Artigos - Produção e Melhoramento Vegetal - FCA

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  • ItemArtigo
    Lasting effect of Urochloa brizantha on a common bean-wheat-maize rotation in a medium-term no-till system
    (2023-01-01) Crusciol, Carlos Alexandre Costa [UNESP]; Santos Ferreira, João Henrique [UNESP]; Momesso, Letusa [UNESP]; Portugal, José Roberto [UNESP]; de Campos, Murilo [UNESP]; Volf, Marcelo Raphael; Borghi, Emerson; Soratto, Rogério Peres [UNESP]; Calonego, Juliano Carlos [UNESP]; Universidade Estadual Paulista (UNESP); São Paulo Western University (UNOEST); Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
    Grass intercropping under no-till is an option to increase crop residues on the soil surface and crop diversity. Urochloa spp. is frequently selected for intercropping to improve land use and agricultural production because of its high residue production, slow residue decomposition, as well as its vigorous, abundant, and deep root system. However, the effects of intercropping Urochloa and maize, especially the effects of Urochloa residues, on subsequent crops in rotation have not been established. To address this knowledge gap, a field experiment was carried out over 5 years (from 2014 to 2018) comprising 2 years of maize monocropping or intercropping and 3 years of crop rotation (common bean-wheat-common bean-wheat-maize). We evaluated the medium-term effects of monocropped maize or maize intercropped with Urochloa brizantha on soil fertility and the development, yields, and grain nutrient accumulation of subsequent common bean, wheat, and maize crops. The cultivation of U. brizantha in the intercropping system improved soil fertility over at least 4 years, with increases in soil pH; soil organic matter (SOM); phosphorus (P); exchangeable potassium (K), calcium (Ca), and magnesium (Mg); sulfur (S–SO42−); cation exchange capacity (CEC); and base saturation (BS) at all soil depths. The benefits of U. brizantha extended to root dry matter and distribution; 70–77% of the total roots were concentrated within a soil depth of 0.0–0.2 m. The intercropping system improved the root dry matter mass, yield components, and grain yields of subsequent common bean, wheat, and maize crops in all cultivation years. These findings indicate that intercropping maize and U. brizantha provides medium-term benefits for subsequent common bean, wheat, and maize crops, and improves nutrient cycling to increase soil P; exchangeable K, Ca, and Mg; S–SO42−; and organic matter content.
  • ItemArtigo
    Effect of ripeners on the nutrient concentrations of sugarcane leaves
    (2023-01-01) Silva, Marcelo de Almeida [UNESP]; Santos, Hariane Luiz [UNESP]; Germino, Gabriel Henrique [UNESP]; Véliz, José Gerardo Espinoza; Universidade Estadual Paulista (UNESP); Centro Guatemalteco de Investigación y Capacitación de la Caña de Azúcar (CENGICAÑA)
    Using chemical ripeners in the sugarcane favors the increase of sucrose productivity, regulates the effects of adverse weather conditions for ripening, and promotes the anticipation of harvest. However, it can also modify the nutrient absorption, translocation, and accumulation process and, consequently, affect the nutrient cycling of the straw maintained on the soil surface. Thus, this research aimed to evaluate ripeners’ effects (glyphosate − 0.5 L ha−1; sulfometuron-methyl − 0.02 kg ha−1, and trinexapac-ethyl − 0.8 L ha−1) on the nutritional status of the sugarcane leaf canopy. Natural ripening maintained the highest levels of P and Zn throughout the time. The highest levels of N, P, and K were provided by trinexapac-ethyl in most of the evaluated periods, as well as contributing to the highest levels of Ca, Mg, and S, along with sulfometuron methyl, from 30 to 60 days after application (DAA). The highest levels of B and Zn were observed under sulfometuron methyl. On the other hand, glyphosate was the ripener responsible for the lowest nutrient concentrations in the leaf canopy, including N, Ca, Mg, and S at 45 DAA and B and Mn at 30 and 45 DAA. Considering the importance of maintaining the straw for nutrient cycling, in addition to being a ripener, trinexapac-ethyl contributed to the maintenance of high levels of nutrients in the leaf canopy in relation to the other ripeners, which suggests a greater possibility of availability of these nutrients for the ratoon development in the upcoming cycles.
  • ItemArtigo
    Morphoanatomical characterization to differentiate two biotypes of Paspalum virgatum
    (2023-01-01) Vasco, Alana Nascimento; Marques, Ricardo Fagundes [UNESP]; Justo, Cristina Filomena; Martins, Dagoberto [UNESP]; de Marchi, Sidnei Roberto; Universidade Federal de Mato Grosso; Universidade Estadual Paulista (UNESP)
    The species Paspalum virgatum L. is considered to be a pasture weed that causes great damage to livestock. There are two empirically identified biotypes that differ in leaf blade width. Thus, the objective of this work was to differentiate two biotypes of P. virgatum based on the main aspects of leaf morphology and anatomy. Morphological characterization used the leaves of the third node of each biotype with five replications for both of them. For anatomical characterization, the median part of the leaf of the third node was collected. The evaluations consisted in the main leaf morphoanatomical parameters. The biotypes differ in leaf area, leaf blade width, sheath length and diameter, and inflorescence and canopy height. The “narrow” leaf biotype showed lower stomatal density on both sides of the blade. Therefore, leaf blade width is valid as the basis for empirical observation of the difference between biotypes.
