Controle biológico da podridão radicular (Pythium aphanidermatum) e promoção de crescimento por Pseudomonas chlororaphis 63-28 e Bacillus subtilis GB03 em alface hidropônica

Podridões radiculares causadas por espécies de Pythium são um importante problema em cultivos hidropônicos. Sintomas de subdesenvolvimento são observados nas plantas parasitadas pelo patógeno, sendo muitas vezes não diagnosticados pelo produtor. O objetivo do trabalho foi avaliar o controle biológico da podridão radicular causada por Pythium aphanidermatum e a promoção de crescimento por Pseudomonas chlororaphis 63-28 e Bacillus subtilis GB03, reconhecidos agentes de controle biológico de doenças de plantas. A inoculação das plantas com P. aphanidermatum ocasionou o subdesenvolvimento, sendo essa diminuição de 20%. A adição dos agentes de biocontrole na solução nutritiva teve um efeito positivo no aumento da massa (6% a 13%), no número de folhas (4% a 7%) e no teor de clorofila (3%) das plantas de alface. Entretanto, maiores estudos devem ser realizados para melhorar a capacidade de controle da doença e de promoção de crescimento pelos agentes de biocontrole estudados no cultivo de alface hidropônica.

Alelopatia de extratos aquosos de canela-sassafrás (Ocotea odorifera (Vell.) Rohwer)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Growth and physiological responses of sunflower plants exposed to ultraviolet-B radiation

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

Adubação foliar com silício na cultura do milho

Inúmeros trabalhos têm demonstrado o efeito benéfico da adubação com silício sobre o acréscimo da produção de diversas culturas, como, por exemplo, arroz, cana-de-açúcar e batata. No entanto, são escassas as informações sobre os benefícios nutricionais do silício para a cultura do milho. Desta maneira, objetivou-se, neste estudo, avaliar o efeito de doses e épocas de aplicação de silício, via foliar, nas características agronômicas e na produtividade do milho, cultivado no ano agrícola 2007/2008. O delineamento experimental adotado foi o de blocos casualizados, em esquema fatorial (4 x 3) + 1, com quatro repetições, envolvendo doses de silício (130, 260, 390 e 520 g ha-1 de Si) aplicadas via foliar, épocas de aplicação (2, 5 e 8 folhas expandidas) e uma testemunha (sem aplicação de Si). As variáveis analisadas foram altura das plantas e a inserção da primeira espiga, diâmetro de colmo, índice de clorofila foliar, teor foliar de silício, número de grãos por espiga, massa de 100 grãos e produtividade de grãos. O silício aplicado via foliar influenciou somente o teor foliar de Si.

Tolerância de diferentes cultivares de cana-de-açúcar (Saccharum spp.) a herbicidas

This work aimed to evaluate the tolerance of sugarcane cultivars to sulfentrazone, imazapic, isoxaflutole, clomazone and ametryn + trifloxysulfuron-sodium. The experiment was arranged in a randomized block design in a split-plot scheme. The cultivars were allocated to the plots and the herbicides to the sub-plots (five 8.0 m long rows and 1.5 m spacing, with 4 repetitions. The herbicides sulfentrazone (0.8 kg ha(-1)), imazapic (0.147 kg ha(-1)), isoxaflutole (0.1125 kg ha(-1)), clomazone (1.1 kg ha(-1)), ametryn (1.463 kg ha(-1)) + trifloxysulfuron sodium (0.037 kg ha-1) and control were evaluated on 3-yr-old ratoons of the cultivars IACSP94-2094, IACSP94-2101, IACSP93-3046, IACSP94-4004, IAC86-2480 and RB72454 in post emergence. The traits evaluated were: plant toxicity symptoms in the plant leaves; total chlorophyll content and photochemical efficiency (Fv/Fm) at 15, 30 and 60 days after application (DAA); height (cm) at 30 and 270 DAA, and plant stand (stalk m(-1)) at 30 and 180 DAA. Diameter (cm), estimated productivity (t ha(-1)) and quality analysis were evaluated at 270 DAA. The sugarcane cultivars IACSP94-2094, IACSP93-3046, IACSP94-4004, IAC86-2480, RB72454, and IACSP94-2101 especially, were susceptible to clomazone up to 30 DAA, due to leaf chlorosis and lower chlorophyll content, but had no effect on quality characteristics and productivity. The cultivars were also tolerant to other herbicides.

