A utilização de inibidores de nitrificação pode ser uma alternativa interessante para aumentar a eficiência do uso do fertilizante nitrogenado em diversas culturas, porém, essa alternativa vem sendo pouco estudada em condições de solo e clima do Brasil. Assim, objetivou-se com esse trabalho avaliar a eficiência do inibidor de nitrificação fosfato de 3,4-dimetilpirazol (DMPP) em três solos com gradiente textural, bem como avaliar o destino do nitrogênio (N-NO3-, N-NH4+ e 15N) no solo, a absorção e o uso do nitrogênio (N-total e 15N) nas plantas de algodão. Três experimentos foram montados e desenvolvidos. No primeiro foi efetuada a incubação do solo em condições de laboratório para avaliar a inibição da nitrificação pelo DMPP aplicado na forma de ureia e sulfonitrato de amônio (SNA) em três solos (Neossolo Quartzarênico - NQ, Latossolo Vermelho Amarelo - LVA, Latossolo Vermelho - LV). No segundo experimento plantas de algodão foram cultivadas em colunas de lixiviação com os mesmos solos, recebendo ureia e sulfonitrato de amônio, com e sem DMPP como fonte de N. Foram avaliados a produção de matéria seca, o acúmulo de nutrientes nas plantas, a eficiência de uso do N pelo algodoeiro, a lixiviação e a quantidade de N mineral no solo após o cultivo do algodão por 60 dias. No terceiro experimento, plantas de algodão foram cultivadas também em colunas lixiviação, porém, com um solo de textura média (Latossolo Vermelho Amarelo), o qual recebeu três doses de N em cobertura (50, 100 e 150 kg ha-1 de N) na forma de ureia marcada no isótopo 15N, com e sem DMPP. Foram avaliados a produção de matéria seca, teor de N e recuperação do N aplicado na planta, lixiviação de N, teor de N-total, nítrico e amoniacal no solo, e recuperação do N aplicado no solo após o cultivo do algodão, por 90 dias. Melhores resultados foram obtidos com a aplicação do DMPP em ureia em relação ao SNA. No experimento de incubação, o DMPP foi capaz de manter menor o teor de nitrato nos três solos analisados. A nitrificação do N na ureia foi mais rápida comparado ao SNA, o que permitiu melhor desempenho do inibidor na ureia em dois dos três solos estudados. O efeito do DMPP aumentou seguindo a seguinte ordem: NQ>LVA>LV. O inibidor foi mais eficiente nos solos com menor teor de argila e matéria orgânica. O uso do DMPP em ureia aplicada no solo arenoso (NQ) reduziu significativamente a lixiviação de N e aumentou a produção de matéria seca, a eficiência do uso do N e a absorção de fósforo pela planta. No solo de textura média (LVA), sob irrigação intensa, o DMPP reduziu significativamente as perdas de N do sistema e aumentou a recuperação do 15N aplicado na planta e no solo, o que, porém, não se traduziu em maior produção de matéria seca provavelmente pelo N não ter sido limitante, devido à mineralização da matéria orgânica. As atividades das enzimas redutase do nitrato e urease não diferiram entre tratamentos com e sem DMPP / The use of nitrification inhibitors may be an interesting alternative to increase nitrogen fertilizer use efficiency in different crops, although it has been little studied in soil and climate conditions of Brazil. This study aimed to evaluate the efficiency of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) in three soils with textural gradient (represented by clay percentage), as well as to evaluate the fate of soil nitrogen (N-NO3-, N-NH4+ and 15N), nitrogen uptake, and N-use efficiency (total-N and 15N) by cotton plants. Three experiments were set and carried out in a controlled environment. In the first one, a laboratory incubation was performed to evaluate the inhibition of nitrification by DMPP applied to urea and ammonium sulfate nitrate (ASN) in three soils (Typic Quartzipsammnet - NQ, Typic Hapludox - LVA, Rhodic Hapludox - LV). In the second experiment, leaching columns with the same soils were planted with cotton receiving ammonium sulfate nitrate and urea with or without DMPP as nitrogen source. It were evaluated plant dry matter yield (shoot plus roots), nutrient uptake and nitrogen use efficiency by cotton plants, as well as the nitrogen leaching, and mineral nitrogen amount in the soil after cotton growth, for 60 days. In the third experiment, leaching columns with a medium textured soil (LVA) were planted with cotton and received three nitrogen rates in topdressing (50, 100 and 150 kg ha-1) as 15N-urea with and without DMPP. The production of dry matter, nitrogen content and recovery of applied N in the plant and soil, as well as the nitrogen leaching, total nitrogen, nitrate and ammonium in the soil were evaluated after cotton growth for 90 days. Best results were obtained with the application of DMPP to urea than in ASN. In the incubation experiment, the DMPP was able to maintain lower nitrate content in the three soils. The nitrification of nitrogen from urea was faster than the one from ASN, which allowed a better performance of the inhibitor in the urea in two out of three soils analyzed. The effect of DMPP increased in the following order: NQ> LVA> LV. The inhibitor was more effective in soils with lower clay and organic matter contents. The use of DMPP in urea applied on the sandy soil (NQ) significantly reduced N leaching and increased dry matter production, nitrogen use efficiency and phosphorus uptake by cotton plants. In a medium textured soil (LVA) under intense irrigation, DMPP significantly reduced N losses in the system and increased the recovery of applied 15N in plant and soil, which however did not translate into higher dry matter production because nitrogen was probably not limiting. The activity of the enzymes nitrate reductase and urease were not different between treatments with and without DMPP