  • ItemArtigo
    Physiological Quality of Soybean Seeds as a Function of Soil Management Systems and Pre-Harvest Desiccation
    (2023-03-01) Silva, Gustavo Ferreira da [UNESP]; Chamma, Larissa [UNESP]; Luperini, Bruno Cesar Ottoboni [UNESP]; Chaves, Prínscilla Pâmela Nunes [UNESP]; Calonego, Juliano Carlos [UNESP]; Nakagawa, João [UNESP]; Silva, Edvaldo Aparecido Amaral da [UNESP]; Universidade Estadual Paulista (UNESP)
    Soil management systems directly interfere in the soil–plant relationship. However, there are still few studies evaluating the influence of long-term management systems on the physiological quality of soybean seeds. Another little-known topic is the influence of pre-harvest desiccation on the physiological quality of soybean seeds, especially on seed longevity. Thus, the aim of this research was to evaluate the physiological quality of soybean seeds cultivated under conventional tillage and no-tillage systems with and without desiccant use. The experiment was carried out in design is a split plot in a randomized complete block design. The treatments consisted of soil management systems (conventional tillage and no-tillage), with and without pre-harvest desiccation. In the treatment with desiccation, the herbicide Paraquat was applied, when the plants were at the R7.3 phenological stage (most of the seeds had a yellowish coat, with a shiny surface and were already detached from the pod). Seed germination, vigor (first germination count, seedling dry mass, seedling length, time to reach 50% germination (T50), seedling emergence and emergence speed index) and longevity (P50) were evaluated. Seeds cultivated under conventional tillage showed greater vigor for most traits evaluated, with values of T50 and seedling length higher by 24.39% and 24.77%, respectively, compared to NT. In addition, non-desiccation increased the seedling length and dry mass, in 15.45% and 21.59%, respectively. The use of desiccant aiming at seed vigor is dependent on the soil management system. Soybean seed longevity was superior in the no-tillage system, but desiccant application reduced seed longevity.
  • ItemArtigo
    Mean-weight diameter of aggregation as affected by initial screen size of two fine-textured soils
    (2023-05-01) Franzluebbers, Alan J.; Tanaka, Katiuça Sueko [UNESP]; Momesso, Letusa [UNESP]; Calonego, Juliano Carlos [UNESP]; Crusciol, Carlos Alexandre Costa [UNESP]; USDA Agricultural Research Service; Universidade Estadual Paulista (UNESP)
    Soil aggregation is considered a key indicator of soil health to protect soil against erosion, enhance organic C storage, and offer habitat for soil organisms. Various methods to assess aggregation may change interpretations of management, and therefore should be cross-calibrated. We assessed the impact of initial sieve opening size (8 or 4.75 mm) prior to determination of dry-stable and water-stable mean-weight diameter (MWD) from two fine-textured soils—a Rhodic Hapludox from São Paulo, Brazil and a Rhodic Kanhapludult from North Carolina, United States. Both soils were subjected to management expected to alter surface soil conditions. As expected, initial sieving through 8 mm led to greater dry-stable MWD (3.37 ± 0.60 mm) than initial sieving through 4.75 mm (1.94 ± 0.28 mm). However, soil stability index (water-stable MWD/dry-stable MWD) was not affected by initial sieve size opening (0.56 ± 0.13 mm mm−1 under both initial sieve openings). Management interpretations were consistent with both approaches as well, and in particular to detect the strong depth effect on water-stable MWD (i.e., declining with depth). Water-stable macroaggregates had 32% ± 25% greater C concentration than microaggregates; similarly under both initial sieving conditions. Soil stability index when initially sieved through 4.75 mm was highly associated with aggregate stability of 1–2-mm sized dry aggregates, which is a more common procedure. We conclude that passing soil through a screen with 4.75-mm openings to conduct a diversity of soil analyses can be appropriate for obtaining reasonable estimates of and interpretations about surface soil aggregation.
