The healthy development of potato tubers requires, among other agricultural practices, proper fertilization. Potato crops require large amounts of nutrients, and therefore consume a large amount of fertilizer. In Brazilian soils, phosphorus is the nutrient that produces the highest response in tuber yields. The objective of this work was to study the effect of different levels of phosphorus fertilizer on the potato cultivar Ágata, by evaluating foliar levels of phosphorus and tuber yield under field conditions. The experiment was conducted at the Experimental Station of the Agriculture Cooperative Alto Paranaíba (COOPADAP) in Rio Paranaiba, Minas Gerais, during the 2008/2009 growing season. Treatments consisted of five doses of phosphorus (P 2 O 5 ) (0, 200, 400, 600, and 800 kg ha -1 ), with superphosphate as the source. The phosphorus content in the leaves of potato plants decreased with increasing doses of phosphorus in the soil. The crop showed an increase in tuber productivity with increasing doses of phosphorus, reaching a maximum estimated productivity of 49.11 t ha -1 with the application of approximately 700 kg ha -1 P 2 O 5 .

Productivity of sweet corn and green corn genotypes according to harvest intervalsSweet corn is a vegetable crop with high added value basically intended for human consumption due to the flavor of the grains. Brazil has the potential to expand its production, but more studies are needed to support and tune high yields and product quality. The productivity and grain yield of hybrid sweet corn and green corn were evaluated according to harvest intervals. The experiment was carried out at the Experimental Research Station of Syngenta Seeds Ltda., in the city of Uberlândia, Minas Gerais state, Brazil. The experimental design was a randomized block in factorial 8x4, corresponding to six hybrids of sweet corn (SWC03, SWC04, SWC05, SWC06, SWC07 and SWC08), and two hybrids of green corn (SWC01 and SWC02) and four harvest intervals [26, 28, 30 and 32 days after flowering (DAF)], with three replications. Sweet and green corn could be harvested when the grains contain from 72 to 78% humidity (milky stage), which occurs between 20 to 28 DAF. The hybrids SWC04 and SWC08 presented the highest productivity of ears with straw, productivity of grains and yield when harvested at 30 DAF (24.38 and 22.18 t ha -1 ; 11.70 and 10.95 t ha -1 and 47.96 and 49.30%, respectively).

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-Yellow passion fruit has conquered a significant position in the agribusiness of tropical fruits; therefore, farmers have been interested in expanding their groves, and technical information that guarantees the high yield of the farmings is needed. Aiming to observe factors related to the propagative material targeted at quality and maximization of the genetic potential, the objective of the study consisted in assessing germination and emergence of passion fruit seeds collected in three positions in the fruits and submitted to different methods of mucilage removal (aryl). The passion fruits were split in three parts: distal, medial and proximal and the contents of each part was divided in two. The content of each part of the fruit was submitted to mechanical and by fermentation methods for removal of aryl. It is concluded that the seed position in the fruit does not interferes with the germination. The aryl removal method by mechanical extraction affects the germination and seedling emergence.Index terms: Passiflora edulis, mechanical extraction, fermentation, propagation, mucilage. Métodos de remoção do arilo e posições das sementes no fruto de maracujá:Germinação e emergência RESUMO -O maracujá-amarelo conquistou significativa posição no agronegócio de frutas tropicais, com isso, produtores despertaram interesse para expandir seus pomares, sendo necessárias informações técnicas que garantam a alta produtividade das lavouras. No intuito de observar fatores relacionados ao material propagativo visando a qualidade e a maximização do potencial genético objetivou-se avaliar a germinação e a emergência de sementes de maracujá coletadas em três posições nos frutos e submetidas a métodos de retirada da mucilagem (arilo). Os frutos de maracujá foram seccionados em três partes: distal, mediana e proximal. Cada um destes conteúdos foi submetido aos métodos mecânico e de fermentação para remoção do arilo. Podendo concluir que a posição da semente no fruto do maracujazeiro não interfere na germinação e o método de remoção do arilo por extração mecânica prejudica a germinação e a emergência de plântulas.Termos para indexação: Passiflora edulis, extração mecânica, fermentação, propagação, mucilagem.

