Recuperação das trocas gasosas e fluorescência da clorofila em plantas de Annona emarginata (Schltdl.) H. Rainer submetidas a estrese hídrico

Pós-graduação em Ciências Biológicas (Botânica) - IBB

Potencial produtivo da cana-de-açúcar sob irrigação por gotejamento em função de variedades e ciclos

This study aimed to evaluate the yield potential of different varieties of sugarcane under drip irrigation in two growth cycles. A trial was set up in October 2006 at Jaú region (São Paulo state, Brazil), in an experimental field with a eutrophic Ultisol. The experiment was conducted in randomized complete blocks with factorial treatment structure 8 x 2, constituted by eight sugarcane varieties and two crop cycles, with six replicates. Stalk productivity (TCH), sugar productivity (TPH), juice quality traits and water use efficiency in relation to stalk productivity were evaluated in each crop cycle. It was observed that varieties of sugarcane respond differently to full irrigation, and this response is influenced by climatic conditions of the agricultural year. In this study, only the first evaluation cycle (plant cane) was decisive to differentiate the performance among the varieties. The varieties IAC91-1099, IACSP96-3060, RB855536, RB867515 and SP85-1115 showed higher agro-industrial yield potential and less consumption of water and can be recommended for the management of production under drip irrigation.

Respostas fisiológicas de genótipos de Eucalyptus grandis x E. urophylla à disponibilidade hídrica e adubação potássica

Conduziu-se este trabalho, com o objetivo de estudar as respostas fisiológicas de cinco genótipos de eucalipto à disponibilidade hídrica e adubação potássica. As mudas foram plantadas em vasos preenchidos com sete litros de um Neossolo Quartzarênico, com baixo teor natural de potássio (0,2 mmol c.dm-3 K), e submetidas a dois regimes de irrigação (RI1 - diário e RI2 - irrigação suspensa até o aparecimento de sintomas iniciais de murcha), sem (K0) e com suprimento de potássio (K1 - 200 mg.dm-3 K2O), em casa de vegetação. Avaliou-se a taxa fotossintética (A), condutância estomática (gs), transpiração (E), índice de conteúdo de clorofila (ICC), conteúdo relativo de água (CRA), eficiência fotoquímica (Fv/Fm), eficiência intrínseca (EUAintr) e instantânea no uso da água (EUAinst) e potencial hídrico foliar (Ψf). O experimento foi estabelecido no delineamento de blocos ao acaso, em esquema fatorial 5 x 2 x 2 (5 genótipos, 2 regimes de irrigação e 2 níveis de adubação potássica), com cinco repetições. À exceção da eficiência fotoquímica, as demais características apresentaram alterações significativas no regime RI2, com redução nos valores de A, gs e E e aumento em ICC e EUAinst. O suprimento de potássio nas plantas do RI2 proporcionou maiores valores de A, gs, E e CRA. Dos genótipos avaliados, o G1 é o mais resistente e o G2 o mais sensível à deficiência hídrica. Conclui-se que a adubação potássica pode amenizar os efeitos negativos da deficiência hídrica nos estádios iniciais de crescimento de eucalipto.

Eficiência do silicato de potássio no controle do oídio e no desenvolvimento de abobrinha de moita

The most widely standard used for powdery mildew control on cucurbitaceas is the use of resistant cultivars and systemic fungicides, even though nutrition has been an option. The supply of silicon is benefic to many vegetable species, stimulating growth, yield, photosynthesis and regulation of transpiration; besides, its deposition in the epidermis avoids the invasion of fungus, bacteria and sucking insects. The aim of this experiment was to evaluate the influence of potassium silicate on powdery mildew control, development and yield of zucchini squash, cultivar Caserta. The experiment was conducted at Universidade Estadual Paulista, in greenhouse conditions and with a randomized design, divided in four replications, 11 plants per plot and five treatments: control (water), chemical treatment with fenarimol (2.4 g a.i. 100 L-1) and potassium silicate, in doses 1.5 L ha-1; 2.0 L ha-1 and 2.5 L ha-1. We evaluated the disease severity; gas exchange (net CO2 assimilation rates, transpiration, stomatal conductance and water use efficiency); growth (leaf area ratio, relative growth rate, absolute growth rate, net assimilation rate and specific leaf mass) and yield. The results showed that the foliar application of potassium silicate and fenarimol controlled powdery mildew and had no influence on plant growth. Therefore, the potassium silicate may be used as alternative for control of fungal pathogens and reduced application of chemical products, which provides a greater environmental sustainability. However, it is necessary to be careful with high doses because it was observed that 2.5 L h-1 was harmful to fruit production and gas exchange, despite being effective in controlling powdery mildew. According to this study it is recommended using 2.0 L ha-1 for control of powdery mildew to zucchini squash, and can replace the use of fenarimol, without affecting productivity and development of plants.