  • ItemArtigo
    Adjusting peanut plant density and potassium fertilization for different production environments
    (2023-03-01) Cordeiro, Carlos Felipe dos Santos [UNESP]; Pilon, Cristiane; Echer, Fábio Rafael; Albas, Renato; Tubbs, R. Scott; Harris, Glendon H.; Rosolem, Ciro Antonio [UNESP]; Universidade Estadual Paulista (UNESP); University of Georgia; Raposo Tavares HWY
    Peanut pod yield and its response to fertilizer-K can be affected by the environment × plant density interaction. Research was conducted with the objective of determining peanut growth and yield response to planting density and fertilizer-K application under rainfed conditions in Brazil and irrigation in the United States. The effects of plant planting density and K fertilization were more frequent in rainfed areas, compared to irrigated environments. Peanut leaf area index (LAI) and dry matter accumulation (DM) increased with increasing plant density (mainly at 30 days after plant emergence—average increments of 70% and 80% for LAI and DM, respectively), whereas the stomatal conductance was decreased, mainly in rainfed fields. In low-K soil, the application of 50 kg ha−1 of K increased leaf K concentration (12% [Brazil], first-year area and 28% crop rotation area) and stomatal conductance in rainfed fields, resulting in greater yield (23% [1340 kg ha−1; Brazil], first-year area) at low plant density. In the irrigated fields, yield increased with plant densities up to 19 plants m−2. For rainfed crops, plant density exceeding 11 plants m−2 resulted in lower yield in the area of adequate K content in the soil. Therefore, in rainfed fields, plant density must be low to assure peanuts response to K. In irrigated environments, high plant density is less detrimental to peanut yield, but no increase is observed with plant density greater than 19 plants m−2. Additionally, there was no yield increase with the application of 50 kg ha−1 of K, in irrigated environments.
  • ItemArtigo
    Inoculation with Azospirillum brasilense as a strategy to enhance sugarcane biomass production and bioenergy potential
    (2023-03-01) Scudeletti, Daniele [UNESP]; Crusciol, Carlos Alexandre Costa [UNESP]; Momesso, Letusa [UNESP]; Bossolani, João William [UNESP]; Moretti, Luiz Gustavo [UNESP]; De Oliveira, Elisa Fidêncio [UNESP]; Tubaña, Brenda Servaz; Silva, Marcelo de Almeida [UNESP]; de Castro, Sérgio Gustavo Quassi; Hungria, Mariangela; Universidade Estadual Paulista (UNESP); LSU AgCenter; AgroQuatro-S applied agronomic experimentation; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
    Azospirillum inoculation has gained wide prominence as a strategy for fostering both increased sustainability and enhanced agricultural productivity. Plant growth-promoting bacteria such as Azospirillum improve resource use by plants, but proper management of Azospirillum inoculant application in sugarcane (Saccharum spp.) is key to achieving crop yield potential and improving product quality and economic return for farmers. The present study evaluated the application of different doses of A. brasilense inoculant [0, 5, 10, 15 or 20 × 1010 colony forming units (CFU) ha−1] to sugarcane at the setts/sprouting and tillering stages in two crop seasons at two sites under field conditions. The experiment comprised plant cane and first ratoon at Site A and first and second ratoons at Site B. No effects of inoculation on crop nutrition or the technological quality of the raw material were observed. However, the effects of the inoculation on the biometric parameters and yield of sugarcane varied with the dose. The two highest A. brasilense doses (15 and 20 × 1010 CFU ha−1) increased the stalk population and stalk yield of both plant cane and ratoon sugarcane by approximately 2 stalks m−1 and 20 Mg ha−1, respectively. In addition, the two highest inoculation doses promoted increases in sugar and energy production that were consistent with the increase in stalk population and stalk yield. No clear pattern of the effects of inoculant application time on sugarcane was observed. Overall, A. brasilense inoculation promoted sugarcane productivity when applied at high inoculation doses at the sprouting and tillering stages and has the potential to maximize agronomic and economic benefits to the sugarcane sector.
  • ItemArtigo
    Calcium and Boron Fertilization Improves Soybean Photosynthetic Efficiency and Grain Yield
    (2022-11-01) Galeriani, Tatiani Mayara [UNESP]; Neves, Gabriel Oliveira [UNESP]; Santos Ferreira, João Henrique [UNESP]; Oliveira, Rafael Neres [UNESP]; Oliveira, Sirlene Lopes [UNESP]; Calonego, Juliano Carlos [UNESP]; Crusciol, Carlos Alexandre Costa [UNESP]; Universidade Estadual Paulista (UNESP)
    Foliar fertilization with calcium (Ca) and boron (B) at flowering can promote flower retention and pod fixation, thereby increasing the number of pods per plant and, in turn, crop productivity. The objective of this work was to investigate the effects of Ca + B fertilization during flowering on the nutritional, metabolic and yield performance of soybean (Glycine max L.) The treatments consisted of the presence and the absence of Ca + B fertilization in two growing seasons. Crop nutritional status, gas exchange parameters, photosynthetic enzyme activity (Rubisco), total soluble sugar content, total leaf protein concentration, agronomic parameters, and grain yield were evaluated. Foliar Ca + B fertilization increased water use efficiency and carboxylation efficiency, and the improvement in photosynthesis led to higher leaf sugar and protein concentrations. The improvement in metabolic activity promoted a greater number of pods and grains plant−1, culminating in higher yields. These results indicate that foliar fertilization with Ca + B can efficiently improve carbon metabolism, resulting in better yields in soybean.
