O nitrogênio tem sido indispensável na formação, manutenção e recuperação de pastagens e seu efeito tem mostrado ser dependente do suprimento de enxofre, pela relação desses nutrientes no metabolismo vegetal. Objetivou-se: a) estudar combinações de doses de nitrogênio e de enxofre em solo suportando capim-Braquiária (Brachiaria decumbens) em degradação; b) avaliar o efeito do nitrogênio e do enxofre na eficiência no uso de água pelo capim; c) caracterizar as formas de nitrogênio e de enxofre no solo, antes, durante e após as adubações desses nutrientes; d) determinar a influência das combinações desses nutrientes em características nutricionais e produtivas do capim em recuperação. Coletaram-se amostras com plantas + solo em cilindros de 15 cm de diâmetro e 20 cm de profundidade num Neossolo Quartzarênico de uma pastagem em degradação. Utilizaram-se cinco doses de nitrogênio (0; 100; 200; 300 e 400 mg dm-3) e cinco doses de enxofre (0; 10; 20; 30 e 40 mg dm-3), combinadas em estudo de superfície de resposta baseado em desenho experimental composto central modificado de um fatorial 52 fracionado. Realizaram-se três cortes nas plantas com intervalos regulares de 30 dias. O fornecimento simultâneo de nitrogênio e enxofre na adubação aumentou a área foliar e a produção de massa seca, o número de perfilhos e melhorou a eficiência no uso de água pelo capim. A adubação com nitrogênio teve efeito isolado para o número de perfilhos e produção de massa seca no segundo e no terceiro crescimentos. O número de folhas foi influenciado pelas doses de nitrogênio e de enxofre de forma isolada, no primeiro crescimento e pelas doses de nitrogênio no segundo e no terceiro crescimentos. As relações entre as doses de nitrogênio e as de enxofre para as máximas produções foram de maneira geral em torno de 10:1. A adubação nitrogenada resultou em aumento na produção de massa, o comprimento e a superfície das raízes. O valor SPAD dependeu da combinação de doses de nitrogênio e de enxofre apenas no primeiro crescimento e teve efeito do nitrogênio no segundo e no terceiro crescimentos. As concentrações de nitrogênio e de enxofre no capim atingiram máximos valores nas doses mais elevadas. A baixa relação N:S de 7:1 no capim na não aplicação de nitrogênio indicou maior demanda de nitrogênio do que de enxofre. A interação entre as doses de nitrogênio e de enxofre não foi significativa para as características químicas avaliadas no solo. O pH do solo diminuiu quando o nitrogênio foi aplicado. A matéria orgânica no solo não variou após três períodos de crescimento do capim. A adubação com nitrato de amônio aumentou os teores de nitrogênio total, nitrogênio nítrico e nitrogênio amoniacal no solo. O teor de nitrogênio na forma amoniacal foi superior ao da forma nítrica no solo. A adubação com sulfato de cálcio aumentou os teores de enxofre total e de enxofre sulfato no solo. A aplicação principalmente de nitrogênio, mas também de enxofre, influenciou o estádio nutricional do capim-Braquiária e conseqüentemente a sua recuperação. / Nitrogen is required for pastures establishment, maintenance and production recovery, and its effect has depended on sulphur supply, for the relationship between these nutrients in plant metabolism. The objectives were: a) to study the combinations between nitrogen and sulphur rates in soil with Signal grass (Brachiaria decumbens) under degradation; b) to evaluate the effect of nitrogen and sulphur on the water use efficiency by grass; c) to determine the nitrogen and sulphur in the soil, before, in the course of the combinations between these nutrients on productive and nutritional characteristics of the recovering grass. Samples of plants plus soil were collected in cylinders of 15 cm diameter and 20 cm depth from an Entisol with a degrading pasture. Five rates of nitrogen (0; 100; 200; 300 and 400 mg dm-3) were combined with five rates of sulphur (0; 10; 20; 30 and 40 mg dm-3) in a response surface methodology based on a central composite design modified from a fractional 52 factorial. Three harvests were done after each 30 days of plants growth. The supply of nitrogen and sulphur together increased Signal grass leaf area, dry matter yield, number of tillers and improved the water use efficiency by the grass. Nitrogen rates had effects on the number of tillers and dry matter yield at the second and third harvests of the grass. The number of leaves was changed by both nitrogen and sulphur rates at the first growth, and by nitrogen rates at the second and third growths. Maximum dry matter yields were attained when nitrogen and sulphur rates were at about 10:1 ratio. Nitrogen supply affected grass roots by increasing roots dry weight, length and surface. SPAD values changed with combined rates of nitrogen and sulphur at the first growth, and with nitrogen rates at the second and third growths. Nitrogen and sulphur concentrations were at maximum when maximum rates of these nutrients were applied. The low 7:1 N:S ratio in the grass with no nitrogen supply suggested higher demand for nitrogen than sulphur. The interaction between nitrogen and sulphur rates was not significant for the evaluated soil chemical parameters. Soil pH decreased when nitrogen was applied. Soil organic matter content did not change after the growth periods of the grass. Ammonium nitrate supply resulted in increases in total nitrogen, nitrate and ammonium in the soil. Ammonium concentration in the soil was higher than nitrate. Calcium sulphate application resulted in increases in total sulphur and sulphate-sulphur in the soil. The application of mainly nitrogen, but also of sulphur, affected the nutritional status of Signal grass, and its recovery.

