Transpiração e crescimento foliar de laranjeira em resposta a fração de água transpirável no solo

Abstract

Water is essential for plants and any restriction may affect the growth, development and yield of crops. The aim of this study was to determine the fraction of available soil water for transpiration (FTWS) critical leaf of seedlings of according to the coefficient of determination of linear regression .The experiment was conducted in a greenhouse at the experimental area of the Universidade Federal Pampa, Itaqui Campus - RS. The orange seedling cultivar used was 'Jaffa ' rootstock Poncirus trifoliata two years old. The available water, represented by FTSW, where transpiration was measured daily and leaf growth was measured each two days during the water deficit period of the experiment. The fit logistic regression was performed using the program R. To determine the decrease linearly, that starts to be reduced transpiration or leaf growth was used for the evaluation of the R² (Coefficient of determination of a linear regression). For the culture of the orange threshold FTSW that begins to affect transpiration, indicative of the onset of stomatal closure, was 0.9. It was observed that the transpiration of 0.9 was found to orange greater than values found for FTSW annual crops for perennial crops as well. For leaf growth was critical to FATS 0.65. It was observed that before the decreased transpiration on leaf growth relative to the FTSW, or indicates that the sweat began to be reduced to a FTSW greater than the critical leaf growth relative indicating that the plants have a mechanism orange early stomatal closure in relation to water availability in the soil. Thus, the value of FTSW to perspiration and leaf growth for culture of orange were higher than those found on field crops, indicating that the orange has good adaptation to drought stress of the soil.