  • ItemArtigo
    Sugarcane Productivity as a Function of Zinc Dose and Application Method
    (2022-11-01) Silva, Marcelo de Almeida [UNESP]; Germino, Gabriel Henrique [UNESP]; de Holanda, Lucas Almeida; Oliveira, Laura Costa [UNESP]; Santos, Hariane Luiz [UNESP]; Sartori, Maria Márcia Pereira [UNESP]; Universidade Estadual Paulista (UNESP); and Technology of Mato Grosso (IFMT)
    Sugarcane is one of the main crops in Brazilian agriculture. It has high economic and productive potential, but its current productivity is still lacking due to poor nutritional management in both the soil and the plant. Zinc (Zn) directly affects tillering and plant growth, which are critical factors to sugarcane productivity and ratoon longevity. Thus, this research aimed to evaluate the effects of Zn chelate doses (185, 260, and 330 g ha−1) and two application methods (furrow and foliar applications) on the tillering, yield, and quality of sugarcane. The Zn chelate fertilization via furrow at a dose of 330 kg ha−1 provided increases of 13.59%, 17.6%, and 17.0% in stalk height (SH), stalk (TSH) productivity, and sugar (TPH) productivity, respectively. In contrast, Zn foliar application at a dose of 260 g ha−1 provided increases of 3.71%, 20.7%, and 17.0% in SH, TSH, and TPH, respectively. The optimal Zn chelate fertilization in sugarcane cultivation can be performed at a dose of 330 g ha−1 via furrow application at planting or at a dose of 260 g ha−1 via foliar application 145 days after planting.
  • ItemArtigo
    Dynamics of 2,4-D and Dicamba Applied to Corn Straw and Their Residual Action in Weeds
    (2022-10-01) Gazola, Tiago [UNESP]; Costa, Renato Nunes [UNESP]; Carbonari, Caio Antonio [UNESP]; Velini, Edivaldo Domingues [UNESP]; Universidade Estadual Paulista (UNESP)
    2,4-D and dicamba are used in the postemergence management of eudicotyledonous weeds in different crops, most of which are grown under no-tillage systems. Due to the application methods for these products, their dynamics in straw and their residual action in soil have rarely been explored. Thus, the objective of this study was to evaluate the dynamics of 2,4-D and dicamba that have been applied to corn straw and to verify their relationship with residual control action in weeds. In the dynamics experiments, the herbicides were applied to 5 t ha−1 of straw, and rainfall simulations were performed with variable amounts and at different periods after application to evaluate herbicide movement in the straw. In the residual action experiments, the species Digitaria insularis, Conyza spp., Bidens pilosa, Amaranthus hybridus, Euphorbia heterophylla, and Eleusine indica were sown in trays, and 2,4-D and dicamba were applied directly to the soil, to the soil with the subsequent addition of the straw, and to the straw; all of these applications were followed by a simulation of 10 mm of rain. The physical effect of the straw and the efficacy of the herbicides in terms of pre-emergence control of the weed species were evaluated. The leaching of 2,4-D and dicamba from the corn straw increased with a higher volume of rainfall, and the longer the drought period was, the lower the final amount of herbicide that leached. The presence of the corn straw on the soil exerted a physical control effect on Conyza spp.; significantly reduced the infestation of D. insularis, B. pilosa, A. hybridus, and E. indica; and broadened the control spectrum of 2,4-D and dicamba, assisting in its residual action and ensuring high levels of control of the evaluated weeds. In the absence of the straw, 2,4-D effectively controlled the pre-emergence of D. insularis, Conyza spp., and A. hybridus, and dicamba effectively controlled D. insularis, Conyza spp., B. pilosa, A. hybridus, E. heterophylla, and E. indica.