Existem inúmeros modelos de simulação de crescimento da cana-de-açúcar desenvolvidos no Brasil, mas o uso dos mesmos não é uma rotina na agroindústria canavieira. Paises como a França, África do Sul e Austrália desenvolveram modelos associados a softwares que são utilizadas com sucesso por proprietários de canaviais e pelas usinas a eles associadas. O objetivo do trabalho foi avaliar quatro variedades: R570, RB72454, NCo376 e SP83-2847, em condições brasileiras utilizando o Mosicas, desenvolvido pelo Centre de Coopération Internationale en Recherche Agronomique pour le Dévelopment como modelo de crescimento. A variedade NCo376, por suas características genéticas, foi a que apresentou o maior perfilhamento, superior ao das demais variedades. Em relação ao modelo Mosicas, o mesmo apresentou excelentes resultados, com valores simulados para massa seca da parte aérea, massa de colmos, produtividade, índice de área foliar e altura semelhantes aos observados no campo, indicando ter um bom potencial de uso no entendimento do processo de crescimento da cana-de-açúcar em condições brasileiras. / There are many sugarcane growth simulation models developed Brazil, but their application is not usual in the sugarcane industry. Countries like France, South Africa and Australia developed models using computer softwares with successful application by sugarcane farmers and their associated mills. The aim of this research was to evaluate four varieties (R570, RB72454, NCo376 e SP83-2847) under Brazilian conditions using Mosicas, a growth simulation model developed by Centre de Coopération Internationale en Recherche Agronomique pour le Dévelopment. The NCo376 variety, because its genetic characteristics, presented the greatest number of tillers, superior than the others varieties. The Mosicas simulated results, for total shoot dry weight, stalks biomass, yield, leaf area index and height had good correlation with the observed values. The Mosicas model has a good potential for use in research for the understanding of sugarcane growth under Brazilian conditions.

A natureza e a magnitude das respostas morfogênicas em plantas forrageiras variam com a disponibilidade de fatores climáticos de crescimento e com as metas de manejo utilizadas, modificando as características estruturais do dossel forrageiro. Nesse cenário, intensidades de desfolhação determinam alterações de forma e função nas plantas forrageiras que, por sua vez, definem e caracterizam estratégias de crescimento e perenização e a resistência das plantas ao pastejo. O objetivo deste estudo foi descrever e caracterizar as respostas morfogênicas e as características morfológicas do amendoim forrageiro (Arachis pintoi cv. Belmonte) submetido a intensidades de pastejo sob lotação contínua de janeiro de 2013 a março de 2014. Os tratamentos corresponderam a quatro níveis de intensidade de pastejo (severo - S, moderado - M, leniente - L, e muito leniente - ML) representados pelas alturas de pasto de 5, 10, 15 e 20 cm, e foram alocados às unidades experimentais (piquetes de 210 m2) segundo um delineamento de blocos completos casualizados, com 4 repetições. Foram identificados dez estágios de desenvolvimento das folhas de amendoim forrageiro que foram utilizados como referência para a realização das avaliações das respostas morfogênicas. Os folíolos apresentaram simetria dentro dos pares, não havendo a necessidade de mensuração dos quatro folíolos, apenas de um dos folíolos de cada par. A relação relativamente estável entre comprimento e largura dos folíolos permitiu que a área foliar fosse calculada de forma direta desde que um fator de correção (0,71) para a forma elíptica dos folíolos fosse utilizado. Estratégias distintas de crescimento foram utilizadas pelo amendoim forrageiro ao longo do ano. Estas foram caracterizadas por uma relação inversa entre as variáveis indicadoras de tamanho das plantas (comprimento do estolão, comprimento médio entre nós, entre pontos de crescimento e de enraizamento) e aquelas indicadoras de número de indivíduos (densidade de estolões, de nós, de pontos de crescimento e de pontos de enraizamento), com as maiores diferenças registradas nos pastos submetidos aos tratamentos L e VL. De forma geral, o aumento nas variáveis indicadoras de tamanho esteve associado com a diminuição daquelas indicadoras de número de indivíduos. Essa relação parece descrever um processo de segmentação das plantas caracterizado pela formação de unidades menores e autônomas durante o outono que voltam a aumentar de tamanho durante a primavera e verão. Esse processo viabiliza a reprodução clonal das plantas e contribui para a persistência da espécie na área. Pastos submetidos aos tratamentos S e M apresentaram maior taxa de aparecimento de folhas, menor filocrono e menor tamanho final de folhas que pastos submetidos aos tratamentos L e ML. Esse padrão de crescimento resultou em valores relativamente estáveis de IAF para as intensidades de pastejo. O IAF dos pastos variou apenas com a época do ano, refletindo a estacionalidade natural de crescimento das plantas. O amendoim forrageiro apresenta elevada plasticidade fenotípica e capacidade de adaptação ao pastejo, mas é preciso evitar estresses que possam interromper o processo de segmentação durante