BEHAVIOR OF SOME POTATO VARIETIES UNDER THE INFLUENCE OF THE THERMO-HYDRIC STRESS FACTORS SPECIFIC TO THE SANDY SOILS AREA

During the vegetation period, was analyzed the diurnal and seasonal variation of the physiological processes (the rate of photosynthesis and foliar transpiration) at 4 varieties and 2 lines of potato grown on sandy soils. The rate of photosynthesis showed a diurnal variation, being influenced by the active radiation in photosynthesis and air and soil humidity, as well as by the studied varieties and lines. In the tuber growth phase, the average of photosynthesis oscillated between 12,49μmol CO2/m2/s at the Castrum variety and 21,03 μmol CO2/m2/s at the L 15-1677/31. At this stage of vegetation, the L 15 line was net detached of the other varieties, having a maximum photosynthesis which has positively influenced the production of tubers, recorded at 45 days after the emergence of plants (42,4 tons/ha). The high air temperature of 37,3 °C and the relative air humidity below 30% increased the evaporation of water through foliar transpiration at all varieties and lines studied. High values at the transpiration rate were recorded at 12-15 o'clock, when the action of stress factors was maximal, at the Sarmis variety (8,35mmol H2O/m2/s), and at line L 15-1677/31 (8,74 mmol H2O/m2/s)