilizers, in the correct dose for the species, increases its growth potential and guarantees the production of quality seedlings within the nursery.

IMPACTS OF WATER STRESS ON Urochloa brizantha FORAGE CULTIVARS

Water deficit during the dry season is one of the main factors affecting the productivity and quality of pastures. The present work aims at evaluating the effects of water deficit on the morphological and productive characteristics of Urochloa brizantha cultivars grown in Quartzarenic Neosol. The experiment was conducted in a greenhouse under a completely randomized design with a 4×2 factorial arrangement, with four cultivars (Marandu, MG4, MG13 Braúna and MG5 Vitória), two water availability conditions (50% or 100% of field capacity) and six repetitions. Structural, morphogenic and productive variables were evaluated 15, 25 and 35 days after the beginning of treatment application. For all productive characteristics evaluated during 35 days of water stress, it was observed that a 50% reduction in water availability significantly (P<0.05) reduced total fresh and dry mass production and leaf production of Marandu, MG13 Braúna and MG5 Vitória. Except for MG13 Braúna, the leaf/stem ratio of these cultivars was impaired. Regardless of water availability, when comparing forages during 35 days, lower cumulative leaf length and higher fresh and dry mass production of stems were observed in the Marandu cultivar. Regarding the response of productive characteristics, the MG4 cultivar showed the best results under water deficit when grown in Quartzarenic Neosol.

Sunflower root growth and distribution under varied water regimes in two edaphoclimatic conditions

Sunflower growth is adversely impacted by both excess and insufficient water. Research on root growth in this crop under water stress conditions remains limited and does not fully elucidate the plant's response to varying soil and climatic conditions. This study aimed to determine root growth, depth, and distribution of sunflower plants under different water stress conditions, such as deficit or excess, in two soil classes and sown during two distinct periods. Experiments were conducted after sowing at the beginning of September (first crop season) and at the beginning of January (second crop season) in an Ultisol (Santa Maria, Rio Grande do Sul State, Brazil) and an Oxisol (Panambi, Rio Grande do Sul State, Brazil). Water condition treatments applied from stage V6 included control, water deficit, and water excess. Roots were collected using an auger drill during the first crop season. The variables analyzed comprised root length density and accumulated root within the soil profile. During the second crop season, sunflower roots were visually assessed in the soil profile after trench excavation. Root system depth and root dry mass were evaluated during both sowing periods. Results indicated that sunflower root penetration is deeper in Ultisol than in Oxisol. Water deficit promotes root depth, while water excess promotes root growth near the surface. Sowing during the first crop season results in deeper root penetration and higher root dry mass production compared to the second crop season.

Nickel sources affect soil biological properties but do not affect sorghum growth

Nickel (Ni) is an essential element, but it can be phytotoxic in high concentration, which may be caused by high availability in soil solution. The objective of this study was to evaluate the effect of sources and doses of Ni applied to a dystrophic Red Latosol cultivated with sorghum on i) the availability of the metal in the soil; ii) the impact on biological and biochemical properties of the soil; iii) the absorption and distribution in sorghum plants; and iv) crop productivity. The experiment was carried out within a completely randomized design with two nickel sources [nickel(II) nitrate, Ni(NO3)2 and nickel(III) oxide, Ni2O3], three doses (35, 70, and 140 mg Ni kg−1 soil), plus controls without Ni, with 3 replications. The concentrations of Ni in the soil, soil microbial biomass (SMB), basal soil respiration (BSR), metabolic quotient (qCO2), fluorescein diacetate (FDA) hydrolysis, and urease activity were determined. The concentrations of Ni in the leaf diagnostic and in the plant (shoot, root, and grains) were also measured. In the soil, the concentrations of available Ni remained between 0.21 and 54.01 mg Ni kg−1. Ni2O3 contributed very little to the increase in available Ni. SMB and the FDA hydrolysis were not affected by the Ni source or Ni dose, but BSR and qCO2 had significant increase with Ni application rates, suggesting the soil microorganisms faced stress. Soil urease activity was affected by Ni dose but not by Ni source. The dose of Ni as Ni(NO3)2 decreased the metal concentration in the plant, while that of Ni2O3 increased it. Nickel source did not affect dry mass production of the plants, but grain yield was affected in a dose-dependent manner when Ni2O3 was the source of Ni.

Morphological and Physiological Characteristics os African Mahogany (Khaya Senegalensis) Seedlings in Substrate with Poultry Manure

Purpose: Evaluate the morphophysiological characteristics of Khaya senegalensis seedlings, after being cultivated in substrates with poultry manure. Method/design/approach: The experiment was conducted in a greenhouse for 90 days. During this period, the seedlings were subjected to doses of 0, 5, 10, 15, 20 and 25 grams of poultry manure. At the end, they were evaluated for net photosynthetic rate, transpiration rate, transpiration rate, vapor pressure deficit, stomatal conductance and intercellular CO2 concentration. Then, measurements of height, diameter and biomass were performed. Results and conclusion: The dose of 25 grams provided the best conditions when analysing the physiological characteristics, which resulted in greater growth and greater dry mass production of K. senegalensis seedlings. Research implications: These results show that, for the seedlings to grow in a substrate containing poultry manure, firstly, there are improvements in the physiological conditions of the plants, which are reflected in faster growth. Therefore, there is a need to study the type of manure and the dose that is applied, before recommending a type of substrate. Originality/value: Use of organic waste for seedlings production, which is an environmentally correct destination.