o outono, uma vez que isso poderia interferir com a perenização das plantas e favorecer o início de processo de degradação da área. / The nature and the magnitude of morphogenetic responses of forage plants vary with the availability of climatic growth factors and with management targets, modifying sward structural characteristics. In this context, defoliation intensity determines changes in plant form and function, which, in turn, define and characterise growth and perennation mechanisms and plant resistance to grazing. The objective of this study was to describe and characterise morphogenetic responses and morphological characteristics of forage peanut (Arachis pintoi cv. Belmonte) subjected to grazing intensities under continuous stocking from January 2013 to March 2014. Treatments corresponded to four levels of grazing intensity (severe - S, moderate - M, lenient - L, and very lenient - VL) represented by the sward management heights of 5, 10, 15 and 20 cm, and were allocated to experimental units (210 m2 paddocks) according to a complete randomised block design with four replications. Ten stages of leaf development were identified and used as reference for evaluations of plant morphogenetic responses. Leaflets were symmetrical within pairs, indicating the possibility of measuring leaf expansion in just one leaflet of each pair. The relatively stable leaflet length:width ratio allowed direct calculations of leaf area since a correction factor (0.71) for the elliptical form of the leaflets was used. Forage peanut used different growth mechanisms throughout the year. These were characterised by an inverse relationship between plant size (stolon length, internode length, distance between growing points and between rooting points) and plant number (stolon density, node density, growing point density and rooting point density), with greater differences recorded on swards subjected to treatments L and VL. In general, the increase in plant size was associated with a reduction in plant number. This relationship seems to describe a plant segmentation process that results in small autonomous units during autumn, that increase again in size during spring and summer. This process ensures plant clonal reproduction and favours persistence. Swards subjected to treatments S and M showed higher rates if leaf appearance, smaller phyllochron and smaller leaves than swards subjected to treatments L and VL. This resulted in LAI values relatively stable across treatments. LAI values varied only with season of the year, reflecting the seasonality of plant growth. Forage peanut is highly phenotypically plasticand adaptated to grazing, but stresses may interrupt the segmentation process during autumn, and this may interfere with plant perennation and favour the beginning of a degradation process.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-05-28T12:36:02Z No. of bitstreams: 1 BENEDITO FERREIRA BONIFÁCIO - DISSERTAÇÃO PPGSA PROFISSIONAL 2017..pdf: 1746823 bytes, checksum: 153584fa740b169801030661903c2cb4 (MD5) / Made available in DSpace on 2018-05-28T12:36:02Z (GMT). No. of bitstreams: 1 BENEDITO FERREIRA BONIFÁCIO - DISSERTAÇÃO PPGSA PROFISSIONAL 2017..pdf: 1746823 bytes, checksum: 153584fa740b169801030661903c2cb4 (MD5) Previous issue date: 2017-03-03 / Tendo em vista a importância socioeconômica da cultura da goiabeira, notadamente para a região nordeste do Brasil onde há limitada disponibilidade de água de boa qualidade, surge a necessidade do uso de águas salinas para produção agrícola implicando na necessidade do desenvolvimento de estratégias que possam viabilizar o seu uso. Nesse sentido, realizou-se a pesquisa com o intuito de avaliar os efeitos de diferentes doses de potássio combinadas com águas de distintos níveis salinos na produção de mudas para porta-enxerto de goiabeira. O experimento foi desenvolvido em casa de vegetação do Centro de Ciências e Tecnologia Agroalimentar da Universidade Federal de Campina Grande, Pombal - PB. O delineamento experimental foi em blocos casualizados, num esquema fatorial 5 x 4, com os tratamentos referentes à cinco níveis de condutividade elétrica da água de irrigação (CEa = 0,3; 1,1; 1,9; 2,7 e 3,5 dS m-1) em interação com quatro doses de potássio (70, 100, 130 e 160% de K) sendo a dose recomendada de 100% K (726 mg de K dm-3 de substrato) para mudas de goiabeira e quatro repetições, sendo cada parcela constituída por duas plantas úteis. A aplicação dos tratamentos teve início aos 40 dias após a emergência das plântulas (DAE). Os porta-enxertos foram avaliados aos 120 e 225 DAE, através da altura da planta, diâmetro do caule, número de folhas e área foliar; no período de 60 a 225 DAE foram mensuradas as taxas de crescimento absoluto e relativo para altura de planta e, aos 225 DAE a área foliar específica, as variáveis de fitomassa seca de caule, folhas, seca de raiz, parte aérea, total, relação raiz/parte aérea, razão de área foliar e o índice de qualidade de Dickson. A irrigação com água de CEa de até 1,9 dS m-1 possibilitou a formação de porta-enxerto de goiabeira cv. Paluma com redução aceitável em seu crescimento; dose de potássio de 798,6 mg de K dm-3 de substrato promoveu o maior crescimento em altura do porta-enxerto de goiabeira cv. Paluma