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24239号 / 農博第2518号 / 新制||農||1094(附属図書館) / 学位論文||R4||N5410(農学部図書室) / 京都大学大学院農学研究科農学専攻 / (主査)教授 白岩 立彦, 教授 中﨑 鉄也, 教授 那須田 周平 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

The United States (US) has experienced a surge in water shortages and droughts in recent times. Water shortages can result from population growth, climate change, inadequate water management policies, and the improper use of available technologies. The existing data and research on water use associated with water management policy structures are limited. Many states in the US follow strict regulations on water discharge into streams to enforce water quality standards; however, water withdrawal restrictions from streams are limited and inadequate in terms of water management at times of low flow. In states such as Virginia (VA), the Virginia Department of Environmental Quality (VDEQ) requires a Virginia Water Protection (VWP) permit for all water withdrawals from VA's surface waters. However, under certain provisions of VWP regulations, users are exempted from having a permit. Such permit exemptions exist in many states and present a severe challenge to water supply management. Chapter 2 compares the impact of permit exemptions on surface water availability and drought flows and compares these impacts to the relatively well-studied risks presented by dry climate change and demand growth in Virginia (VA). It was observed that in some regions, the impacts under the exempt user scenario were higher than those under the dry climate change scenario. In addition, water supply managers and government agencies use user-reported water withdrawal data to develop water management programs. Irrigated agriculture is the largest source of water consumption in the US. However, water-reporting regulations exempt users from withdrawing water for irrigation under a certain threshold. Moreover, as water is not metered, users often do not report their irrigation water use, resulting in considerable uncertainty about the impacts of irrigation withdrawals, which could potentially impact other water users, lead to water shortages or conflicts, and negatively impact stream ecology. Chapter 3 focuses on developing a novel methodology for quantifying unreported irrigation water withdrawals using publicly available USDA-Census and USDA-IWMS datasets. This method was used to evaluate the unreported water withdrawals in the VA. Finally, water use practices at the field level intersect with other environmental issues at a larger scale. For example, irrigation practices can influence nutrient uptake and transport at the field level. Insufficient water for irrigation, especially during critical growth stages, results in yield and economic losses and reduces agricultural productivity. However, excessive irrigation can lead to wasted water and energy as well as runoff and leaching of nutrients and agricultural chemicals. Therefore, the adoption of technological advancements at the field scale can reduce the amount of water needed to fulfill the needs while mitigating any nutrient impacts on the soil due to the excessive use of water. This is highly important when fertilizer prices are always high. Chapter 4 focuses on quantifying the impact of the use of short-term weather forecast data in irrigation scheduling on nutrient and water use efficiency in humid climates: experimental results for corn and cotton. It was found that irrigation scheduling using short-term weather forecast data is helpful for improving the nutrient and water use efficiency of corn. For cotton, nutrient and water use efficiency are highly influenced by irrigation and precipitation with respect to the growth stage. / Doctor of Philosophy / Water shortages in the US have increased in recent times owing to climate change. Water demand is expected to increase in the future due to population growth and economic development in certain regions. Water supply planning is significantly influenced by water policy regulations. Water withdrawal regulations mandate a water withdrawal permit for making withdrawals in many states across the US. However, due to provisions in the same water regulations, certain users are exempt from taking a water withdrawal