Mycorrhizal dependency of mangaba tree under increasing phosphorus levels

The objective of this study was to evaluate the mycorrhizal dependency of mangaba tree (Hancornia speciosa) plantlets, under increasing levels of phosphorus fertilization. The experimental design was completely randomized in a 4×5 factorial arrangement with three mycorrhizal fungi inocula - Gigaspora margarita, Glomus etunicatum, or a pool of native mycorrhizal fungi (Acaulospora longula, Glomus clarum, Gigaspora albida, Paraglomus sp.) -, and a nonmycorrhizal control, in combination with five levels of phosphorus applied to the substrate: 0, 25, 50, 75, and 100 mg kg-1. After 180 days of growth, plantlets with inoculation of native mycorrhizal pool produced more shoot and root dry biomass and had higher shoot phosphorus content and accumulation. The noninoculated control showed the lowest values, independently of the phosphorus level. The highest relative mycorrhizal dependency occurred with the inoculation of native mycorrhizal fungi. Plants with mycorrhizal fungi did not respond to phosphorus addition above 50 mg kg-1. Mangaba tree is highly dependent on mycorrhiza, but the degree of dependency varies according to phosphorus levels and fungal inocula. In general, mangaba tree is more responsive to mycorrhizal fungi inoculation than to phosphorus addition.

Desempenho de clones de copa de seringueira resistentes ao mal-das-folhas

O objetivo deste trabalho foi avaliar o desempenho de 18 clones de seringueira resistentes ao Microcyclus ulei, usados como copas enxertadas. Foram utilizados oito clones híbridos de Hevea pauciflora x Hevea guianensis var. marginata, oito de H. pauciflora x H. rigidifolia e dois clones de H. pauciflora, enxertados sobre o painel de CNS AM 7905 - seleção primária de H. brasiliensis - e cultivados em Latossolo Amarelo distrófico, em Manaus, AM. Foram avaliados: perímetro do tronco, estado nutricional e produtividade de borracha seca. Copas enxertadas de híbridos H. pauciflora x H. guianensis var. marginata causam crescimento mais rápido do tronco, com redução do período de imaturidade da seringueira. O alto nível de resistência dos híbridos de H. rigidifolia ao percevejo-de-renda (Leptopharsa heveae) justifica a introdução de outros genótipos dessa espécie para novas hibridações. Os clones CPAA C 01, 06, 13, 15, 16 e 45 apresentam excelente potencial de produção de borracha seca, nas condições climáticas e de solos de terra firme da Amazônia Tropical Úmida.

Tropical terrestrial model ecosystems for evaluation of soil fauna and leaf litter quality effects on litter consumption, soil microbial biomass and plant growth

The aim of this work was to evaluate whether terrestrial model ecosystems (TMEs) are a useful tool for the study of the effects of litter quality, soil invertebrates and mineral fertilizer on litter decomposition and plant growth under controlled conditions in the tropics. Forty-eight intact soil cores (17.5-cm diameter, 30-cm length) were taken out from an abandoned rubber plantation on Ferralsol soil (Latossolo Amarelo) in Central Amazonia, Brazil, and kept at 28ºC in the laboratory during four months. Leaf litter of either Hevea pauciflora (rubber tree), Flemingia macrophylla (a shrubby legume) or Brachiaria decumbens (a pasture grass) was put on top of each TME. Five specimens of either Pontoscolex corethrurus or Eisenia fetida (earthworms), Porcellionides pruinosus or Circoniscus ornatus (woodlice), and Trigoniulus corallinus (millipedes) were then added to the TMEs. Leaf litter type significantly affected litter consumption, soil microbial biomass and nitrate concentration in the leachate of all TMEs, but had no measurable effect on the shoot biomass of rice seedlings planted in top soil taken from the TMEs. Feeding rates measured with bait lamina were significantly higher in TMEs with the earthworm P. corethrurus and the woodlouse C. ornatus. TMEs are an appropriate tool to assess trophic interactions in tropical soil ecossistems under controlled laboratory conditions.

Lysine and arginine requirements of Salminus brasiliensis

The objective of this work was to determine the dietary lysine (DL) and dietary arginine (DA) requirements of dourado (Salminus brasiliensis), through dose-response trials using the amino acid profiles of whole carcasses as a reference. Two experiments were carried out in a completely randomized design (n=4). In the first experiment, groups of 12 feed-conditioned dourado juveniles (11.4±0.2 g) were stocked in 60 L cages placed in 300 L plastic indoor tanks in a closed circulation system. Fish were fed for 60 days on diets containing 1.0, 1.5, 2.0, 2.5, 3.0, or 3.5 % dietary lysine. In the second experiment, dourado juveniles (27.0±0.8 g) were fed for 60 days on semipurified diets containing arginine at 1.0, 1.5, 2.0, 2.5 or 3.0%, in similar conditions to those of the first experiment. Optimal DL requirements, as determined by broken-line analysis method for final weight, weight gain and specific growth rate, were 2.15% DL or 5% lysine in dietary protein, and 1.48% DA or 3.43% arginine in dietary protein. The best feed conversion ratio is attained with 2.5% DL or 5.8% lysine in dietary protein and 1.4% DA or 3.25% arginine in dietary protein.

