Photoacoustics As A Tool For The Diagnosis Of Radicular Stress: Measurements In Eucalyptus Seedlings

The application of the open photoacoustic cell (OPC) to investigate the behavior of eucalyptus leaves by the availability of soil and nutrients for the seedlings was discussed. Fluorescence and photosynthetic rate were evaluated in vivo and in situ, the latter one using the open photoacoustic technique. It was shown that the photosynthetic behavior of seedings are affected by radicular stress, with the soil volume of the pot becoming insufficient for the roots, causing a nutritional deficiency in plants.741 II709711Fork, D.C., Herbert, S.K., (1993) Photochem. Photobiol., 57, p. 207Malkin, S., Canaani, O., (1994) Annu. Rev. Plant Physiol. Plant Mol. Biol., 45, p. 493Malkin, S., Puchenkov, O., (1997) Progress in Photothermal and Photoacoustic Science, Life and Earth Sciences, 3, pp. 17-56. , edited by A. Mandelis and P. Hess (SPIE, Bellingham, WA)Herbert, S.K., Han, T., Vogelmann, T.C., (2000) Photosynth. Res., 66, p. 13Malkin, S., (1987) Planta, 171, p. 65Perondi, L.F., Miranda, L.C.M., (1987) J. Appl. Phys., 62, p. 2955Marquezini, M.V., Cella, N., Mansanares, A.M., Vargas, H., Miranda, L.C.M., (1991) Meas. Sci. Technol., 2, p. 396Pereira, A.C., Neto, G.D.O., Vargas, H., Cella, N., Miranda, L.C.M., (1994) Rev. Sci. Instrum., 65, p. 1512Silva, W.J., Prioli, L.M., Miranda, L.C.M., Cella, N., Vargas, H., Mansanares, A.M., (1995) Plant Sci., 104, p. 177Barja, P.R., Mansanares, A.M., (1998) Instrum. Sci. Technol., 26, p. 209Blake, S.T., (1977) Austrobaileya, 1, p. 7Pryor, L.D., Williams, E.R., Gunn, B.V., (1995) Aust. Syst. Bot., 8, p. 7Inoue, M.T., Oda, S., (1998) Proceedings of the International Symposium on Forest Tree Physiology, p. 69. , NancyBarja, P.R., Mansanares, A.M., Da Silva, E.C., (2001) Acoust. Phys., 47, p. 1

Períodos de dessecação de urochloa ruziziensis e seu reflexo na produtividade da soja RR

Two field trials were carried out to evaluate the effects of burn-down timing of Urochloa ruziziensis on transgenic soybean establishment and yield under the no-tillage system. One experiment was conducted in Colina, SP - Brazil, in 2007/2008 season, and the other in Jaboticabal, SP - Brazil, 2009/2010 season. In 2007/2008, the experiment was carried out in a 7-year-old grass pasture of U. ruziziensis, with four burn-down timings of vegetation cover being tested 30, 20, 10, and 0 days in advance to soybean sowing. In 2009/2010, the experiment was conducted in an old grass pasture of U. ruziziensis cropped with maize the summer before. After maize harvesting, a natural re-infestation of U. ruziziensis occurred, corresponding to more than 80% of the vegetation cover. In this experiment, treatments corresponded to six burn-down timings of vegetation cover 25, 20, 16, 7, and 0 days in advance to soybean sowing. In all experiments, 1.44 kg a.e. ha-1 of herbicide glyphosate was applied, and the soybean cultivar M-SOY 7908 RR was used. The experiments were arranged in a randomized block design, with four replicates. The evaluations were carried out by measuring crop stand 20 days after sowing and pre-harvest, plant height, first pod insertion height, number of pods per plant, grain yield, and estimated yield. Data were submitted to ANOVA and the Tukey test at 5% of probability. Burn-down of U. ruziziensis performed at the same day of crop sowing reduced plant height, number of pods per plant, and crop grain yield. Burn-down timing of U. ruziziensis using glyphosate was recommended to be between 10 and 20 days in advance to crop sowing. In conclusion, soybean yield was affected by burn-down timing of U. ruziziensis