permit. One example of such users is grandfathered users who had a water withdrawal permit before July 1, 1989, in Virginia. Such exemptions are a severe challenge to the management of water supply, as exempt withdrawal amounts are generally high. We studied the impacts of these exempt users on VA's water resources of VA and compared them with the impacts of dry climate change and 2040 demand growth in Chapter 2. The results indicate that the impact of exempt users is higher than that of climate change in some regions across VA. Additionally, water-reporting regulations require users to report irrigation water withdrawals. However, users below the reporting threshold were excluded from reporting. Some users might underreport or do not comply with the water withdrawal regulations. These user-reported data are often used in developing water management plans, which may become ineffective owing to incomplete water use data. Chapter 3 focuses on the development of a data-based approach for quantifying unreported irrigation water withdrawals. This method would be transferable to any other state across the US. We compared the estimated irrigation withdrawals with reported irrigation withdrawals across the VA and generated unreported withdrawals at the county level in the VA. Finally, at the field level, irrigation can highly influence the nutrient uptake of plants. Excess irrigation may result in the removal of nutrients below the roots of the plant or may be removed by surface runoff, making it unavailable for plant uptake. Along with the economic impacts of unused fertilizer and loss in yield, unused nutrients may impact the environment and water bodies. Chapter 4 focuses on the impact of short-term weather forecast data on the irrigation scheduling of corn and cotton in humid climates. We found that weather-informed irrigation is helpful in increasing the nutrient and water use efficiency of corn. For cotton, the results were highly affected by precipitation and irrigation with respect to the growth stage of cotton.

The use of nitrogen (N) fertilizers is both costly to farmers and contributes to environmental degradation. N applied to wheat accounts for 18% of N applied to farmland globally, making it a prime target for reducing and optimizing N application. Chapter I is a review on nitrogen use efficiency (NUE) in wheat, with emphasis on breeding efforts and genetic resources available to increase NUE. The concept of effective use of nitrogen (EUN) as yield per unit N applied as a measure of N use, is also introduced. Chapter II is a study using two bi-parental double haploid families to evaluate genetic variability of both the genetic main effects (intercept) and linear response to N (slope) and determine the feasibility of selection for EUN in wheat. Using cross validation, a genomic prediction accuracy of 0.68 for intercept and 0.50 for slope was found, indicating that EUN is under genetic control and can be selected for. The prospect of breeding for EUN under limited resources, i.e., using fewer N rates and fewer experimental plots, is also explored. It was found that two different N treatments can be used to produce accurate predictions of intercept and slope as high as 0.98 and 0.95, respectively. Chapter III uses the same population described in chapter II to further investigate feasibility of selection for EUN using a normalized difference vegetation index (NDVI) obtained from multi-spectral aerial images gathered throughout the growing season. Cumulative photosynthesis across the growing season was estimated by integration across the NDVI curve, and compared to grain yield estimates to determine the efficacy of aerial imaging to identify high EUN lines. NDVI values and the area under the NDVI curve were able to predict yield and had the strongest ability to predict yield in moderate to low N treatments, with R2 values as high as 0.81 and 0.78 respectively. / Master of Science / Chapter I is a review on nitrogen use efficiency (NUE) in wheat, with emphasis on breeding efforts and genetic resources available to increase NUE. The concept of effective use of nitrogen (EUN) defined as grain yield per unit N applied, is contrasted to NUE as a more economic breeding goal. Chapter II uses two bi-parental mapping populations to evaluate genetic variability of both the genetic main effects and the linear response to N and determine the feasibility of selection for EUN in wheat. The efficacy of genomic prediction for EUN is explored and the prospect of breeding for EUN under limited resources is also explored. Chapter III uses the same populations described in chapter II to further investigate the feasibility of selection for EUN using a normalized difference vegetation index (NDVI) obtained from multi-spectral aerial images gathered throughout the growing season. Cumulative photosynthesis across the growing season was estimated and found to be predictive of grain yield estimates at accuracies ranging from 0.31 to 0.78.