In this work, a chemical model for the camphene ozonolysis, leading to carbonyl final products, is proposed and discussed on the basis of the thermochemical properties and kinetic data obtained at density functional theory levels of calculation. The mechanism is initiated by the electrophilic attack of ozone to the double bond in camphene leading to a 1,2,3-trioxolane intermediate, which decomposes to peroxy radicals and carbonyl compounds in a total of 10 elementary reactions. The thermodynamic properties (enthalpy and entropies differences) are calculated at 298 K. For the thermochemical evaluation, theoretical calculations are performed with the B3LYP, MPW1PW91, and mPW1K density functionals and the basis sets 6-31G(d), 6-31G(2d,2p), 6-31+G(d,p), and 6-31+G(2d,2p). Eventually, single point calculations adopting the 6-311++G(2d,2p) basis set are performed in order to improve the electronic energies. The enthalpy profiles suggest highly exothermic reactions for the individual steps, with a global enthalpy difference of -179.18 kcal mol(-1), determined at the B3LYP∕6-31+G(2d,2p) level. The Gibbs free energy differences for each step, at 298 K, calculated at the B3LYP∕6-311++G(2d,2p)∕∕B3LYP∕6-31+G(2d,2p) level, are used to estimate the composition of a final product mixture under equilibrium conditions as 58% of camphenilone and 42% of 6,6-dimethyl-ɛ-caprolactone-2,5-methylene. For the reaction kinetics, the bimolecular O(3) + camphene step is assumed to be rate determining in the global mechanism. A saddle point for the ozone addition to the double bond is located and rate constants are determined on the basis of the transition state theory. This saddle point is well represented by a loosely bound structure and corrections for the basis set superposition error (BSSE) are calculated, either by considering the effect over the geometry optimization procedure (here referred as CP1 procedure), or the effect of the BSSE over the electronic energy of a previously optimized geometry, included a posteriori (here referred as CP2). The rate constants, calculated at 298 K from the data obtained at the mPW1K∕6-31+G(d,p), CP1∕B3LYP∕∕6-31+G(2d,2p), and CP2∕B3LYP∕∕6-31+G(2d,2p) levels (3.62 × 10(-18), 1.12 × 10(-18), and 1.39 × 10(-18) cm(3) molecule(-1) s(-1)), are found in good agreement with the available experimental data at the same temperature, 0.9 × 10(-18) cm(3) molecule(-1) s(-1) [R. Atkinson, S. M. Aschmann, and J. Arey, Atmos. Environ. 24, 2647 (1990)]. The importance of the BSSE corrections for the final rate constants must be pointed out. Furthermore, this work will contribute to a better understanding of the chemistry of monoterpenes in the atmosphere, as well as the implications for the phenomena of pollution.

Here, a new implementation for calculating canonical variational rate constants is introduced and tested against methanol dissociation rate constants and the (high pressure) radical recombination reaction, CH 3 þ OH ! CH 3 OH. Reaction paths are described at the CASSCF level, with energy corrections at MRMP2. Molecular properties for both stationary and non-stationary points along the reaction path are used for the calculation of rate constants. Different models for the low vibrational frequencies are discussed: harmonic oscillator and free rotor models. The CH 3 þ OH ! CH 3 OH recombination rate constants are determined from dissociation rate constants and equilibrium constants. Our calculated rate constants agree with previously reported data for these reactions, suggesting the good performance of our implemented code in calculating canonical variational rate constants. The rate expressions are suggested: as: k dis (T) ¼ 8.42 Â 10 þ16 Â e À96.18/RT and k rec (T) ¼ 2.05 Â 10 À10 Â (T/298) À0.24 Â e À0.30/RT , in units s À1 and cm 3 molecule À1 s À1 , respectively, and over the temperature range 300-2000 K, with activation energies in kcal/mol.

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Purpose Due to the pressures of conforming to environmental quality standards and the increased costs of mineral fertilizer importation, there is growing interest in the use of organic residues as fertilizers. To test the hypothesis that indicates the quantity of animal manure (AM) depends on the phosphorus (P) needs of the crops, an experiment was run using three organic animal manures (chicken-CM, turkey-TM, and cow manure-CoM), enriched with limestone, gypsum, and phosphorus. Methods A greenhouse experiment was run using AM incorporated in a clayey soil, at a rate that equates to the P needs of Brachiaria sp. Contents of phosphorus, potassium (K + ), calcium (Ca +2 ), magnesium (Mg +2 ), sodium (Na + ), organic matter (OM), and values of pH and cation exchange capacity (CEC) were monitored during 120 days. Plants were collected to determine the dry matter.