aos 120 dias após a emergência; doses crescentes de K não atenuaram os efeitos nocivos dos sais sobre os porta-enxertos de goiabeira cv. Paluma; dose de 508,2 mg de K dm-3 de substrato favorece o acúmulo de fitomassa seca de caules de goiabeira cv. Paluma aos 225 DAE; irrigação com água de CEa 1,9 dS m-1 promove redução aceitável de 10% sobre a produção de fitomassa e qualidade dos porta-enxertos de goiabeira cv. Paluma; não houve interação significativa (sal x doses de K) sobre as variáveis estudadas. / Considering the socioeconomic importance of the guava crop, especially for the northeastern region of Brazil where there is limited availability of good quality water, the need arises for the use of saline waters for agricultural production, implying the need to develop strategies that can their use. In this sense, the research was carried out to evaluate the effects of different doses of potassium combined with waters of different salt levels in the production of seedlings for guava rootstock. The experiment was carried out in a greenhouse at the Agrifood Science and Technology Center of the Federal University of Campina Grande, Pombal - PB. The experimental design was a randomized complete block design, in a 5 x 4 factorial scheme, with the treatments referring to five levels of electrical conductivity of the irrigation water (CEw = 0,3; 1,1; 1,9; 2,7 and 3,5 dS m-1) in interaction with four doses of potassium (70, 100, 130 and 160% K) and the recommended dose of 100% K (726 mg K dm-3 substrate) for guava seedlings and four repetitions, each plot consisting of two useful plants. The treatments were started at 40 days after emergence of the seedlings (DAE). The rootstocks were evaluated at 120 and 225 DAE, through plant height, stem diameter, number of leaves and leaf area; in the period from 60 to 225 DAE, absolute and relative growth rates were measured for plant height and, at 225 DAE, the specific leaf area, stem dry matter, leaves, root dry matter, shoot, total ratio root/shoot, leaf area ratio and Dickson quality index. Irrigation with CEw water of up to 1,9 dS m-1 allowed the formation of a guava rootstock cv. Paluma with acceptable reduction in its growth; potassium dose of 798,6 mg of K dm-3 substrate promoted the highest growth in height of the guava rootstock cv. Paluma at 120 days after the emergency; increasing doses of K did not attenuate the harmful effects of the salts on guava rootstocks cv. Paluma; dose of 508,2 mg of K dm-3 of substrate favors the accumulation of dry phytomass of cv. Paluma at 225 DAE; irrigation with CEw water 1,9 dS m-1 promotes a 10% acceptable reduction on the phytomass production and quality of guava rootstocks cv. Paluma; there was no significant interaction (salt x doses of K) on the studied variables.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-05-11T14:12:16Z No. of bitstreams: 1 PDF - Augusto Barbosa de Queiroz.pdf: 1172161 bytes, checksum: de1ff94d7fdb83e524f6084e7a30c3b4 (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-06-13T20:27:20Z (GMT) No. of bitstreams: 1 PDF - Augusto Barbosa de Queiroz.pdf: 1172161 bytes, checksum: de1ff94d7fdb83e524f6084e7a30c3b4 (MD5) / Made available in DSpace on 2016-06-13T20:27:20Z (GMT). No. of bitstreams: 1 PDF - Augusto Barbosa de Queiroz.pdf: 1172161 bytes, checksum: de1ff94d7fdb83e524f6084e7a30c3b4 (MD5) Previous issue date: 2015-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Biological diversity can influence the structure and operation of communities in various ways, such as by altering the complementarity of resource use by species. Ways to quantify the beta and functional diversity are being developed and questions about the species relationships (phylogeny) or its functional characteristics should be better predictors of the ecological processes of comunidades.Podemos divide this essay into two chapters. The first chapter aims to partition the tree species diversity along an altitudinal gradient, which were allocated 375 points quadrants, divided into three altitudinal quotas. Through NMDS, we observe the ordination of three groups positively related to altitudinal quota that were inserted. The PERMIDISP showed that the community structure varied from 32.91 to 41.35 relative to the centroid of each cluster. The NMDS formed groups according to their position along the altitudinal gradient, so the composition and structure of the vegetation area are associated with altitude. So we suggest that alpha and beta diversity found in this study suggest a high heterogeneity in the dry forests of the Brazilian semiarid region. In the second chapter used the approach of functional diversity, the present study aims to identify and characterize functional types of plants, along an altitudinal grouped according to a set of attributes and foliar timber. Based on the hypothesis that it is possible to detect from a set of attributes selecionadosm cohesive functional groups of woody plants along an altitudinal. The dendrogram showed the formation of four functional groups, which were formed along the altitudinal gradient and were not related to the altitude. The G1 composed of five species, presents species with low leaf area and low specific leaf area, this group species invest in the sheet