Energy demand in soybean seeding on maize straw intercropped with forage

The sustainability of no-tillage system is fully linked to the soil use and management, in order to use technologies that promote the accumulation of dry vegetation in the soil, but it may affect the performance of agricultural machinery. Therefore, the objective of this study was to evaluate in soybean seeding the operational performance of tractor-seeder on maize straws intercropped with Urochloas in different treatments. The study was conducted in a randomized block design in factorial scheme 2 x 4 + 1, with four replications, formed by two intercropped forage species and five cropping systems. The dry maize straw, Urochloas dry mass and total straw dry mass were determined in treatments to verify the operational performance of the machines. The results showed that the amount of straw produced by maize and Urochloas interferes with the slippage of the tractor s front wheels, i.e., areas with higher amount of straw promotes lower adherence of the wheel. Energy demand was not affected by amount of straw produced by the treatments, as well as fuel consumption and operational field capacity.A sustentabilidade do sistema plantio direto está ligada ao uso e ao manejo do solo com o propósito de utilizar tecnologias que promovam o acúmulo de massa seca vegetal no solo porém podem afetar o desempenho das máquinas agrícolas. O objetivo deste trabalho foi avaliar, na semeadura da soja, o desempenho operacional do conjunto trator-semeadora sobre palhadas de milho consorciado com Urochloas em diferentes tratamentos. A pesquisa foi instalada em blocos casualizados em esquema fatorial 2 x 4 + 1, com quatro repetições, formados pelo consórcio de duas espécies forrageiras em cinco sistemas de cultivo. A massa seca de palha do milho, massa seca de Urochloas e massa seca total de palha foi determinada nos tratamentos para verificar o desempenho operacional das máquinas. Os resultados demonstraram que a quantidade de palha produzida pelo consórcio de milho com Urochloas interfere na patinagem dos rodados dianteiros do trator, ou seja, áreas com maior quantidade de palha promovem menor aderência dos rodados. A demanda energética não é afetada pela quantidade de palha produzida pelos tratamentos tal como o consumo de combustível e a capacidade de campo operacional.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Grain yield of corn at different population densities and intercropped with forages

ABSTRACT The no-tillage system optimizes agricultural areas, maintaining the supply of straw and promoting crop rotation and soil conservation. The aim of the present study was to evaluate sowing quality and grain yield of corn intercropped with three forage species of the Urochloa genus associated with two corn population densities. The experiment was conducted at the São Paulo State University (UNESP), in Jaboticabal-SP, Brazil. The experimental design was randomized blocks in a 2 x 3 factorial scheme with four replicates. The treatments consisted of two corn densities (55,000 and 75,000 plants ha-1) intercropped with three forages (Urochloa brizantha, Urochloa decumbens and Urochloa ruziziensis) sown between rows of corn in the V4 stage. The following corn variables were analysed: mean number of days for emergence, longitudinal distribution, grain yield, initial population and final population. There were differences between corn populations (p < 0.1) and the intercropping of corn with the species U. brizantha and U. ruziziensis promoted the best results, which permitted concluding that the cultivation of corn at the population density of 75,000 plants ha-1 intercropped U. brizantha and U. ruziziensis promoted better sowing quality and, consequently, higher grain yields

Isolation, Derivative Synthesis, and Structure–Activity Relationships of Antiparasitic Bromopyrrole Alkaloids from the Marine Sponge <i>Tedania brasiliensis</i>

The isolation and identification of a series of new pseudoceratidine (<b>1</b>) derivatives from the sponge <i>Tedania brasiliensis</i> enabled the evaluation of their antiparasitic activity against <i>Plasmodium falciparum</i>, <i>Leishmania (Leishmania) amazonensis</i>, <i>Leishmania</i> (<i>Leishmania</i>) <i>infantum</i>, and <i>Trypanosoma cruzi</i>, the causative agents of malaria, cutaneous leishmaniasis, visceral leishmaniasis, and Chagas disease, respectively. The new 3-debromopseudoceratidine (<b>4</b>), 20-debromopseudoceratidine (<b>5</b>), 4-bromopseudoceratidine (<b>6</b>), 19-bromopseudoceratidine (<b>7</b>), and 4,19-dibromopseudoceratidine (<b>8</b>) are reported. New tedamides A–D (<b>9</b>–<b>12</b>), with an unprecedented 4-bromo-4-methoxy-5-oxo-4,5-dihydro-1<i>H</i>-pyrrole-2-carboxamide moiety, are also described. Compounds <b>4</b> and <b>5</b>, <b>6</b> and <b>7</b>, <b>9</b> and <b>10</b>, and <b>11</b> and <b>12</b> have been isolated as pairs of inseparable structural isomers differing in their sites of bromination or oxidation. Tedamides <b>9</b>+<b>10</b> and <b>11</b>+<b>12</b> were obtained as optically active pairs, indicating an enzymatic formation rather than an artifactual origin. <i>N</i>¹²-Acetylpseudoceratidine (<b>2</b>) and <i>N</i>¹²-formylpseudoceratidine (<b>3</b>) were obtained by derivatization of pseudoceratidine (<b>1</b>). The antiparasitic activity of pseudoceratidine (<b>1</b>) led us to synthesize 23 derivatives (<b>16</b>, <b>17</b>, <b>20</b>, <b>21</b>, <b>23</b>, <b>25</b>, <b>27</b>–<b>29</b>, <b>31</b>, <b>33</b>, <b>35</b>, <b>38</b>, <b>39</b>, <b>42</b>, <b>43</b>, <b>46</b>, <b>47</b>, <b>50</b>, and <b>51</b>) with variations in the polyamine chain and aromatic moiety in sufficient amounts for biological evaluation in antiparasitic assays. The measured antimalarial activity of pseudoceratidine (<b>1</b>) and derivatives <b>4</b>, <b>5</b>, <b>16</b>, <b>23</b>, <b>25</b>, <b>31</b>, and <b>50</b> provided an initial SAR evaluation of these compounds as potential leads for antiparasitics against <i>Leishmania</i> amastigotes and against <i>P. falciparum</i>. The results obtained indicate that pseudoceratidine represents a promising scaffold for the development of new antimalarial drugs