  • ItemArtigo
    Soil–Plant Relationships in Soybean Cultivated under Crop Rotation after 17 Years of No-Tillage and Occasional Chiseling
    (2022-10-01) Silva, Gustavo Ferreira da [UNESP]; Matusevicius, Ana Paula Oliveira [UNESP]; Calonego, Juliano Carlos [UNESP]; Chamma, Larissa [UNESP]; Luperini, Bruno Cesar Ottoboni [UNESP]; Alves, Michely da Silva [UNESP]; Leite, Hugo Mota Ferreira; Pinto, Elizabete de Jesus; Silva, Marcelo de Almeida [UNESP]; Putti, Fernando Ferrari [UNESP]; Universidade Estadual Paulista (UNESP); Federal University of Acre (UFAC); University of Recôncavo of Bahia (UFRB)
    No-tillage cover crops contribute to better soil quality, being able to replace mechanized tillage management. This observation can only be made after several years of adopting conservationist practices and through research on soil–plant relationships. The objective of the research was to verify the relationship between the production components, physiological, root development, and physical-hydric properties of the soil in the yield of soybean grown in succession to different cover crops or with soil chiseling. The experiment was carried out in a randomized block design with four replications, comparing the cultivation of sunn hemp (Crotalaria juncea) and millet (Penninsetum glaucum L.) as cover crops and a treatment with soil chiseling. The evaluations were carried out during soybean (Glycine max L.) cultivation in the 2019/20 summer crop, that is, after 17 years of experimenting started in 2003. Rotation with sunn hemp increased soybean yield by 6% and 10%, compared with millet rotation and soil chiseling. The species used in crop rotation in a long-term no-tillage system interfere with the physical and water characteristics of the soil, affecting the physiological responses and soybean yield. The rotation with sunn hemp offers greater water stability to the plants and provides greater soybean yield in succession. Future research that better addresses year-to-year variation, architecture, and continuity of pores provided by crop rotation, and evaluations of gas exchange, fluorescence, and activities of stress enzymes in soybean plants may contribute to a better understanding of soil–plant relationships in long-term no-till.
  • ItemArtigo
    Dynamics and weed control effectiveness of dicamba herbicide when applied directly on the soil and corn straw in Brazil
    (2022-01-01) Mundt, Tamara Thaís [UNESP]; Carbonari, Caio Antonio [UNESP]; Moisinho, Ivana Santos [UNESP]; de Brito, Ivana Paula Ferraz Santos [UNESP]; Picoli Junior, Gilmar José; Ovejero, Ramiro Fernando Lopez; Velini, Edivaldo Domingues [UNESP]; Universidade Estadual Paulista (UNESP); Bayer CropScience
    Dicamba is a post-emergence herbicide commonly used to control broadleaves in cereal crops. However, a portion of the herbicide might reach soil surface, and many factors could affect its dynamics and effects. The objective of this research was to evaluate the dynamics of dicamba applied to the soil, to the soil and covered with straw and over the straw, in addition, to evaluate the weed control in pre-emergence. Two field experiments at different locations were conducted with dicamba. To quantify dicamba in the soil a LC-MS/MS system was used. In both experiments, rainfall and straw played a key role in dicamba soil dynamics and weed control. Dicamba in the soil was affected by presence of straw and accumulated rainfall after the application. Higher concentrations (254–432 ng g soil−1) in the soil 0–10 cm layers and greater leaching potential were found for the application in the soil compared to over the straw. The maximum concentration of dicamba (101.6–226 ng g soil−1) was found after 10 mm of rainfall for dicamba application over the straw. Around 60–70% of weeds were controlled with concentrations greater than 20 ng/g soil−1, in the presence or absence of straw.
  • ItemArtigo
    Common Bean Plant Size and Yield in Response to Rates of Foliar-Applied Paclobutrazol, Mepiquat Chloride, and Prohexadione Calcium
    (2023-06-01) de Oliveira, Luan Santos; Soratto, Rogério Peres [UNESP]; Cairo, Paulo Araquém Ramos; da Silva, Leandro Dias; Matsumoto, Sylvana Naomi; Silva, Ricardo de Andrade; State University of Sowthwestern Bahia (UESB); Universidade Estadual Paulista (UNESP); University Center Arnaldo Horácio Ferreira (UNIFAAHF)
    Growth retardants have been used as an anti-lodging to reduce shoot growth by blocking the gibberellins biosynthesis without decreasing yield. We hypothesized that the type and dosage of growth retardants vary in effectiveness on reducing vegetative growth and increasing seed yield, as well as that prohexadione calcium (Pro-Ca) may also be an effective growth retardant for common bean (Phaseolus vulgaris L.). The goal of this study was to assess the effects of increasing rates of paclobutrazol (PBZ), mepiquat chloride (MC), and Pro-Ca on common bean morphophysiological and yield traits, based on a field experiment carried out in Vitória da Conquista, northeastern Brazil. Morphophysiological traits were assessed 14 and 38 days after application (DAA) of regulators, and yield traits were assessed at the end of the crop cycle. There was a positive relationship between increasing rates of regulators and decrease in stem length mainly up to 14 DAA, and Pro-Ca was more effective than the other regulators. At 38 DAA, increase in shoot dry mass was recorded when PBZ and MC were sprayed at rates from 100 to 400 g a.i. ha−1. Pro-Ca application increased the height of first pod insertion. Low rates of PBZ (25–50 g a.i. ha−1) increased, whereas high rates of Pro-Ca (200 and 400 g a.i. ha−1) tended to decrease the number of pods per plant. MC reduced the number of empty pods and increased the number of seeds per pod. The 100-seed weight increased up to a peak with an estimated rate of 162.5 g a.i. ha−1 for PBZ, 151.0 g a.i. ha−1 for MC, and 211.8 g a.i. ha−1 for Pro-Ca. PBZ and MC marginally increased seed yield with peaks at the estimated rates of 190.8 and 212.4 g a.i. ha−1, respectively, whereas rates of Pro-Ca greater than 50 g a.i. ha−1 decreased seed yield. The regulators were effective in reducing the plant size, thus mitigating lodging risks in common bean crop with highlight on Pro-Ca, but this regulator at high rates tended to reduce common bean yield.