protection. The G2 consists of four species, grouped species with high specific leaf area, leaf area high and low wood density. G3 presented species with high wood density, average values of specific leaf area and low leaf area, consisting of three species of relatively slow growth. The G4 formed by species introduced high wood density, high specific leaf area and high leaf area. The formation of the functional groups was satisfactory to represent the role played by the group of species with similar characteristics in the forest. / A diversidade biológica pode influenciar a estrutura e o funcionamento das comunidades de diversas maneiras, como por exemplo, alterando a complementaridade no uso de recursos pelas espécies. Formas de quantificar a diversidade beta e funcional estão sendo desenvolvidas e perguntas sobre as relações de parentesco das espécies (filogenia) ou das suas características funcionais devem ser melhores previsores dos processos ecológicos das comunidades.Podemos dividir esta dissertação em dois capítulos. O primeiro capítulo tem o objetivo de particionar a diversidade de espécies arbóreas ao longo de um gradiente altitudinal, onde foram alocados 375 pontos quadrantes, dividido em três cotas altitudinais. Através da NMDS, observamos a ordenação de três agrupamentos relacionados positivamente com a cota altitudinal que estavam inseridos. A PERMIDISP, mostrou que a estrutura da comunidade variou entre 32,91 a 41,35 em relação ao centroide de cada agrupamento. A NMDS, formou grupos conforme a sua posição ao longo do gradiente altitudinal, assim a composição e a estrutura da vegetação da área estão associadas com a altitude. Assim sugerimos que a diversidade alfa e beta encontrada neste trabalho, sugerem um a elevada heterogeneidade nas florestas estacionais do semiárido brasileiro. No segundo capítulo utilizamos o enfoque da diversidade funcional, o presente estudo busca identificar e caracterizar tipos funcionais de plantas, ao longo de um gradiente altitudinal agrupados de acordo com um conjunto de atributos foliares e da madeira. Baseado na hipótese, de que é possível detectar, a partir de um conjunto de atributos selecionadosm grupos funcionais coesos de plantas arbóreas ao longo de um gradiente altitudinal. O dendrograma apontou a formação de quatro grupos funcionais, que foram formados ao longo do gradiente altitudinal e não foram relacionados com a altitude. O G1 composto por cinco espécies, apresenta espécies com baixa área foliar e baixa área foliar e specífica, neste grupo as espécies investem na proteção de folhas. O G2 formado por quatro espécies, agrupou espécies que apresentaram alta área foliar específica, alta área foliar e baixa densidade de madeira. O G3 apresentou espécies que apresentaram alta densidade de madeira, valores médios de área foliar específica e baixa área foliar, composto por três espécies de crescimento relativamente lento. O G4 formado por espécies que apresentara alta densidade de madeira, alta área foliar específica e alta área foliar. A formação dos grupos funcionais foi satisfatória ao representar o papel desempenhado pelo conjunto de espécies com características semelhantes na floresta.

Existem inúmeros modelos de simulação de crescimento da cana-de-açúcar desenvolvidos no Brasil, mas o uso dos mesmos não é uma rotina na agroindústria canavieira. Paises como a França, África do Sul e Austrália desenvolveram modelos associados a softwares que são utilizadas com sucesso por proprietários de canaviais e pelas usinas a eles associadas. O objetivo do trabalho foi avaliar quatro variedades: R570, RB72454, NCo376 e SP83-2847, em condições brasileiras utilizando o Mosicas, desenvolvido pelo Centre de Coopération Internationale en Recherche Agronomique pour le Dévelopment como modelo de crescimento. A variedade NCo376, por suas características genéticas, foi a que apresentou o maior perfilhamento, superior ao das demais variedades. Em relação ao modelo Mosicas, o mesmo apresentou excelentes resultados, com valores simulados para massa seca da parte aérea, massa de colmos, produtividade, índice de área foliar e altura semelhantes aos observados no campo, indicando ter um bom potencial de uso no entendimento do processo de crescimento da cana-de-açúcar em condições brasileiras. / There are many sugarcane growth simulation models developed Brazil, but their application is not usual in the sugarcane industry. Countries like France, South Africa and Australia developed models using computer softwares with successful application by sugarcane farmers and their associated mills. The aim of this research was to evaluate four varieties (R570, RB72454, NCo376 e SP83-2847) under Brazilian conditions using Mosicas, a growth simulation model developed by Centre de Coopération Internationale en Recherche Agronomique pour le Dévelopment. The NCo376 variety, because its genetic characteristics, presented the greatest number of tillers, superior than the others varieties. The Mosicas simulated results, for total shoot dry weight, stalks biomass, yield, leaf area index and height had good correlation with the observed values. The Mosicas model has a good potential for use in research for the understanding of sugarcane growth under Brazilian conditions.