Soybean and wheat are important crop species due to their significance for human consumption, animal feed, and industrial use. However, increasing global population and worsening climate change have put a major strain on the production system of these crops. Natural disasters such as flooding and drought can severely impact growth and productivity of these crops. In addition, increased application of synthetic nitrogenous fertilizers to meet the global food demand has led to environment related issues. Therefore, with a goal of understanding mechanisms of flooding and drought tolerance in soybean and nitrogen-use-efficiency in wheat, we explored their physiological and transcriptomic regulation. We characterized the fundamental acclimation responses of soybean to flooding and drought and compared the metabolic and transcriptomic regulation during the stresses in a tissue-specific manner. We demonstrated the dynamic reconfiguration of gene expression and metabolism during flooding, drought, and recovery from these stresses. Our study displayed that flooding triggers more dramatic adjustments than drought at the transcriptional level. We also identified that the soybean genome encodes nine members of group VII ERF genes and characterized their responses in leaves and roots under flooding and drought. Based on the expression patterns, it is estimated that two of the nine genes are promising candidate genes regulating tolerance to submergence and drought. In addition, our genome-scale expression analysis discovered commonly induced ERFs and MAPKs across both stresses (flooding and drought) and tissues (leaves and roots), which might play key roles in soybean survival of flooding and drought. In wheat, we evaluated the effect of three different nitrogen rates on yield and its components across four diverse soft red winter wheat genotypes. The cultivar Sisson displayed superior performance in grain yield and nitrogen use efficiency at low nitrogen levels. Our results suggested that improvement of nitrogen use efficiency in low nitrogen environments can be achieved through the selection of three components: grain number/spike, 1000-seed weight, and harvest index. Overall, this study has advanced our understanding of how plants respond to abiotic stresses such as flooding, drought, and nutrient limitation conditions. / Ph. D. / Soybean and wheat are commercially important crop throughout the world. Soybean is a major source of protein and oil for humans, livestock and industrial products including biofuel production. Similarly, wheat is a major source of food products such as bread, pasta, and cookies. However, increasing global population and worsening climate change have put a major strain on the production system of these crops. Natural disasters such as flooding and drought are on the rise, which have severely impacted soybean growth and productivity. In addition, increased application of synthetic nitrogenous fertilizers in wheat production to meet the global food demand has led to environment related issues. Therefore, a mechanistic understanding of flooding and drought tolerance in soybean and nitrogen use efficiency in wheat is of utmost importance. The knowledge obtained from these studies can aid in the development of new varieties in these crops. Here, we carried out our study on soybean by imposing either complete submergence or restricting water supply to characterize the responses to these stresses in shoot and root systems. We found several compounds and genes that were altered distinctly under these two water-related stresses. In addition, we identified some promising genes that can significantly regulate tolerance in soybean to flooding and drought in soybean. To study wheat nitrogen use efficiency, we selected four diverse soft red winter wheat varieties and grew them under three nitrogen levels. We found that the cultivar Sisson has the lowest yield penalty among the four varieties resulting from low nitrogen conditions. In addition, we also demonstrated that three yield traits (grain number per spike, 1000-seed weight, and harvest index) are important selection targets to develop high nitrogen use efficiency varieties.