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    SOWING DEPTH AND LIGHT INTENSITY IN THE EMERGENCE AND DEVELOPMENT OF MONOCOTYLEDONOUS WEEDS
    (2022-02-16) Marques, Ricardo Fagundes [UNESP]; Souza, Guilherme Sasso Ferreira [UNESP]; Pereira, Maria Renata Rocha; Marchi, Sidnei Roberto; Martins, Cibele Chalita [UNESP]; Martins, Dagoberto [UNESP]; Universidade Estadual Paulista (UNESP); Technology College of the State of São Paulo-Capão Bonito; State University of Mato Grosso
    This study aimed to evaluate the effects of different sowing depths and light intensities on the emergence and development of the monocot weed species, Urochloa decumbens and Cenchrus echinatus, under field conditions. Each species constituted an experiment, and the experimental design was completely randomized with four replicates. The treatments were arranged in a 6 x 4 factorial scheme, with six sowing depths (0.5, 1.0, 2.0, 4.0, 8.0, and 12.0 cm) associated with four solar radiation intensities (100%, 70%, 50%, and 30%) obtained through the use of shading screens. Seedling emergence capacity was evaluated daily to obtain the emergence percentage and speed index. Plant height, floral induction time, and plant dry matter at flowering were measured. Even when subjected to different solar radiation intensities, U. decumbens and C. echinatus seedlings emerged at all the sowing depths. Sowing between 2.0-and 4.0-cm depths favored the emergence of seedlings of U. decumbens and C. echinatus. However, sowing at 12-cm depth reduced the emergence of both species regardless of the solar radiation intensity. Urichloa decumbens plants grown under conditions of greater shading showed the lowest values of height and dry matter accumulation during flowering. High levels of shading facilitated only the etiolation of C. echinatus plants. Increased shading flowering time in both species compared to full sunlight.
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    Impact of Fungicide Application Timing Based on Soybean Rust Prediction Model on Application Technology and Disease Control
    (2022-09-01) Negrisoli, Matheus Mereb [UNESP]; Silva, Flávio Nunes da [UNESP]; Negrisoli, Raphael Mereb [UNESP]; Lopes, Lucas da Silva [UNESP]; Souza Júnior, Francisco de Sales [UNESP]; Freitas, Bianca Rezende de [UNESP]; Velini, Edivaldo Domingues [UNESP]; Raetano, Carlos Gilberto [UNESP]; Universidade Estadual Paulista (UNESP)
    The application of remote sensing techniques and prediction models for soybean rust (SBR) monitoring may result in different fungicide application timings, control efficacy, and spraying performance. This study aimed to evaluate the applicability of a prediction model as a threshold for disease control decision-making and to identify the effect of different application timings on SBR control as well as on the spraying technology. There were two experimental trials that were conducted in a 2 × 4 factorial scheme: 2 cultivars (susceptible and partially resistant to SBR); and four application timings (conventional chemical control at a calendarized system basis; based on the prediction model; at the appearance of the first visible symptoms; and control without fungicide application). Spray deposit and coverage at each application timing were evaluated in the lower and upper region of the soybean canopy through quantitative analysis of a tracer and water-sensitive papers. The prediction model was calculated based on leaf reflectance data that were collected by remote sensing. Application timings impacted the application technology as well as control efficacy. Calendarized system applications were conducted earlier, promoting different spray performances. Spraying at moments when the leaf area index was higher obtained poorer distribution. None of the treatments were capable of achieving high spray penetration into the canopy. The partially resistant cultivar was effective in holding disease progress during the crop season, whereas all treatments with chemical control resulted in less disease impact. The use of the prediction model was effective and promising to be integrated into disease management programs.