O nitrogênio tem sido indispensável na formação, manutenção e recuperação de pastagens e seu efeito tem mostrado ser dependente do suprimento de enxofre, pela relação desses nutrientes no metabolismo vegetal. Objetivou-se: a) estudar combinações de doses de nitrogênio e de enxofre em solo suportando capim-Braquiária (Brachiaria decumbens) em degradação; b) avaliar o efeito do nitrogênio e do enxofre na eficiência no uso de água pelo capim; c) caracterizar as formas de nitrogênio e de enxofre no solo, antes, durante e após as adubações desses nutrientes; d) determinar a influência das combinações desses nutrientes em características nutricionais e produtivas do capim em recuperação. Coletaram-se amostras com plantas + solo em cilindros de 15 cm de diâmetro e 20 cm de profundidade num Neossolo Quartzarênico de uma pastagem em degradação. Utilizaram-se cinco doses de nitrogênio (0; 100; 200; 300 e 400 mg dm-3) e cinco doses de enxofre (0; 10; 20; 30 e 40 mg dm-3), combinadas em estudo de superfície de resposta baseado em desenho experimental composto central modificado de um fatorial 52 fracionado. Realizaram-se três cortes nas plantas com intervalos regulares de 30 dias. O fornecimento simultâneo de nitrogênio e enxofre na adubação aumentou a área foliar e a produção de massa seca, o número de perfilhos e melhorou a eficiência no uso de água pelo capim. A adubação com nitrogênio teve efeito isolado para o número de perfilhos e produção de massa seca no segundo e no terceiro crescimentos. O número de folhas foi influenciado pelas doses de nitrogênio e de enxofre de forma isolada, no primeiro crescimento e pelas doses de nitrogênio no segundo e no terceiro crescimentos. As relações entre as doses de nitrogênio e as de enxofre para as máximas produções foram de maneira geral em torno de 10:1. A adubação nitrogenada resultou em aumento na produção de massa, o comprimento e a superfície das raízes. O valor SPAD dependeu da combinação de doses de nitrogênio e de enxofre apenas no primeiro crescimento e teve efeito do nitrogênio no segundo e no terceiro crescimentos. As concentrações de nitrogênio e de enxofre no capim atingiram máximos valores nas doses mais elevadas. A baixa relação N:S de 7:1 no capim na não aplicação de nitrogênio indicou maior demanda de nitrogênio do que de enxofre. A interação entre as doses de nitrogênio e de enxofre não foi significativa para as características químicas avaliadas no solo. O pH do solo diminuiu quando o nitrogênio foi aplicado. A matéria orgânica no solo não variou após três períodos de crescimento do capim. A adubação com nitrato de amônio aumentou os teores de nitrogênio total, nitrogênio nítrico e nitrogênio amoniacal no solo. O teor de nitrogênio na forma amoniacal foi superior ao da forma nítrica no solo. A adubação com sulfato de cálcio aumentou os teores de enxofre total e de enxofre sulfato no solo. A aplicação principalmente de nitrogênio, mas também de enxofre, influenciou o estádio nutricional do capim-Braquiária e conseqüentemente a sua recuperação. / Nitrogen is required for pastures establishment, maintenance and production recovery, and its effect has depended on sulphur supply, for the relationship between these nutrients in plant metabolism. The objectives were: a) to study the combinations between nitrogen and sulphur rates in soil with Signal grass (Brachiaria decumbens) under degradation; b) to evaluate the effect of nitrogen and sulphur on the water use efficiency by grass; c) to determine the nitrogen and sulphur in the soil, before, in the course of the combinations between these nutrients on productive and nutritional characteristics of the recovering grass. Samples of plants plus soil were collected in cylinders of 15 cm diameter and 20 cm depth from an Entisol with a degrading pasture. Five rates of nitrogen (0; 100; 200; 300 and 400 mg dm-3) were combined with five rates of sulphur (0; 10; 20; 30 and 40 mg dm-3) in a response surface methodology based on a central composite design modified from a fractional 52 factorial. Three harvests were done after each 30 days of plants growth. The supply of nitrogen and sulphur together increased Signal grass leaf area, dry matter yield, number of tillers and improved the water use efficiency by the grass. Nitrogen rates had effects on the number of tillers and dry matter yield at the second and third harvests of the grass. The number of leaves was changed by both nitrogen and sulphur rates at the first growth, and by nitrogen rates at the second and third growths. Maximum dry matter yields were attained when nitrogen and sulphur rates were at about 10:1 ratio. Nitrogen supply affected grass roots by increasing roots dry weight, length and surface. SPAD values changed with combined rates of nitrogen and sulphur at the first growth, and with nitrogen rates at the second and third growths. Nitrogen and sulphur concentrations were at maximum when maximum rates of these nutrients were applied. The low 7:1 N:S ratio in the grass with no nitrogen supply suggested higher demand for nitrogen than sulphur. The interaction between nitrogen and sulphur rates was not significant for the evaluated soil chemical parameters. Soil pH decreased when nitrogen was applied. Soil organic matter content did not change after the growth periods of the grass. Ammonium nitrate supply resulted in increases in total nitrogen, nitrate and ammonium in the soil. Ammonium concentration in the soil was higher than nitrate. Calcium sulphate application resulted in increases in total sulphur and sulphate-sulphur in the soil. The application of mainly nitrogen, but also of sulphur, affected the nutritional status of Signal grass, and its recovery.