Identification and characterization of pathogenic Pestalotiopsis species to pecan tree in Brazil

The objective of this work was to characterize and cluster isolates of Pestalotiopsis species and to identify those that are pathogenic to pecan, based on morphological and molecular characters. Pestalotiopsis spp. isolates were identified by sequencing the internal transcribed spacer (ITS) and β?tubulin regions. Identification methods were compared to indicate the key morphological characters for species characterization. Thirteen isolates were used for the pathogenicity tests. Morphological characterization was performed using the following variables: mycelial growth rate, sporulation, colony pigmentation, and conidial length and width. Ten pathogenic isolates were identified, three as -tubulin regions. Identification methods were compared to indicate the key morphological characters for species characterization. Thirteen isolates were used for the pathogenicity tests. Morphological characterization was performed using the following variables: mycelial growth rate, sporulation, colony pigmentation, and conidial length and width. Ten pathogenic isolates were identified, three as Pestalotiopsis clavispora and three as P. cocculi. The other isolates remained as an undefined species. The morphological characters were efficient for an initial separation of the isolates, which were grouped according to differences at species level, mainly colony diameter, which was identified as an important morphological describer. Beta-tubulin gene sequencing was less informative than the ITS region sequencing for species identification.

EFFECTS OF THIDIAZURON (TDZ) ON FRUITING OF TEMPERATE TREE FRUITS

Thidiazuron (TDZ) is a phenylurea like citokinin on cell division fruit growth and fruit shape in some deciduous fruit trees. The effects of TDZ applied during flowering on apple cultivars 'Gala' and 'Fuji" were evaluated during seven growing seasons with annual applications on the same trees. The effects on pear and kiwi fruit trees were also evaluated. Every year, TDZ significantly increased fruit set and fruit weight on apple trees. The seven-year average of the fruit set from TDZ at 10 mg.L-1 was 112.7% while the control was only 51.3%. TDZ did not affect the number of clusters. The fruit weight increased 7.0% and 18.3% when the trees were sprayed with TDZ at 10 mg.L-1 and 5 mg.L-1, respectively. TDZ also increased fruit yield per tree by 28.7% and 41.8% for the 10 mg.L-1 and 5 mg.L-1 treatments, respectively. TDZ reduced the seed number per fruit and the calcium content in the flesh fruit, but increased the fruit firmness. The fruit set increased significantly on pear cultivar Packm's Triumph treated with TDZ, and reduced the seed numbers per fruit. TDZ applied at 12.5 mg.L-1 increased fruit weight by 47,4% on "Monty" kiwi.

Influence of the temperature in germination of seeds of jabuticaba tree

The jaboticaba tree (Myrciaria spp.) is originated from the center-south of Brazil and presents different types. It's a medium size tree, with tendency to form a crown with great number of branches. A characteristic considered as limitant for the commercial crop is the great juvenility, advicing producing good rootstocks of seedlings and graft wanted varieties, and other vegetative processes. With the purpose of evaluating the effect of temperature on germination of three clones of jaboticaba tree, was carried out a laboratorial research. It was observed influence of the temperature on germination. The highest percentage of germination was obtained at low temperature (15ºC and 20ºC). When it was used the temperature of 35ºC, two clones had only 8% of germination, while the other one was verified 35%. These values show the possibility of the ocurrence of variability among the clones of jaboticaba tree.

Gas exchange of the umbu tree under semi-arid conditions

A study was carried out at Embrapa Semi-Árido, Petrolina-PE, Brazil, aiming to understand the gas exchange process of the umbu tree (Spondias tuberosa Arr. Cam.) in the dry and rainy seasons. Stomatal conductance, transpiration, photosynthesis and internal CO2 concentration were obtained with a portable infrared gas analyzer (IRGA). During the dry season the umbu tree showed a much lower stomatal conductance early in the morning, as soon as the vapor pressure deficit increased, apparently affecting CO2 assimilation more than transpiration. The highest values were detected around 6:00 am but decreased to the lowest points between 10:00 am and 2:00 pm. During the rainy season, however, stomatal conductance, transpiration and photosynthesis were significantly higher, reaching the highest values between 8:00 and 10:00 am and the lowest around 2:00 pm. It was also observed at 4:00 pm, mainly during the rainy season, an increase on these variables indicating that the umbu tree exhibits a two-picked daily course of gas exchange.