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    Lime and calcium-magnesium silicate cause chemical attributes stratification in no-till fields
    (2022-10-01) Antonangelo, João Arthur; Neto, Jayme Ferrari; Crusciol, Carlos Alexandre Costa [UNESP]; Zhang, Hailin; Alleoni, Luís Reynaldo F.; Austin Peay State University; Dom Bosco Catholic University; Universidade Estadual Paulista (UNESP); Oklahoma State University; Universidade de São Paulo (USP)
    The stratification of soil chemical properties under long-term no-till (NT) where different soil pH regimes are used and at different cropping-systems (CS) has yet to be studied. We aimed to evaluate the effect of the surface application of soil pH amendments on soil chemical attributes of stratified soil samples and their relationship with the subsequent yield of the soybean crop. The effect of the surface application of lime and calcium-magnesium silicate (CMS) on the chemical attributes of soil samples with increment depth (0–5, 5–10, 10–20, 20–40, and 40–60 cm) was evaluated. Also, their relationships with the subsequent soybean (Glycine max) yield on a tropical acidic soil under NT with four CS (SB: soybean─Brachiaria brizantha; SC: soybean─Crotalaria spectabilis; SF: soybean─fallow; and SW: soybean─ Triticum aestivum) were compared. The NT operations caused the stratification of all soil chemical attributes studied regardless of the CS and soil pH amendment. Application of lime or CMS significantly decreased exchangeable aluminum (Al) and potential acidity (H+Al), and increased pH, calcium (Ca), magnesium (Mg), silicon (Si), the sum of base (SB), and base saturation (BS%) in the upper soil layers (up to 10 cm) for most CS studied. Soil acidity parameters from 0 to 5 cm were related to soybean yield, and the stratification of H+Al led to a difference of 2-ton ha-1 soil amendment needed (p < 0.001) when soil is sampled from 0 to 5 cm in comparison to the 0–20 cm sampling.
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    Soil mineralogy and K reserves in soils from the Araguaia River valley, Brazil
    (2023-06-01) Volf, Marcelo R.; Benites, Vinicius M.; Azevedo, Antônio C.; Moraes, Milton F.; Tiritan, Carlos S.; Rosolem, Ciro A. [UNESP]; Sao Paulo Western University; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); Universidade de São Paulo (USP); Graduate Program of Tropical Agriculture; Universidade Estadual Paulista (UNESP)
    In humid tropical regions, intense weathering extensively depletes soil nutrients. However, soils in the Araguaia River Valley, Brazil, are not responsive to potassium (K) fertilization. To explore the reasons for this lack of responsiveness, an extensive exploratory soil sampling campaign was performed in areas of the valley with different land uses and soil management practices. Soil was sampled at depths of 0–20 cm and 20–40 cm, and exchangeable K (Ke) and non-exchangeable K (Kne) were assessed. The average soil Ke content in the region was 66.3 mg kg−1, above the minimum required value for crop growth. The soil Kne content ranged from one to five times the soil Ke content and was greater in the 20- to 40-cm layer than in the 0- to 20-cm layer. The linear correlation between Ke and Kne was significant only in the silt fraction. Mineralogical analysis of the clay and silt fractions of selected samples showed that the dominant minerals in the clay fraction were kaolinite, vermiculite with or without interlayer hydroxy-Al (HIV), illite, goethite, and gibbsite. Mica and feldspar were found in the silt fraction of several samples. In the silt and clay fractions, the main source of Kne was 2:1 phyllosilicates, which may be interstratifications of illite/vermiculite-hydroxy and illite/vermiculite. The results indicated that Urochloa spp. functions as a K scavenger in deep layers and promotes K biocycling in the system. An equation for predicting Kne extracted with nitric acid on the basis of soil Ke and silt contents was developed.
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    Logging Affects Genetic Diversity Parameters in an Araucaria angustifolia Population: An Endangered Species in Southern Brazil
    (2023-05-01) Roque, Rafael H.; Sebbenn, Alexandre M.; Boshier, David H.; Filho, Afonso F.; Tambarussi, Evandro V. [UNESP]; Universidade de São Paulo (USP); Instituto Florestal de São Paulo; University of Oxford; Universidade Estadual do Centro-Oeste (Unicentro); Universidade Estadual Paulista (UNESP)
    Araucaria angustifolia is an endangered species with more than 97% of its natural populations extinct. Logging of the species in the few remaining natural populations is highly restricted, though not readily accepted by farmers and logging companies. Consequently, political pressures have emerged for a return to logging of the species. Assessing the sustainability of such logging requires studies of a range of impacts on the remaining populations, including their genetic viability. We investigated the effect of selective logging on genetic diversity, intrapopulation spatial genetic structure (SGS), effective population size ((Formula presented.)), and pollen and seed dispersal in three A. angustifolia permanent sample blocks established in a remnant of Araucaria Forest in Brazil. In these sample blocks, three logging intensities were applied (LI: 18.4, 31.4, and 32.3% of trees). Microsatellite analysis was performed for all adult and juvenile trees pre- and post-logging saplings. After selective logging, the greatest loss of alleles and the greatest decrease in (Formula presented.) were observed from the highest LI. Logging increased SGS, while the distance and patterns of pollen and seed dispersal were different for both pre- and post-logging scenarios, with pollen dispersed over greater distances than seed. Pollen dispersal distance post-logging and seed dispersal distance pre- and post-logging decreased with the increased distance between parents. After logging, (Formula presented.) reduced from 27.7 (LI = 31.4%) to 28.8 (LI = 18.4%) and 39.5% (LI = 32.3%), and some alleles were lost. Despite this, the loss of these alleles may be compensated for in subsequent generations, considering that logging resulted in changes such as an increase in the rate and distance of pollen immigration. Under the conditions evaluated in this study, selective logging of A. angustifolia is not adequate. To achieve truly sustainable forest logging, new rules that combine higher minimum DBH, lower logging intensity, and longer cutting cycles must be adopted. Furthermore, extensive genetic studies must be performed before logging any individual from a natural population.