The effects of crop load and berry exposure on the composition of Marlborough Sauvignon blanc grapes and wine from the Brancott vineyard, Blenheim, were explored. Commercially grown, 2-cane and 4-cane Sauvignon blanc vines were used with a row orientation of north-south. Two exposure treatments were imposed in the following manner: complete leaf removal was undertaken in the fruit zone and 50% shade cloth was erected to give a uniform shading treatment to half the trial vines. Weekly thirty-berry and whole bunch samples were taken from each of the 32 plots with the exception of the veraison period when two samples per week were taken. Vine vigour was assessed using pruning and leaf area per vine data. Harvest occurred on different dates for 2-cane and 4-cane pruned vines so that fruit attained from both treatments had similar °Brix. Fruit was processed at the Lincoln University winery. Must analysis and wine analysis were undertaken. As expected, 4-cane vines had almost double the yield of 2-cane vines. Higher crop load significantly reduced leaf area per shoot and shoot thickness. Lower leaf area to fruit ratio for 4-cane berries resulted in delayed onset of veraison and slowed the rate of sugar accumulation. Crop load, which limited leaf area to fruit ratio, appeared to be the dominant factor in determining timing of grape physiological ripeness as expressed by °Brix over other factors such as fruit exposure. Malic acid, tartaric acid, IPMP (iso-propylmethoxypyrazine) and IBMP (iso-butyl-methoxypyrazine) were lower at equivalent °Brix in 4-cane compared with 2-cane berries. Significantly higher concentrations of quercetin were found in exposed compared to shaded berries. Must analysis showed a significant influence of crop load on berry titratable acidity and pH, reflecting berry ripening results. Exposure significantly increased the concentrations of nitrogenous compounds in 4-cane must yet showed no influence on 2-cane must. After wine processing lower malic acid concentrations in wines made from 100% exposed fruit became evident in lower wine titratable acidity but showed no influence on wine pH. Bentonite addition to wines had a small but statistically significant influence on wine by reducing pH, titratable acidity and alcohol. Bound sulphur concentrations were significantly higher in 4-cane versus 2-cane wines. At harvest, methoxypyrazine levels in grapes and wines were very low; IBMP concentrations where significantly lower than those normally found in Sauvignon blanc wines from Marlborough. This was attributed to the absence of basal leaves from the shoots of ripening berries. The results suggest that leaf area to fruit ratio is a powerful determinant of grape and wine quality.

In den letzten Jahren wurden relativ komplexe Erosionsmodelle entwickelt, deren Teilprozesse immer mehr auf physikalisch begründeten Ansätzen beruhen. Damit verbunden ist eine höhere Anzahl aktueller Eingangsparameter, deren Bestimmung im Feld arbeits- und kostenaufwendig ist. Zudem werden die Parameter punktuell, also an bestimmten Stellen und nicht flächenhaft wie bei der Fernerkundung, erfasst. <br /> <br /> Im Rahmen dieser Arbeit wird gezeigt, wie Satellitendaten als relativ kostengünstige Ergänzung oder Alternative zur konventionellen Parametererhebung genutzt werden können. Dazu werden beispielhaft der Blattflächenindex (LAI) und der Bedeckungsgrad für das physikalisch begründete Erosionsmodell EROSION 3D abgeleitet. Im Mittelpunkt des Interesses steht dabei das Aufzeigen von existierenden Methoden, die die Basis für eine operationelle Bereitstellung solcher Größen nicht nur für Erosions- sondern allgemein für Prozessmodelle darstellen. Als Untersuchungsgebiet dient das primär landwirtschaftlich genutzte Einzugsgebiet des Mehltheuer Baches, das sich im Sächsischen Lößgefilde befindet und für das Simulationsrechnungen mit konventionell erhobenen Eingangsparametern für 29 Niederschlagsereignisse im Jahr 1999 vorliegen [MICHAEL et al. 2000].<br /> <br /> Die Fernerkundungsdatengrundlage bilden Landsat-5-TM-Daten vom 13.03.1999, 30.04.1999 und 19.07.1999. Da die Vegetationsparameter für alle Niederschlagsereignisse vorliegen sollen, werden sie basierend auf der Entwicklung des LAI zeitlich interpoliert. Dazu erfolgt zunächst die Ableitung des LAI für alle vorhandenen Fruchtarten nach den semi-empirischen Modellen von CLEVERS [1986] und BARET & GUYOT [1991] mit aus der Literatur entnommenen Koeffizienten. Des Weiteren wird eine Methode untersucht, nach der die Koeffizienten für das Clevers-Modell aus den TM-Daten und einem vereinfachten Wachstumsmodell bestimmt werden. Der Bedeckungsgrad wird nach ROSS [1981] aus dem LAI ermittelt. Die zeitliche Interpolation des LAI wird durch die schlagbezogene Anpassung eines vereinfachten Wachstumsmodells umgesetzt, das dem hydrologischen Modell SWIM [KRYSANOVA et al. 1999] entstammt und in das durchschnittliche Tagestemperaturen eingehen. Mit den genannten Methoden bleiben abgestorbene Pflanzenteile unberücksichtigt. Im Vergleich zur konventionellen terrestrischen Parametererhebung ermöglichen sie eine differenziertere Abbildung räumlicher Variabilitäten und des zeitlichen Verlaufes der Vegetationsparameter.