Diversity and aspects of the ecology of social wasps (Vespidae, Polistinae) in Central Amazonian "terra firme" forest

Diversity and aspects of the ecology of social wasps (Vespidae, Polistinae) in Central Amazonian "terra firme" forest. The knowledge of social wasp richness and biology in the Amazonian region is considered insufficient. Although the Amazonas state is the largest in the region, until now only two brief surveys were conducted there. Considering that the systematic inventory of an area is the first step towards its conservation and wise use, this study presents faunal data on social wasp diversity in a 25 km² area of "terra firme" (upland forest) at the Ducke Reserve, Manaus, Amazonas, Brazil. Wasps were collected in the understory, following a protocol of three collectors walking along 60 trails 1,000 m in extension for 16 days between August and October 2010. Methods used were active search of individuals with entomological nets and nest collecting. Fifty-eight species of social wasps, allocated in 13 genera, were recorded; 67% of the collected species belong to Polybia, Agelaia and Mischocyttarus; other genera were represented by only four species or less. The most frequent species in active searches were Agelaia fulvofasciata (DeGeer, 1773), Agelaia testacea (Fabricius, 1804) and Angiopolybia pallens (Lepeletier, 1836). Twelve species were collected in nests. Prior to this study, 65 Polistinae species were deposited at the INPA Collection. Collecting in the study grid, an area not previously sampled for wasps, resulted in an increase of 25% species, and species richness was 86. According to the results, there is evidence that the diversity of social wasps at the Ducke Reserve is even higher, making it one of the richest areas in the Brazilian Amazonia.

Hypatropis inermis (Hemiptera, Pentatomidae): first record on rice crops

This study reports for the first time the occurrence of Hypatropis inermis on upland rice crops (variety Cambará), in Novo Progresso, state of Pará, Brazil (7°07'45.71"S 55°23'21.13"W). The inventory of insect pests was conducted between November 2010 and March 2011 with entomological sweep nets and visual search on stems of rice plants. This record indicates that rice crops may represent important feeding and mating sites for this species.

Phosphorous forms in cultivated indian black earth (anthrosols) of varying texture in the brazilian Amazon

Despite the agricultural importance of Indian Black Earth (IBE) in the Amazon region, there are few studies that report on the relation between soil texture and chemical fertility of IBE. These soils of pre-Colombian origin, with high contents of P, Ca and other nutrients are found across the Amazon valley. IBE profiles were studied to evaluate the total contents of P, its primary chemical forms and the P transformation phases in areas with IBE soils of variable texture and in adjacent reference soils. The soil texture strongly influenced soil fertility, changing in terms of transformation of the primary P forms and, consequently, predominant P forms in IBE. Soils with texture varying between clay and heavy clay had higher total P contents and primary Ca-P forms. Highest P-Al and lowest total P amounts were observed at the site Rio Preto da Eva, where texture varies from sandy loam to sandy clay loam. In the IBE with clay texture the amounts of soluble P, extracted with NH4Cl were highest, although different from Mehlich 1-extractable amounts.

Characteristic of Dystrustepts in the Venezuelan Andes

The majority (60 %) of the soils in the Venezuelan Andes are Inceptisols, a large percentage of which are classified as Dystrustepts by the US Soil Taxonomy, Second Edition of 1999. Some of these soils were classified as Humitropepts (high organic - C-OC-soils) and Dystropepts by the Soil Taxonomy prior to 1999, but no equivalent large group was created for high-OC soils in the new Ustepts suborder. Dystrusepts developed on different materials, relief and vegetation. Their properties are closely related with the parent material. Soils developed on transported deposits or sediments have darker and thicker A horizons, a slightly acid reaction, greater CEC and OC contents than upland slope soils. Based on the previous classification into large groups (Humitropepts and Dystropepts) we found that: Humitropepts have a slightly less acid and higher values of CEC than Dystropepts. These properties or characteristics seem to be related to the fact that Humitropepts have a higher clay and OC content than the Dystropepts. Canonical discrimination analysis showed that the variables that discriminate the two great soil groups from each other are OC and silt. Data for Humitropepts are grouped around the OC vector (defining axis 3, principal component analysis), while Dystropepts are associated with the clay and sand vectors, with significant correlation. Given the importance of OC for soil properties, we propose the creation of a new large group named Humustepts for the order Inceptisol, suborder Ustepts.