Effect of different tannery sludge compost amendment rates on growth, biomass accumulation and yield responses of Capsicum plants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phenology of a dioecious population of Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in a stream from southeastern Brazil

The seasonal dynamics of a dioecious population of Batrachospermum delicatulum (Skuja) Necchi and Entwisle was evaluated biweekly during the growth period of the macroscopic gametophyte, from late autumn (May) to early spring (October) in a third-order stream from the northeast region of Sao Paulo State, southeastern Brazil (20°43'S, 49°13'W). The population fluctuated throughout the study period in terms of percentage cover, frequency and chlorophyll content. Percent cover and frequency showed a clear pattern with the lowest values at the initial and final stages of the growth period and the highest in July-August (winter). Gametophyte growth was associated with high illumination and low temperature, which agrees with most observations on Batrachospermales in stream environments. Relatively wide variations in reproductive characteristics were observed during the growth period, which were not correlated with percentage cover, frequency and chlorophyll content. The phenologic pattern observed in this population was characterized by a synchronic development of female/male plant ratio with the number of spermatangia per plant resulting in. (i) a higher proportion of fertilized (carposporophytic) plants associated with more male plants; (ii) higher fertilization rates during the periods with higher production of spermatangia per plant; and (iii) higher production of spermatangia per plant when the population had more male plants. These characteristics were largely associated with water temperature and ion content. In terms of reproductive success, the population studied can be regarded as highly efficient, considering the relatively low proportion of male to female plants and high fertilization rates. These data are consistent with a hypothesis to explain high fertilization rates in dioecious species in lotic habitats consisting of outcrossing among adjacent plants with intermingled male and female branches within an algal cluster. Efficient reproductive strategies have been reported in dioecious, monoecious and even mixed populations of B. delicatulum and can be interpreted as adaptations to successfully colonize streams with different characteristics.

Uso de biossólido como substrate para produção de mudas de eucalipto

The objective of this study was to evaluate the feasibility of the biosolids used as substrate component for seedlings production of Eucalyptus. This way, different proportions of biosolid/carbonized rice (80/20, 70/30, 60/40, 50/05 and 40/60) were tested as substrates in mixture, which were compared to the common substrate used by forest nursery (Multiplant®), as control. The experiment was established with Eucalyptus grandis where growth seedlings-related parameters were assessed: shoot height, collar diameter, accumulation of dry matter on the shoot and root, chemical analysis of the vegetal tissue of aerial part and root, foliar area and chlorophyll content. The results revealed that Eucalypts seedlings developed in substrate with 50% biosolid were similar to the control in relation to the evaluated parameters, concluding that the use of biosolids for seedlings production is quite promising.

Effect of the density and of the distance of Brachiaria decumbens staff on the initial growth of Coffea arabica L. Seedligns

The aim of this work was to evaluate the interference of three densities (4, 8 and 16 plants/m 2) of Brachiaria decumbens Stapf distributed at three different distances (0, 10 and 20 cm from coffee plants) on the initial growth of Coffea arabica L. seedlings. Dark red Latosoil was used as substrate to fill up 70 liters cement boxes. Coffee seedlings at 15 cm height and 8 leaves stage were planted in each box. B. decumbens seedlings were transplanted when they reached two to four leaves stage. The experimental design was a randomized blocks with ten treatments and three replications. At the end of the experiment were measured, height, leaf number, leaf area, chlorophyll content and dry weight of coffee plants. Dry weight of B. decumbens leaves was also evaluated. The leaf area and leaf dry weight was shown to be more sensitive parameters to the interference of Brachiaria plants. Dry weight of coffee plants were reduced from 60% to 88% when the B. decumbens were transplanted 0 cm from the coffee plant. With distance of 10 cm the reduction of dry weight increased with the increase of the density of the B. decumbens. In the coexistence of the coffee plants with 16 plants/m 2 of B. decumbens, there was a reduction in the dry weight of about 80% at the distances of 0 and 20 cm. Regarding leaf area, the reduction was 47% on the average in the density of 4 plants/m 2 of B. decumbens The reduction in leaf area at other densities was higher at the distance of 0 and 20 cm, and 55% reduction was obtained at the distance of 10 cm.

Avaliação dos teores nutricionais em laranjeira 'Valência', sob fertirrigação

This work aimed to compare fertigation to conventional fertilization in a five-year-old 'Valência' orange orchard, irrigated by microsprinklers. The conventional fertilization, using the recommended dosage for the crop, was parceled out in three during the year. In the fertigation treatments a complete dose, 1/2 and 1/3 of the conventional fertilization dose, parceled out in ten in a year, were used. Trunk circumference and leaf volume, leaf chlorophyll content and fruit yield and quality were measured. For the first year, significant differences among the treatments for the evaluated parameters were not observed; however, it was noticed that fertigation treatments caused less nutritional unbalance, obtained by DRIS. The fertigation treatment using half dosage showed the best result regarding to fruit yield and quality.