<br /> <br /> Die Simulationsrechnungen werden sowohl mit den direkten Bedeckungsgraden aus den TM-Daten (pixelbezogen) als auch mit den zeitlich interpolierten Bedeckungsgraden für alle Ereignisse (schlagbezogen) durchgeführt. Bei beiden Vorgehensweisen wird im Vergleich zur bisherigen Abschätzung eine Verbesserung der räumlichen Verteilung der Parameter und somit eine räumliche Umverteilung von Erosions- und Depositionsflächen erreicht. Für die im Untersuchungsgebiet vorliegende räumliche Heterogenität (z. B. Schlaggröße) bieten Landsat-TM-Daten eine ausreichend genaue räumliche Auflösung. Damit wird nachgewiesen, dass die satellitengestützte Fernerkundung im Rahmen dieser Untersuchungen sinnvoll einsetzbar ist. Für eine operationelle Bereitstellung der Parameter mit einem vertretbaren Aufwand ist es erforderlich, die Methoden weiter zu validieren und möglichst weitestgehend zu automatisieren. / Soil erosion models become increasingly more complex and contain physically based components, resulting in changing requirements for their input parameters. The spatial and temporal dynamics of erosions forcing parameters thus produce high requirements on data availability (costs and manpower). Due to this fact, the use of complex erosion models for extensive regions is strongly limited by the high in-situ expense. Moreover, conventional measurement procedures provide parameters at certain points, while remote sensing is a two-dimensional retrieval method.<br /> <br /> This thesis demonstrates, how satellite data can be used as a cost-effective supplementation or alternative to conventional measurement procedures. Leaf area index (LAI) and soil cover percentage are examplarily derived for the EROSION 3D physically based soil erosion model. The main objective of this study is to summarise existing retrieval methods in order to operationally provide such paramaters for soil erosion models or for process models in general. The methods are applied to a catchment in the loess region in Saxony (Germany), that predominantly is agriculturally used. For comparison, simulations based on conventionally estimated parameters for 29 rainstorm events are available [MICHAEL et al. 2000]. <br /> <br /> The remote sensing parameters are derived from Landsat 5 TM data on the following dates: 13.03.1999, 30.04.1999, 19.07.1999. To get temporally continuous data for all events, they are interpolated between the acquisition dates based on the LAI development. Therefore, LAI is firstly calculated for all occurring crops by means of the semi-empirical models of CLEVERS [1986] and BARET & GUYOT [1991]. The coefficients appropriated to these models are taken from literature. Furthermore, a method is investigated that enables coefficient estimation for the Clevers model from Landsat data combined with a simplified growth model. Next, soil cover percentage is derived from LAI after ROSS [1981]. The LAI interpolation is performed by the simplified crop growth model from the SWIM hydrological model [Krysanova et al. 1999]. It has to be mentioned, that plant residue remains unconsidered by the used methods. In comparison to conventional measurement procedures, these methods supply a differentiated mapping of the spatial variability and temporal behaviour regarding the vegetation parameters.<br /> <br /> The simulations with EROSION 3D are carried out for the remotely sensed soil cover percentages, that are retrieved in two ways. Soil cover is directly derived from the remote sensing data for each pixel at the acquisition dates as well as estimated by means of the interpolation for each field on all rainstorm events. In comparison to conventionally determined soil cover, both methods provide an improved spatial allocation of this parameter and thus, a spatial reallocation of erosion and deposition areas. The used Landsat Data provide an adequate spatial resolution suitable for the spatial heterogeneity given in the test area (e. g. field size). These results show that satellite based remote sensing can be reasonably used within the scope of these investigations. In the future, operational retrieval of such remotely sensed parameters necessitates the validation of the proposed methods and in general the automation of involved sub-processes to the greatest possible extent

Eddy-covariance (EC) CO₂ flux data were analysed and annual carbon (C) balances estimated for a four-year period (2004-2007) following clearcut harvesting of a boreal jack pine stand in northern Saskatchewan. The site was a source of C to the atmosphere for all years, with annual net ecosystem productivity (NEP) increasing from -153 g C m⁻² yr⁻¹ in 2004 to -63 g C m⁻² yr⁻¹ in 2007. This increase was mainly due to gross primary productivity (GPP) increasing significantly from 78 to 200 g C m⁻² yr⁻¹ , while ecosystem respiration (R) increased only slightly from 231 to 263 g C m⁻² yr⁻¹ over the same period. In the 2006 growing season (GS), a field campaign was conducted to investigate the relationships between monthly destructive measurements of leaf area index (LAI) and daily measurements of the normalized difference vegetation index (NDVI) and photosynthetic capacity (Amax). The latter was derived from 5-day, 16-day, 30-day and annual Michaelis-Menten light response analyses using daytime measurements of NEP and incident photosynthetically active radiation. Digital-camera data were used to evaluate the potential of using the rectilinear-lens vegetation index (RLVI) as a surrogate for NDVI of a young forest stand. Results showed that LAI was linearly related to NDVI and RLVI, which was largely the result of changes in the deciduous vegetation component across the GS. These results indicate that RLVI could be used as a surrogate for NDVI up to a GS maximum LAI of 0.91 m2 m⁻² observed in 2006. Measured mean (± 1 S.D.) GS LAI was 0.67 (± 0.24) m² m⁻² in 2006. LAI accounted for the majority of the variability in Amax at the 30-day time scale, while at shorter time scales air temperature was the dominant control. For 2004 to 2007, mean spring estimates of LAI were 0.25, 0.29, 0.38 (compared to 0.40 m² m⁻² from measurements) and 0.41 m² m⁻², respectively. Results suggest that a steady increase in the jack pine LAI component accounted for the annual increases in GPP and hence NEP over the four years.