Misturas de ureia (U) e ureia revestida com enxofre e polímero (URP) podem ser uma alternativa para melhorar a eficiência de utilização de nitrogênio (EUN) e reduzir custos quando aplicadas de uma única vez em cultivos agrícolas. Em experimentos de campo foram investigados diferentes índices de EUN (eficiência de recuperação aparente (ERA), eficiêncica fisiológica (EF), eficiência de utilização interna (EUI), eficiência agronômica (EA) e fator parcial (FPP) do N aplicado) e o acúmulo e particionamento de macronutrientes no milho (Zea mays L.) com misturas de U e URP na dose de 180 kg ha-1 aplicados totalmente na semeadura em Latossolo Vermelho Amarelo distrófico (LVAd) e Latossolo Vermelho distrófico (LVd). Foi incluído tratamento com ureia em manejo convencional (UMC). As misturas de URP+U foram incorporadas em faixa, 5 cm abaixo e 10 cm ao lado da linha de semeadura. As plantas foram amostradas em quatro estádios e divididas em quatro frações da planta (partes da planta) para a determinação de nutrientes. No LVAd, tratamentos com 100%URP, 70%URP+30%U e 60%URP+40%U apresentaram maior produtividade que o tratamento controle; 100%U e UMC tiveram menor EF e EUI que o 100%URP; todos os tratamentos com N apresentaram maior acúmulo total de N e massa seca que o controle em R6; a proporção de 70%URP+30%U apresentou maior acúmulo de S total do que o controle e UMC em R6. Não foram verificadas diferenças entre os tratamentos para produtividade, índices de EUN e acúmulo total de nutrientes no LVd. Em experimentos em casa de vegetação foram avaliados a condutividade elétrica (CE) e o pH do solo, altura, diâmetro, massa seca e acúmulo de N no desenvolvimento inicial de plantas de milho usando a mistura de 70%URP+30%U aplicada em faixa na semeadura do milho, das seguintes maneiras: 1) aplicando-se uma dose equivalente a 180 kg ha-1 de N em diferentes posições (5, 10 e 15 cm abaixo e 0, 5 e 10 cm ao lado da linha de semeadura) em um Latossolo Vermelho eutrófico (LVe) e comparando com 100%U; 2) variando as doses de N (equivalente a 0, 90, 180, 360 e 540 kg ha-1 de N) em uma posição considerada adequada (15 cm abaixo e 10 cm ao lado da linha de semeadura) no LVe e no LVAd. As aplicações feitas 15 cm abaixo da linha de semeadura apresentaram maior CE na linha do fertilizante na camada 9-18cm, pH na linha do fertilizante, massa seca total e N total que 5 e 10 cm. 70%URP+30%U apresentou maior altura, massa seca total e N total que 100%U quando aplicados abaixo da linha de semeadura. Nas aplicações 10 cm ao lado da linha de semeadura observou-se menor CE na linha do fertilizante comparado com as de 0 cm. No LVAd, massa seca total e N total apresentaram comportamento quadrático em resposta ao aumento da dose de N. Misturas de U e URP são eficientes quando aplicadas na semeadura do milho e elevadas doses interferem no desenvolvimento inicial de plantas de milho mesmo em uma posição considerada adequada no LVAd. / Blends of urea (U) and polymer sulfur coated urea (PSCU) can be an alternative to improve nitrogen (N) use efficiency (NUE) and reduce costs when applied in a single application in agricultural crops. Different indices of NUE (apparent crop recovery applied N (RE), physiological efficiency of applied N (PE), internal utilization efficiency of N (IE), agronomic efficiency of applied N (AE), partial factor productivity of applied N (PFP)) were investigated in field experiments, as well as nutrient uptake and partitioning in corn (Zea mays L.) with blends of U and PSCU applied in a single application of 180 kg N ha-1 at sowing in a Typic Haplustox and Rhodic Haplustox. It was included a treatment with urea in conventional management (UCM). The blends of U and PSCU were incorporated in a band 5 cm below and 10 cm to the side of the seed row. Plants were sampled at four growth stages and divided into four fractions for nutrient determination. In the Typic Haplustox, treatments with 100%PSCU, 70%PSCU+30%U and 60%PSCU+40%U had higher grain yield than control treatment (without N application); treatments with 100%U and UCM had lesser PE and IE than 100%PSCU; all the N treatments had higher total biomass and total N uptake than control at physiological maturity (R6); treatment with 70%PSCU+30%U had higher total S uptake than control and UCM at