Use of Physiological Parameters in Screening Drought Tolerance in Sugarcane Genotypes

The physiological response of four commercial sugarcane genotypes to water stress was evaluated by measuring the photochemical efficiency of the photosystem II (chlorophyll a fluorescence ratio, F v/F m), estimated chlorophyll content (SPAD unit), leaf temperature (LT) and leaf relative water content (RWC). A field trial was established in the subtropical area with well-watered and water-stressed genotypes, in completely randomized blocks with four replicates in a 4 × 2 × 3 factorial design (genotype × irrigation × evaluation date). Physiological measurements were done during a 90 day-period of formative stage of plants. The analysis of variance showed that the interaction of genotype × irrigation × evaluation date had a significant effect for three physiological markers tested, F v/F m, SPAD unit and RWC. Under non-stressed conditions, all genotypes showed similar responses for the four markers. Under water deficiency stress, two drought-tolerant genotypes, HOCP01-523 and TCP89-3505 displayed higher values for F v/F m, SPAD unit and RWC, and lower values for LT, and could be classified as tolerant. It is therefore possible to use these physiological water stress associated traits as scorable marker traits for selecting drought-tolerant sugarcane genotypes in future breeding programs. © 2011 Society for Sugar Research & Promotion.

Efeito da densidade de semeadura e de reguladores vegetais sobre os caracteres morfofisiológicos da folha bandeira do trigo

The objective of this work was to study the morphological and physiological characteristics of the wheat flag leaf as affected by increasing sowing densities and plant growth regulators application. The experimental design was a split-plot with completely randomized blocks and four replications. Plots were consisted by four sowing densities (30, 50 70 and 90 plants m-1) and the split-plots by plant growth regulators: a product composed by auxin+gebberellin+cytokinin (Ax+GA+CK), Trinexapac-Ethyl e (Ax+GA+CK) + Trinexapac-Ethyl, and a control without application. Dry mass accumulation, plant height, morphological characteristics, SPAD index, nitrogen and photosynthetic pigments contents in the flag leaf were determined. The increase in the sowing density resulted in lower dry mass accumulation and SPAD index of the flag leaves. Trinexapac-Ethyl caused increase in the SPAD index, but the chlorophyll content of the flag leaf was reduced. The SPAD index values were more correlated with the nitrogen than the chlorophyll contents. Ax+GA+CK did not affect flag leaf characteristics in wheat plants.

Crescimento e desordem nutricional em pimenteira malagueta cultivada em soluções nutritivas suprimidas de macronutrientes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Níveis de fertirrigação na avaliação das características morfofisiológicas em mudas de pimenta malagueta

O presente trabalho teve o objetivo de avaliar as características morfofisiológicas de mudas de pimenta malagueta (Capsicum frutescens) sob diferentes níveis de fertirrigação, utilizando-se fertilizante líquido 10-10-10 (N-P-K). O experimento foi realizado na Faculdade de Ciências Agrárias da Universidade Federal da Grande Dourados. O delineamento experimental foi em blocos casualizados (DBC), com seis doses de fertilizante líquido (0; 2,5; 5,0; 10,0; 20,0 e 40 mL L-1) diluídos na água de irrigação e quatro repetições. As mudas foram produzidas em viveiro telado, em bandejas de 128 células preenchidas com substrato. Realizou-se uma fertirrigação, aos 15 dias após a semeadura ( DAS). Avaliou-se, aos 30 dias após a semeadura, o número de folhas, o comprimento da parte aérea e da raiz, a massa fresca e seca da parte aérea e da raiz, a área foliar e o teor de clorofila. A dose de 25 mL L-1 do fertilizante líquido 10-10-10, aplicada via fertirrigação, é recomendada para a produção de mudas de pimenta malagueta, embora tenha havido aumento da massa seca de raízes e parte aérea em dose maior.

Morfofisiologia da cunhã cultivada sob estresse salino

The experiment was developed based on the importance of the nutritional factor cunhã for large and small, animals and on the growth of this forage in typical soils of the semiarid region, generally with salinity from natural or anthropogenic action. The experiment was performed in vessels with a capacity of 5kg prepared in a protected environment with full sunshine in the Department of Technology and Social Sciences (DTCS) of UNEB Campus III in Juazeiro - BA. It evaluated the effect of seven different salt concentrations on increasing levels of irrigation water electrical conductivity - ECw (0, 2, 4, 6, 8, 10 and 12 dS/m), at room temperature. The analysis of culture were taken every seven days observing the number of leaves, stem diameter, plant, plant length and total chlorophyll content at 13; 20; 27; 34 and 40 days after the start of irrigation with saline. The contents of proline, the ratio aero part/Root (AP/Rt), the root length and water content were evaluated in the 40 th day after the onset of treatment. The results showed that the elevation of ECw affected all variables.