Estimativa da necessidade de nitrogênio em cobertura no feijoeiro IAC Alvorada com clorofilômetro portátil

The aims of this study was evaluated the efficiency of nitrogen sufficiency index (NSI) calculated with base on the measures relative chlorophyll index (RCI) leaves, measured with portable chlorophyll meter, as an indicator of time of sidedressing N fertilization and verify which value of NSI (90% and 95%) is the most appropriate to indicate the moment of N fertilization on common bean cultivar IAC Alvorada. An experiment with five N managements (M1: 200 kg ha(-1) N (40 kg at sowing + 80 kg at 15 days after emergency (DAE) + 80 kg 30 DAE); M2: 100 kg ha(-1) N (20 kg at sowing + 40 kg at 15 DAE + 40 kg at 30 DAE); M3: 20 kg ha(-1) N at sowing + 30 kg ha(-1) when chlorophyll meter readings indicated NSI < 95%; M4: 20 kg ha(-1) N at sowing + 30 kg N ha(-1) N when chlorophyll meter readings indicated NSI <90% and, M5: control (without N application)) and four replications was carried out in the rainy and dry growing seasons of the agricultural year 2009/10, in Botucatu, Sao Paulo State, Brazil. The variables RCI, aboveground dry matter, leaf N concentration, yield components, grain yield, and N use efficiency were evaluated. The NSI of 90%, calculated based on monitoring of RCI in common bean leaves with chlorophyll meter, was more effective than 95% to define need for N sidedressing in common bean cultivar IAC Alvorada, reducing the N application and improving the use efficiency of applied N.

Do litter manipulations affect leaf functional traits of savanna woody plants?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nitrogen fertilization (15NH4NO3) of palisadegrass and residual effect on subsequent no-tillage corn

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Overexpression of the activated form of the AtAREB1 gene (AtAREB1 Delta QT) improves soybean responses to water deficit

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produtividade, qualidade do fruto e desenvolvimento radicular do abacaxizeiro irrigado por gotejamento

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Transpiração e eficiência de uso da água em plantios puros e mistos de eucalyptus grandis e acacia mangium

Pós-graduação em Ciência Florestal - FCA

Doses de potássio e umidades de solo para o crescimento de plantas de mogno-africano

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Relação da tolerância ao déficit hídrico com o teor e acúmulo de nitrogênio, fósforo e potássio em cultivares de cana-de-açúcar

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Desempenho produtivo e econômico do consórcio de cafeeiro arábica e nogueira-macadâmia

The objective of this work was to evaluate the productive and economic performance of Arabica coffee and macadamia nut intercropping, under rainfed and drip-irrigation conditions, as well as the financial viability of treatments in three coffee price scenarios. A completely randomized design was used, with six treatments (rainfed sole coffee, irrigated sole coffee, rainfed coffee-macadamia nut intercropping, irrigated coffee-macadamia nut intercropping, rainfed sole macadamia nut, and irrigated sole macadamia nut) and ten replicates. The productivity, the area equivalency index, and the economic outcomes of the treatments were evaluated in three coffee price scenarios. Drip irrigation and intercropping increased coffee and macadamia nut yields, in comparison to rainfed monocultures, and generally promoted the same productivity as the coffee irrigated monocultures, as well as higher productivity than the macadamia nut irrigated monocultures. The combined use of intercropping and drip irrigation promotes land-use efficiency 5-fold greater than the averages of rainfed monocultures. Irrigated intercropping promotes higher profitability and faster return on investment, making it a viable alternative, especially in periods of lower coffee prices.

Performance measurement and indicators for water supply management: review and international cases

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho e uso eficiente da terra de modalidades de consorciação com milho e forrageiras

This study was developed with the aim of evaluating the performance and land use efficiency of different arrangements of intercropping with maize and forage. The field experiment was conducted in Tangar da Serra/MT. The experimental design was a randomized block in factorial scheme 3x2 + 1, were as three arrangements of intercropping, two species of forage and an additional treatment with maize monoculture in four replication. In maize monoculture and intercropping were evaluated: plant height and ear insertion height, plant population, weight of 100 grains, productivity, number of grain rows and number of grain per row. In forages intercropping with maize were evaluated plant population and dry matter accumulation. The arrangements with Maize + Forage sown in the line and Maize + Forage sown in two rows between rows with the species Urochloa hybrid promoted best corn yields. The modality and species affect both the productivity of maize as forages species. Grain yield of maize is higher in monoculture. The higher dry matter accumulation of Urochloa hybrid occurs in the Maize + Forage sown in one row between rows, while, for the Urochloa brizantha the arrangements studied do not affect their yields. The arrangement with best land use efficiency is Maize + Forage sown in two rows between rows for both study forage species.