Zastosowanie termografii do badania stresu wodnego roslin i ewapotranspiracji rzeczywistej

The monograph concerns the method of radiation temperature measurements of natural meadow plants and application of these measurements for evaluation of water stress and evapotranspiration.The aim of this study was: 1. to investigate the influence of the water energy state (soil water content and soil water potential) on radiation temperature of plant cover in laboratory and lysimetric experiments 1. the comparison and verification of the models of actual and potential evapotranspiration calculation with the use of plant cover radiation temperature measurement; the realisation of this aim was performed in two stages, i.e. by evaluation and preliminary selection of the methods of évapotranspiration calculation basing on literature studies and by verification of some chosen methods in ly- simetric investigation of meadow plant cover; 2. the determination of plant water energetic status using the Crop Water Stres Index (CWSI) and its correlation with soil water potential in the soil and plants. In the monograph the role of water for plants development was described and the physical principles of mass, momentum and energy transport in the boundary layer of atmosphere were presented. The principle of infrared radiation registration with the use of thermographic systems was described as well as the factors influencing the measurement of canopy temperature. The review and analysis of the methods of actual and potential évapotranspiration evaluation were performed for selecting the method which was the subject of later verification. The investigation were performed on two maximally differentiated soils with natural meadow plant cover. The radiation temperature measurements were performed with the use of AGA 680 thermovision system (3-3,5μm) and the AGEMA 880 system (8-13μm). The radiation temperature difference between the investigated plant cover and the one in comfortable water condition is a good indicator of water stress of plants, which is determined by soil water potential, as a decisive physical factor of its accessibility for plants. The temperature difference regarding to water comfort conditions increases to 2°C when the value of soil water potential exceeds pF 3,7, which corresponds to the range of unavailable water for plants, having the maximal values of 7°C with pF 4,2, which corresponds to the plant wilting point. The actual évapotranspiration evaluation method was chosen, basing on the heat balance equation, in which radiation temperature of canopy surface is used for the determination of sensible heat flux. Two modifications of this method differing with the way of the aerodynamic resistance determination were the subject of verification. Basing on the lysimetric studies, the components of heat balance equation were analysed as well as the impact of the state of thermodynamic equilibrium in the atmosphere on the accuracy of sensible heat estimation and the utilisation of actual and potential évapotranspiration for crop water stress evaluation using of Crop Water Stress Index (CWSI).