R6. There weren\'t differences between treatments for grain yield, indices of NUE, and total nutrient uptake at R6 in the Rhodic Haplustox. In greenhouse experiments, electrical conductivity (EC) and pH of soil, height, diameter, dry weight and nitrogen uptake in early plant growth were evaluated using a blend of 70%PSCU+30%U applied in a band at sowing maize in the following ways: 1) applying a rate equivalent to 180 kg N ha-1 in different positions (5 , 10 and 15 cm below and 0, 5 and 10 cm to the side of the seed) in a Rhodic Eutrustox and comparing with 100%U; 2) varying rates (equivalent to 0, 90, 180, 360, 540 kg N ha-1) in a position considered adequate (15 cm below and 10 cm to the side of the seed) in a Rhodic Eutrustox and Typic Haplustox. The N fertilizer application 15 cm below of the seed had higher EC in fertilizer row at 9-18cm, pH in fertilizer row, total dry weight and total N uptake than 5 and 10 cm below of the seed. The treatment with 70%PSCU+30%U had higher height, total dry weight and total N uptake than 100%U in the application 0 cm to the side of the seed. The N fertilizer application 10 cm to the side of seed had lesser EC in the fertilizer row than 0 cm. In the Typic Haplustox, total dry weight and total N uptake had quadratic behavior in response to increase N rates. Blends of U and PSCU are efficient when applied at corn sowing and can affect early plant growth at high rates even in a position considered adequate in Typic Haplustox.

Devido ao aprimoramento das práticas silviculturais e do melhoramento genético para seleção de genótipos mais produtivos, a produtividade do Pinus taeda no Brasil é reconhecida entre as maiores do mundo. Mesmo com alta produtividade em determinados sítios, sua variação é consideravelmente grande. Sabe-se que a disponibilidade de água, luz e nutrientes são fatores essenciais para a produção de madeira, onde a eficiência de uso desses recursos influenciam nesta variação do produtividade. Contudo, a ausência de fertilização em plantios de Pinus é majoritária nas áreas comerciais no Brasil, devido ao bom crescimento em solos de baixa fertilidade e por dificilmente apresentarem deficiência visual de nutrientes. Para compreender quais fatores influenciam na produção e partição de biomassa, se faz necessário o estudo da ecologia da produção. Diante disso, o presente trabalho tem como principais objetivos: i) estudar a influência de diferentes classes de solo no crescimento do Pinus taeda; ii) estudar a resposta da produtividade da espécie submetida à fertilização e ao desbaste; iii) avaliar a interceptação de luz; e iv) estimar a eficiência do crescimento (EC), uso da luz (EUL) e do nitrogênio (EUN) em povoamentos de Pinus taeda no sul do Brasil. Utilizou-se para este estudo parcelas quadrigêmeas da rede experimental do programa de Produtividade Potencial do Pinus no Brasil, as quais compõem um gradiente edafoclimático nos estados do Paraná e de Santa Catarina. As parcelas foram submetidas aos seguintes tratamentos: controle (C), fertilizado (F), desbastado (D), desbastado e fertilizado (DF). Foi calculado o índice de sítio, o incremento corrente anual, o incremento médio anual, índice de uniformidade do povoamento, a produtividade primária líquida de madeira e o índice de área foliar (IAF). Realizou-se análises de solo (0-20 cm) e foliar. Os dados das variáveis climáticas calculadas foram obtidos das estações meteorológicas mais próximas aos sítios avaliados. A produtividade mínima e máxima das parcelas controle foi de, respectivamente, 20,3 e 56,9 m³ ha-1 ano-1 com idade média de 13 anos. Houve efeito significativo dos tratamentos F e DF, com ganho máximo no estoque de volume por parcela de 33 e 63%, respectivamente. A resposta da fertilização e da fertilização com desbaste ocorreram em áreas menos férteis e com menor teor de matéria orgânica do solo. A uniformidade dos povoamentos correlacionou-se positivamente com as parcelas de maior área basal em 2014 e com a EC, EUL e EUN calculadas em 2013. Os valores médios da EC, EUL e EUN aos 12,4 anos de idade foram de 2,1 Mg ha-1 IAF-1, 0,55 g MJ-1 e 93 kg lenho kg-1 N ano-1, respectivamente. Houve relação linear positiva da EC, EUL e EUN com a produção de biomassa total acima do solo. Ocorreu maior influência das variáveis edáficas na