Nitrate role in basic cation leaching under no-till

Especially under no-tillage, subsuface soil acidity has been a problem, because it depends on base leaching, which has been associated with the presence of low molecular weigth organic acids and companion anions. The objective of this study was to evaluate exchangeable base cation leaching as affected by surface liming along with annual urea side-dressing of maize and upland rice. Treatments consisted of four lime rates (0, 1500, 3000, and 6000 kg ha-1) combined with four nitrogen rates (0, 50, 100, and 150 kg ha-1) applied to maize (Zea mays) and upland rice (Oryza sativa), in two consecutive years. Maize was planted in December, three months after liming. In September of the following year, pearl millet (Pennisetum glaucum) was planted without fertilization and desiccated 86 days after plant emergence. Afterwards, upland rice was grown. Immediately after upland rice harvest, 18 months after surface liming, pH and N-NO3-, N-NH4+, K, Ca, and Mg levels were evaluated in soil samples taken from the layers 0-5, 5-10, 10-20 and 20-40 cm. Higher maize yields were obtained at higher N rates and 3000 kg ha-1 lime. Better results for upland rice and pearl millet yields were also obtained with this lime rate, irrespective of N levels. The vertical mobility of K, Ca and Mg was higher in the soil profiles with N fertilization. Surface liming increased pH in the upper soil layers causing intense nitrate production, which was leached along with the base cations.

Strategy of specification of management areas: rice grain yield as related to soil fertility

It is well-known nowadays that soil variability can influence crop yields. Therefore, to determine specific areas of soil management, we studied the Pearson and spatial correlations of rice grain yield with organic matter content and pH of an Oxisol (Typic Acrustox) under no- tillage, in the 2009/10 growing season, in Selvíria, State of Mato Grosso do Sul, in the Brazilian Cerrado (longitude 51º24' 21'' W, latitude 20º20' 56'' S). The upland rice cultivar IAC 202 was used as test plant. A geostatistical grid was installed for soil and plant data collection, with 120 sampling points in an area of 3.0 ha with a homogeneous slope of 0.055 m m-1. The properties rice grain yield and organic matter content, pH and potential acidity and aluminum content were analyzed in the 0-0.10 and 0.10-0.20 m soil layers. Spatially, two specific areas of agricultural land management were discriminated, differing in the value of organic matter and rice grain yield, respectively with fertilization at variable rates in the second zone, a substantial increase in agricultural productivity can be obtained. The organic matter content was confirmed as a good indicator of soil quality, when spatially correlated with rice grain yield.

PEDO-TRANSFER FUNCTIONS FOR ESTIMATING SOIL BULK DENSITY IN CENTRAL AMAZONIA

Under field conditions in the Amazon forest, soil bulk density is difficult to measure. Rigorous methodological criteria must be applied to obtain reliable inventories of C stocks and soil nutrients, making this process expensive and sometimes unfeasible. This study aimed to generate models to estimate soil bulk density based on parameters that can be easily and reliably measured in the field and that are available in many soil-related inventories. Stepwise regression models to predict bulk density were developed using data on soil C content, clay content and pH in water from 140 permanent plots in terra firme (upland) forests near Manaus, Amazonas State, Brazil. The model results were interpreted according to the coefficient of determination (R2) and Akaike information criterion (AIC) and were validated with a dataset consisting of 125 plots different from those used to generate the models. The model with best performance in estimating soil bulk density under the conditions of this study included clay content and pH in water as independent variables and had R2 = 0.73 and AIC = -250.29. The performance of this model for predicting soil density was compared with that of models from the literature. The results showed that the locally calibrated equation was the most accurate for estimating soil bulk density for upland forests in the Manaus region.