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    Silicon Fertilization in Sugarcane Drought-Contrasting Cultivars Subjected to Water Deficit at the Ripening Phase
    (2023-01-01) Sartori Camargo, Mônica; Baltieri, Gustavo Jonas; dos Reis, André Rodrigues [UNESP]; Pereira, Hamilton Seron; de Almeida Silva, Marcelo [UNESP]; Agência Paulista de Tecnologia dos Agronegócios (APTA); Faculdade de Tecnologia de Piracicaba; Universidade Estadual Paulista (UNESP); Universidade Federal de Uberlândia (UFU)
    Silicon (Si) could contribute to maintaining nutrient uptake, above-ground and root system biomass, enhancing sugar yield in sugarcane under water deficit at the ripening phase, but results are still scarce. This study aims to determine whether water deficit during the ripening phase causes deleterious effects on the biomass of green leaf, straw, stalk, and root system, nutrient uptake, and sugar accumulation of two drought-contrasting sugarcane cultivars, and whether Si alleviates these effects. An experiment was conducted in pots under greenhouse conditions using a randomized factorial design with two sugarcane cultivars (RB86-7515; RB85-5536), two Si rates (equivalent to 0 and 1000 kg ha−1 Si) as silicate, and the absence (well-watered, WW) or presence of water deficit (WD) during the ripening phase. There was an independent effect of water deficit, cultivar, and Si in soil on plant results. Water deficit decreased concentrations of Si, Ca, Fe, and B in leaves, leaf biomass by 19%, and sugar content by 27%. RB85-5536 showed the highest concentrations of Si, Ca and lower leaf biomass. Si increased soluble Si, base saturation in soil, Si, and Mg in plant, and sugar by 30%, and reduced Fe, and B in the root, straw by 7.3%, stalk biomass by 9.8%. The effects of water deficit were not intense at the ripening phase and caused decreased leaf biomass and enhanced sugar accumulation. Si, in turn, contributed to decreased straw biomass because of Si deposition, maintenance of green leaves, and increased sugar production with or without water deficit.
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    Higher lime rates for greater nitrogen recovery: A long-term no-till experiment labeled with 15N
    (2023-08-01) Bossolani, João William [UNESP]; Crusciol, Carlos Alexandre Costa [UNESP]; Mariano, Eduardo [UNESP]; Moretti, Luiz Gustavo [UNESP]; Portugal, José Roberto [UNESP]; Fonseca, Mariley [UNESP]; Momesso, Letusa [UNESP]; Côrt, Andressa Selestina Dalla [UNESP]; Costa, Vladimir Eliodoro [UNESP]; Cantarella, Heitor; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP); Soils and Environmental Resources Center
    Context or problem: Soil acidity limits crop growth and yield all over the world. Low grain yields is usually associated with poor soil fertility; however, little attention has been given to the nitrogen-based fertilizer use efficiency in soils managed with lime. Objective: Given the current scenario of uncertainties regarding the availability and prices of fertilizers, our study aimed to understand how maize intercropped with ruzigrass and soybean plants develop in long-term soils managed with lime rates, and what the fate of the 15N–labeled ammonium sulfate [(15NH4)2SO4] applied in the soil-plant system. Methods: The treatments consisted of four dolomitic lime rates applied to the soil surface [control, half the recommended lime rate (½ RLR), full recommended lime rate (1 RLR) and double the recommended lime rate (2 RLR)]. Results: The higher lime rate (2 RLR) improved fertility, carbon and nitrogen stocks in the soil profile, and grain and/or stover production of maize, ruzigrass and soybean. As a consequence, maize and ruzigrass recovered a high amount of 15N-fertilizer. On the other hand, soybean recovered less 15N-fertilizer, regardless of treatment, but a greater amount was found in acidic soils. At the end of the maize and soybean growth cycles, our results showed that in 2 RLR-amended soil, the 15N unrecovered was 71% lower than control. Finally, our results suggested that the use of low lime rates (½ RLR) may increase the 15N losses potential to deep layers, whereas low amounts of 15N were found in the subsoil when higher lime rates were applied. Conclusions and implications: Soil acidity management through higher lime rates leads, over time, to increased soil fertility, resulting in a favorable environment for plant growth and the use of nitrogen fertilizers. In this way, it is possible to obtain a more productive and less costly agricultural system, and with less potential to pollute the environment.