eficiência do uso dos recursos naturais comparado com as variáveis climáticas. / Due to the improvement of silviculture practices and breeding for the selection of more productive genotypes, the loblolly pine productivity in Brazil is recognized as one of the biggest in the world. Even with the high productivity at certain sites, its variation is large. It is known that the availability of water, light and nutrients are essential for the wood production, and that the use efficiency of these resources influences the productivity variation. However, the absence of fertilization in pine plantations is majority in the commercial areas in Brazil due to good growth in low fertility soils and it hardly presents visual nutrient deficiency. To understand which factors influence the production and biomass partitioning, it is necessary to study the production ecology. Thus, the present work has as main objectives: i) to study the influence of different soil classes in loblolly pine growth; ii) to study the productivity response submitted to fertilization and thinning; iii) to evaluate the light interception; and iv) to estimate the growth efficiency (GE), use of light (LUE) and nitrogen (NUE) in loblolly pine stands in southern Brazil. For this study, it was used quadriplots from the experimental network of Pinus Potential Productivity in Brazil program, which composes an edaphoclimatic gradient in Parana and Santa Catarina states. The plots were submitted to the following treatments: control (C), fertilized (F), thinning (T), thinning and fertilized (TF). It was calculated the site index, the annual increment, the mean annual increment, the stand uniformity index, wood net primary productivity and the leaf area index (LAI). The soil (0-20 cm) and foliar analyzes were held. Data from the calculated climate variables was obtained from the closest weather stations to the evaluated sites. The minimum and maximum productivity of control plots were, respectively, 20.3 and 56.9 m³ ha-1 yr-1 with an average age of 13 years. There was a significant effect of F and TF treatments, with maximum gain in volume stock of 33 and 63%, respectively. The response of fertilization and fertilization with thinning occurred in less fertile areas and with lower soil organic matter content. The stands uniformity correlated positively with the basal area in 2014 and the GE, LUE and NUE calculated in 2013. The mean values of GE, LUE and NUE at the average age of 12,4 years were 2.1 Mg ha-1 LAI-1, 0.55 g MJ-1 and 93 kg wood kg-1 N year-1, respectively. There was a positive linear relationship of GE, LUE and NUE with the production of total biomass above ground. The soil variables influenced more on the use efficiency of natural resources than climatic variables.

Misturas de ureia (U) e ureia revestida com enxofre e polímero (URP) podem ser uma alternativa para melhorar a eficiência de utilização de nitrogênio (EUN) e reduzir custos quando aplicadas de uma única vez em cultivos agrícolas. Em experimentos de campo foram investigados diferentes índices de EUN (eficiência de recuperação aparente (ERA), eficiêncica fisiológica (EF), eficiência de utilização interna (EUI), eficiência agronômica (EA) e fator parcial (FPP) do N aplicado) e o acúmulo e particionamento de macronutrientes no milho (Zea mays L.) com misturas de U e URP na dose de 180 kg ha-1 aplicados totalmente na semeadura em Latossolo Vermelho Amarelo distrófico (LVAd) e Latossolo Vermelho distrófico (LVd). Foi incluído tratamento com ureia em manejo convencional (UMC). As misturas de URP+U foram incorporadas em faixa, 5 cm abaixo e 10 cm ao lado da linha de semeadura. As plantas foram amostradas em quatro estádios e divididas em quatro frações da planta (partes da planta) para a determinação de nutrientes. No LVAd, tratamentos com 100%URP, 70%URP+30%U e 60%URP+40%U apresentaram maior produtividade que o tratamento controle; 100%U e UMC tiveram menor EF e EUI que o 100%URP; todos os tratamentos com N apresentaram maior acúmulo total de N e massa seca que o controle em R6; a proporção de 70%URP+30%U apresentou maior acúmulo de S total do que o controle e UMC em R6. Não foram verificadas diferenças entre os tratamentos para produtividade, índices de EUN e acúmulo total de nutrientes no LVd. Em experimentos em