Effect of soil-water tension on herbaceous cotton yield

A field experiment was conducted during two years, 1990/91, in an alluvial soil, in the State of Paraíba, Brazil, to study the effect of the levels of soil-water tension, 50, 100, 200, 300, 400 and 600 kPa, at 20 cm depth, on upland cotton (Gossypium hirsutum L.r. latifolium Hutch, cv. CNPA-6H) yield. The experimental design was a complete randomized block with six treatments and four repetitions. There was an effect of the treatments on plant height, leaf area index and cotton yield, but the precocity index was not modified. Water should be applied when the soil-water tension, measured at 20 cm depth, reaches values around 200 kPa. There was a quadratic (R² = 0.893**) response of cotton yields to soil water tension, with the maximum when water was applied at 52% of soil water depletion.

Influence of micronutrients on dry matter yield and interaction with other nutrients in annual crops

The objective of this work was to determine the influence of Zn, Mn and Cu on shoot dry matter yield and uptake of macro and micronutrients in upland rice, common bean and corn. Six greenhouse experiments were conducted using a Dark Red Latosol (Typic Haplusthox). Treatments consisted of application of Zn at 0, 5, 10, 20, 40, 80 and 120 mg kg-1, of Mn at 0, 10, 20, 40, 80, 160, 320 and 640 mg kg-1 and of Cu application at 0, 2, 4, 8, 32, 64 and 96 mg kg-1. Zinc increased yield of rice, Mn increased yields of corn and bean and Cu improved yields of rice and bean. Uptake of N, Ca, and Cu in rice was decreased by zinc treatment. In common bean, uptake of N, Mg, and Cu was increased by zinc application, whereas, uptake of P was decreased. Manganese increased uptake of Mg, Zn and Fe and decreased uptake of Ca, in corn. Uptake of K, Zn and Mn was increased and uptake of P and Cu was decreased by Mn application, in bean. Copper had positive and negative interactions in the uptake of macro and micronutrients, depending on crop species and nutrients involved.

Cultivar response to fungicide application in relation to rice blast control, productivity and sustainability

Four field trials were conducted, from 1995 to 1997, with the objective of studying the response of four upland cultivars to foliar fungicide application in relation to panicle blast control, grain yield and sustainability. Differential disease control and yield response of cultivars to fungicide treatment were obtained. Losses in grain yield of cultivars IAC 202, Caiapó, Rio Paranaíba and Araguaia due to panicle blast were 44.8%, 27.4%, 24.4% and 18.2%, respectively. Two applications of tricyclazole or benomyl controlled panicle blast, as indicated by lower values of disease progress curve and relative panicle blast severity, and increased grain yield of the cultivar IAC 202. The losses in 100 panicle grain weight and grain yield were significantly reduced by 22.3% and 25.1% in IAC 202 and 23.6% and 20.5% in Caiapó, respectively, with two sprays of tricyclazole. Sustainable value index for yield was maximum with two applications of tricyclazole (0.59), followed by one application at booting (0.46) and at heading (0.40) in cultivar IAC 202. Results showed no yield response of the cultivars Rio Paranaíba and Araguaia to fungicide applications for panicle blast control.

Rhizosphere properties of rice genotypes as influenced by anoxia and availability of zinc and iron

The objective of this work was to study possible mechanisms involved in root-induced changes of rhizosphere physicochemical properties of rice genotypes, under anoxia and low supply of Zn and Fe. Two rice genotypes, including an upland and a lowland ones, were grown in hydroponic medium under adequate and low supply of Zn and Fe, with or without aeration. Anoxia increased shoot dry weight, root length and uptake of Zn and Fe in lowland Amol genotype, but reduced these parameters in upland Gasrol-Dashti genotype. The amount of oxygen released by roots was statistically higher in 'Amol'. The highest acidification potential of roots was observed in the lowland genotype under low supply of Zn, and in the upland genotype under Fe starvation. The highest oxalate (only organic acid detected) exudation from roots was observed in Zn and Fe deficient Gasrol-Dashti genotype. Zinc deficiency caused reduction of alcohol dehydrogenase and stimulation of lactate dehydrogenase activity, particularly in shoot. The ability to induce changes in the rhizosphere properties has a great contribution for the adaptation of both lowland and upland rice genotypes to specific soil conditions.

