Morfogênese de braquiárias sob estresse hídrico / Morphogenesis of Brachiarias species under water stress

Objetivou-se avaliar Urochloa spp. submetida a duas situações de estresse hídrico: déficit e alagamento. As forrageiras estudadas foram: U. humidicola cv. Tully, U. humidicola cv. Llanero, U. brizantha cv. BRS Piatã, U. brizantha cv. Xaraés, U. decumbens cv. Basilisk e U. ruziziensis cv. Kenedy, e os parâmetros avaliados foram relacionados às características estruturais e morfogênicas. O trabalho foi desenvolvido em casa de vegetação pertencente à Unidade Universitária de Aquidauana. Os tratamentos consistiram em diferentes condições de umidade do solo: 50 e 80% da capacidade de retenção de umidade do solo, e lâminas de 0cm, 1cm e 5cm de água acima do solo, com quatro repetições, em delineamento inteiramente ao acaso. O modelo considerou o efeito de umidade do solo para cada espécie forrageira a 5% de significância. As características estruturais e morfogênicas do capim-tully não foram afetadas pelas diferentes condições hídricas aqui avaliadas. O capim-llanero não reagiu ao alagamento. O capim-piatã foi tolerante às condições de déficit hídrico e apresentou mecanismos de adaptação ao alagamento. A U. decumbens cv. Basilisk apresentou respostas adaptativas que melhoram sua tolerância ao alagamento. A U. ruziziensis cv. Kenedy apresentou-se inapta às condições de alagamento e de déficit hídrico.(AU)

The aim of this study was to evaluate braquiarias submitted to two situations of water stress: deficit and flood. The studied forages were: U. humidicola cv. Tully, U. humidicola cv. Llanero, U. brizantha cv. BRS Piatã, U. brizantha cv. Xaraés, U. decumbens cv. Basilisk and U. ruziziensis cv. Kenedy, and the parameters evaluated were related to the structural and morphogenic characteristics. The work was carried out in a greenhouse at the University Unit of Aquidauana. The treatments consisted of different soil moisture conditions: 50 and 80% of the moisture retention capacity of the soil, and slides of 0cm, 1cm and 5cm of water above the soil, with four replications, in a completely randomized design. The model considered the effect of soil moisture for each forage species at 5% of significance. The structural and morphogenic characteristics of grass-tully were not affected by the different water conditions evaluated here. The grass-llanero did not react to flooding. The grass-piatã was tolerant to water deficit conditions and presented adaptation to flooding. The U. decumbens cv. Basilisk presented adaptive responses that improved its tolerance to flooding. The U. ruziziensis cv. Kenedy was unfit for flood and water deficit conditions.(AU)

Capim-piatã adubado com fontes de fósforo de diferente solubilidade em água / Piata palisadegrass fertilized with different sources of phosphorus for solubility in water

The development of piatã grass fertilized with phosphorus sources with different solubilities in water was evaluated. The experiment was developed in the unit of Aquidauana of UEMS, MS, from February to August, 2012. Four treatments were evaluated: control (without phosphorus fertilization), slow solubility, fast solubility (readily available), and mixed solubility sources of phosphorus (FH Pasture(r)). It was adopted a randomized blocks design with four blocks and four replicates in a total of 16 pastures (0.5 ha each one). Measurements were performed weekly to evaluate structural characteristics and morphogenic variables of the plants. Data were submitted to a variance analysis according to the model. When necessary, the means of treatments with different phosphorus fertilizer sources were compared with the control using the Dunnett test and with other treatments by using student's t test. The significance level of 5% was adopted in all analysis. No significant effect was observed (P 0.05) in the evaluated traits in the first year of the experiment.