Peduncle and fruit yield, in six cropping seasons, of early dwarf cashew tree clones irrigated with different water regimes

The objective of this work was to evaluate peduncle and fruit yield in clone MS 076 and in a clonal population of drip-irrigated, early dwarf cashew trees propagated by layering, in six cropping seasons. In order to meet the increased water requirements of the crop resulting from plant growth and development, irrigation during the dry season was performed daily according to the following water regime: 15 min/plant/day during the 1st year, 30 min/plant/day during the 2nd year, 45 min/plant/day during the 3rd year and 60 min/plant/day during all subsequent years. Water was supplied by one drip emitter/plant, at an (adjustable) flow rate of 36 L/h.The research was carried out in Fortaleza-Ceará, Brazil, and a random block design was utilized, with five replicates and split-plots. The clones were assigned to plots and the cropping seasons were considered as subplots. The clonal population was superior to the clone only with regard to number of nut shells (NNS), and solely in the first season. The clone was superior to the population as to NNS and peduncle yield (PY) in the second season, and also with regard to the three evaluated traits - NNS, PY, and nut shell yield, in the last three cropping seasons.

Leaf area estimatites of custard apple tree progenies

Leaf area measurements are required in several agronomical studies. Usually, there is an interest for measurement methods that are simple, quick and that will not destroy the leaf. The objectives of this work were to evaluate leaf area (y), length (l) and width (w) of 20 half-sibling progenies of custard apple tree (Annona squamosa L.), and to fit regression equations of the type y = a + bx, where x = l.w, that will allow y to be estimated based on l and w. The experiment was conducted as random blocks with five replicates and four plants per plot. Five mature leaves were randomly collected from each plant. Leaf area was measured with an automatic measuring device and leaf dimensions were determined with a ruler. All values of b were different from zero. Differences occurred only in 11% of the 190 possible comparison pairs between progenies, with regard to the estimates of b. No differences were observed between progenies with respect to leaf length, width and area. In view of this fact, the equation y = 0.72 x (R² = 0.77) was fitted for all progenies.

Estaquia do porta-enxerto de videira '43-43' (V. vinifera x V. rotundifolia) resistente à Eurhizococchus brasiliensis

O experimento foi realizado com o objetivo de avaliar a propagação vegetativa por estaquia do porta-enxerto de videira '43-43'. Ramos herbáceos coletados em janeiro e semilenhosos em março que foram separados em dois lotes: um de estacas retiradas do ápice e outro da base dos ramos. As estacas foram então imersas por 10 segundos em soluções contendo diferentes concentrações de ácido indolilbutírico (0; 1.000; 1.500; 2.000; 2.500 ou 3.000 mg.L-1), totalizando 12 tratamentos para cada época de enraizamento. Posteriormente, as estacas foram plantadas em vasos de polipropileno com areia e mantidas em casa de vegetação sob sistema de nebulização. Sessenta dias após o plantio das estacas, para cada época, foram avaliadas as seguintes variáveis: porcentagem de estacas enraizadas, comprimento médio de raízes, massa fresca de raízes e porcentagem de estacas brotadas. Estacas herbáceas e semilenhosas apresentaram alta porcentagem de enraizamento (66,0% e 68,0%, respectivamente) mesmo quando não tratadas com o fitorregulador. Estacas apicais apresentaram maior comprimento e massa fresca de raízes. A aplicação de AIB reduziu a porcentagem de enraizamento e de brotação de estacas herbáceas e semilenhosas. Estacas semilenhosas, quando tratadas com o AIB a 1.000 mgL-1, apresentaram maior comprimento e massa fresca de raízes.

Micropropagação de porta-enxertos híbridos de Vitis labrusca x Vitis rotundifolia com resistência à pérola-da-terra (Eurhizococcus brasiliensis Hempel, Hemiptera: Margarodidae)

A produção homogênea de porta-enxertos resistentes à pérola-da-terra (Eurhizococcus brasiliensis Hempel, Hemiptera: Margarodidae) e adaptados à região vitivinícola do Sul do País, pela técnica de micropropagação, poderá vir a atender à demanda do setor produtivo de uva e evitar as perdas causadas pela praga. O objetivo deste trabalho foi desenvolver um protocolo de micropropagação dos híbridos 1 e 2, que possuem as qualidades genéticas e de vigor desejadas para porta-enxerto, e resistência à pérola-da-terra. A partir de gemas axilares cultivadas em meio Galzy adicionado de 3µM de bezilaminopurina (BAP), foi possível induzir a multibrotação, com um número satisfatório de brotos, passível de ser incrementado por subcultivos sucessivos no mesmo meio de cultura. Os brotos obtidos neste meio e transferidos para o meio de cultura Galzy, adicionado de 8µM.10-3 de ácido naftalenoacético (ANA), enraizaram em 100%, superando a dificuldade de enraizamento que em geral tem sido a maior barreira apresentada pela espécie V. rotundifolia e seus híbridos.