Physiological and biochemical characterization of the assai palm (Euterpe oleracea Mart.) during seed germination and seedling growth under aerobic and anaerobic conditions

Physiological and biochemical aspects of assai palm during seed germination and early seedling growth were investigated. Seeds collected from plants growing in flooded and upland forests were used to determine the influence of normoxic (aerobic) and anoxic (anaerobic) conditions in germination and the initial and average time of development in the roots and shoots. After 75 days, seedlings germinated under normoxia were transferred to trays and submitted to flooding. Seed reserves (lipids, proteins, soluble sugars and starch) were monitored for quiescent and germinated seeds maintained under normoxic and anoxic conditions, as well as after 5, 10 and 20 days of seedling growth. Alcohol dehydrogenase (ADH) activity was quantified in roots and leaves of seedlings without or with flooding (partial and total). Seeds were not able to germinate under anoxia. Different strategies of storage mobilization of lipids, proteins, soluble sugars and starch were observed in seeds of each environment. ADH activity was induced by anoxia, with the highest level observed in the leaves. This study showed that, under normoxic conditions, the best developmental performance of assai palm seeds, from flooded or upland forest areas, during germination was associated with primary metabolites mobilization and seedling flooding tolerance with increased ADH activity. We conclude that the assai palm is well adapted to the anoxic conditions provoked by flooding.

Composição florística em trechos de vegetação de caatinga e brejo de altitude na região do Vale do Pajeú, Pernambuco

(Composição florística em trechos de vegetação de caatinga e brejo de altitude na região do Vale do Pajeú, Pernambuco). Realizou-se um levantamento florístico em quatro áreas do vale do Pajeú, objetivando caracterizar a composição florística da vegetação ocorrente nas altitudes de 1100, 900, 700 e 500 m, em áreas dos municípios de Triunfo e Serra Talhada, PE. No período de setembro de 1991 a março de 1993 foram coletadas 159 espécies lenhosas. distribuídas em 45 famílias. As famílias com maior número de espécies na cota de 1100 m foram Myrtaceae (9), Flacourtiaceae e Rubiaceae (6); na cota de 900 m, foram Asteraceae, Myrtaceae e Mimosaceae (6); na de 700 m, Euphorbiaceae (6), Mimosaceae (4), Caesalpiniaceae e Anacardiaceae (3); e na de 500 m, Mimosaceae, Euphorbiaceae (7) e Caesalpiniaceae (4). Entre as quatro áreas, houve maior semelhança florística de 1100 com 900 m e de 700 com 500 m. A área de maior altitude, 1100 m, é ocupada por uma vegetação de brejo de altitude; as áreas de menores altitudes, 700 e 500 m, caracterizam-se como áreas de caatinga; enquanto a de 900 m apresenta predominantemente elementos de brejo, associados a outros de caatinga.

Physicochemical changes in cubiu fruits (Solanum sessiliflorum Dunal) at different ripening stages

Cubiu shrubs (Solanum sessiliflorum Dunal) have drawn the attention of researchers for their biological versatility (preferential heliophilous or facultative ombrophilous shrubs), their capacity to grow in upland or lowland areas, and the good technological quality of their fruits for the food industry. The aim of this study was to verify physicochemical changes in cubiu fruits during maturation. The fruits were harvested from the experimental station of olericulture of the Instituto Nacional de Pesquisas da Amazônia (INPA), Brazil. The analyses were performed in whole cubiu fruits (peel, pulp, and placenta) at four traditional ripening stages (green, turning, ripe, and fully ripe) for the determination of weight, moisture, total solids, total carotenoids, proteins, lipids, and ash. Cubiu fruits showed large weight variation, with amodal distribution. The ripe stage was critical to maintain moisture, and from that stage on, water loss became evident. The lipids increased steadily over the four ripening stages, maintaining, however, insignificant calorie content. Total carotenoids, proteins, and ash reached the maximum level at the fully ripe stage. With the exception of weight and moisture, all physicochemical changes exhibited the same general behavior, i.e. they increased as the fruits ripened at the four investigated stages.