casa de vegetação foram avaliados a condutividade elétrica (CE) e o pH do solo, altura, diâmetro, massa seca e acúmulo de N no desenvolvimento inicial de plantas de milho usando a mistura de 70%URP+30%U aplicada em faixa na semeadura do milho, das seguintes maneiras: 1) aplicando-se uma dose equivalente a 180 kg ha-1 de N em diferentes posições (5, 10 e 15 cm abaixo e 0, 5 e 10 cm ao lado da linha de semeadura) em um Latossolo Vermelho eutrófico (LVe) e comparando com 100%U; 2) variando as doses de N (equivalente a 0, 90, 180, 360 e 540 kg ha-1 de N) em uma posição considerada adequada (15 cm abaixo e 10 cm ao lado da linha de semeadura) no LVe e no LVAd. As aplicações feitas 15 cm abaixo da linha de semeadura apresentaram maior CE na linha do fertilizante na camada 9-18cm, pH na linha do fertilizante, massa seca total e N total que 5 e 10 cm. 70%URP+30%U apresentou maior altura, massa seca total e N total que 100%U quando aplicados abaixo da linha de semeadura. Nas aplicações 10 cm ao lado da linha de semeadura observou-se menor CE na linha do fertilizante comparado com as de 0 cm. No LVAd, massa seca total e N total apresentaram comportamento quadrático em resposta ao aumento da dose de N. Misturas de U e URP são eficientes quando aplicadas na semeadura do milho e elevadas doses interferem no desenvolvimento inicial de plantas de milho mesmo em uma posição considerada adequada no LVAd. / Blends of urea (U) and polymer sulfur coated urea (PSCU) can be an alternative to improve nitrogen (N) use efficiency (NUE) and reduce costs when applied in a single application in agricultural crops. Different indices of NUE (apparent crop recovery applied N (RE), physiological efficiency of applied N (PE), internal utilization efficiency of N (IE), agronomic efficiency of applied N (AE), partial factor productivity of applied N (PFP)) were investigated in field experiments, as well as nutrient uptake and partitioning in corn (Zea mays L.) with blends of U and PSCU applied in a single application of 180 kg N ha-1 at sowing in a Typic Haplustox and Rhodic Haplustox. It was included a treatment with urea in conventional management (UCM). The blends of U and PSCU were incorporated in a band 5 cm below and 10 cm to the side of the seed row. Plants were sampled at four growth stages and divided into four fractions for nutrient determination. In the Typic Haplustox, treatments with 100%PSCU, 70%PSCU+30%U and 60%PSCU+40%U had higher grain yield than control treatment (without N application); treatments with 100%U and UCM had lesser PE and IE than 100%PSCU; all the N treatments had higher total biomass and total N uptake than control at physiological maturity (R6); treatment with 70%PSCU+30%U had higher total S uptake than control and UCM at R6. There weren\'t differences between treatments for grain yield, indices of NUE, and total nutrient uptake at R6 in the Rhodic Haplustox. In greenhouse experiments, electrical conductivity (EC) and pH of soil, height, diameter, dry weight and nitrogen uptake in early plant growth were evaluated using a blend of 70%PSCU+30%U applied in a band at sowing maize in the following ways: 1) applying a rate equivalent to 180 kg N ha-1 in different positions (5 , 10 and 15 cm below and 0, 5 and 10 cm to the side of the seed) in a Rhodic Eutrustox and comparing with 100%U; 2) varying rates (equivalent to 0, 90, 180, 360, 540 kg N ha-1) in a position considered adequate (15 cm below and 10 cm to the side of the seed) in a Rhodic Eutrustox and Typic Haplustox. The N fertilizer application 15 cm below of the seed had higher EC in fertilizer row at 9-18cm, pH in fertilizer row, total dry weight and total N uptake than 5 and 10 cm below of the seed. The treatment with 70%PSCU+30%U had higher height, total dry weight and total N uptake than 100%U in the application 0 cm to the side of the seed. The N fertilizer application 10 cm to the side of seed had lesser EC in the fertilizer row than 0 cm. In the Typic Haplustox, total dry weight and total N uptake had quadratic behavior in response to increase N rates. Blends of U and PSCU are efficient when applied at corn sowing and can affect early plant growth at high rates even in a position considered adequate in Typic Haplustox.

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