Effect of humic substances and weather conditions on leaf biochemical changes of fertigated guava tree, during orchard establishment

In São Francisco Valley, Northeast Brazil, humic substances have been used by growers in fertigated fruit crops, due to its improvements on soil conditions and in plant nutrient uptake, metabolism and growth, reported from different growing places and crops. Nevertheless, little information about plant response to humic substance usage for local soil, weather and cropping system conditions is known. Hence, the metabolic response of guava tree during the orchard establishment to fertigation with humic substances and its correlation to the weather conditions were evaluated in Petrolina, State of Pernambuco. The treatments were manure application in soil combined with mineral fertilizers and humic substances applied through water of irrigation. The results showed that the fertigation treatments and plant age did not present conclusive effects in guava leaf contents of carbohydrates, proteins and amino acids. On the other side, the leaf contents of these compounds were influenced by the weather conditions.

Diversity and genetic struture in cajá tree (spondias mombin l.) populations in northeastern Brazil

Spondias mombin L. is a fruit tree from the American continent from the Anacardiaceae family. In Brazil it is common in different vegetation types but is more frequent in the Atlantic and Amazonian rainforests. It is economically important because of its fruits, which are widely consumed raw or processed as fruit jellies, juices and ice creams. The leaves have great importance in the pharmaceutical industry because of their antibacterial properties. In the state of Pernambuco, cajá tree is widely distributed in the Zona da Mata region and less frequently in the Agreste and Sertão areas. In this work diversity and genetic structure were studied in four populations of cajá tree from Pernambuco's Zona da Mata, Northeast Brazil, using isozymes polymorphism analyses from electrophoreses. The result showed 100% of polymorphism (P) for nine alleles and the average of alleles per locus s was 2.4. The expected heterozygosity ranged from 0.530 to 0.574 and the observed heterozygosity , from 0.572 to 0.735. It was not observed inbreeding and the average F IT was -0.175, whereas within population inbreeding (f) varied from -0.08 to- 0.37. The genetic divergence among the populations (F ST) ranged from 0.006 to 0.028 and the average was 0.026. The average of estimated gene flow (Nm) was high (5.27). The CG-IPA population, corresponding to the germplasm collection of IPA, showed more than 96% of genetic similarity with other populations; therefore, it is a good representative of the existent genetic diversity in the Zona da Mata region.

Seletividade de produtos fitossanitários sobre o ácaro predador Agistemus brasiliensis Matioli, Ueckermann & Oliveira (Acari: Stigmaeidae)

Os ácaros predadores das famílias Phytoseiidae e Stigmaeidae constituem-se nos principais inimigos naturais de Brevipalpus phoenicis (Geijskes) em citros. Este ácaro-praga causa sérios prejuízos na produção, devido à transmissão do vírus da leprose dos citros (CiLV). Apesar do grande volume de informações sobre a sensibilidade de ácaros Phytoseiidae a agrotóxicos, praticamente não existem informações sobre o efeito desses compostos em ácaros Stigmaeidae no Brasil. Sendo assim, o trabalho teve por objetivo avaliar o efeito dos principais agrotóxicos utilizados em citros sobre o ácaro predador Agistemus brasiliensis Matioli, Ueckermann & Oliveira (Acari: Stigmaeidae), em condições de laboratório. Arenas de folhas de citros da variedade Pera, contendo 25 fêmeas adultas de A. brasiliensis, foram pulverizadas em torre de Potter. Avaliaram-se as mortalidades dos ácaros 72 horas após a aplicação. O efeito dos produtos na reprodução do acarino e a viabilidade dos ovos também foram avaliados. Quanto à seletividade, conforme proposta da "Organização Internacional para o Controle Biológico" (IOBC), os produtos foram classificados como: classe 1 - inócuo (E<30%), acrinathrin, bifenthrin, carbosulfan, deltamethrin; 2 - levemente nocivo (30%99%), calda sulfocálcica, cyhexatin, flufenoxuron, hexythiazox, óxido de fenbutatin, propargite, pyridaben e spirodiclofen. Estudos conduzidos em condições de campo ainda são necessários para se compreender melhor o efeito desses agrotóxicos sobre o ácaro predador.