Response of the Tussock Grass Stipa tenacissima to Watering in a Semi-Arid Environment

摘要: 1. Stipa tenacissima is a perennial tussock grass of arid and semi-arid zones around the Mediterranean basin that occupies extensive areas in south-eastern Spain. The environment this region extreme, with low irregular rainfall, high temperature irradiance, so S. tussocks are subjected to degree environmental stress, especially during summer months. 2. ability use pulse water applied midsummer was tested field experiment which extension growth physiological performance leaves watered unwatered plants were measured. 3. In plants, when leaf had ceased, potential, relative content, conductance net photosynthetic rate minimum fluorescence high. 4. Leaf doubled, resumed, (F 0 ) fell efficiency photosystem II v /F m rose watering. As soil dried out again, values these variables approached or equalled those plants. 5. These changes F V suggested apparatus not been damaged permanently, i.e. has reversible photoprotective mechanisms. 6. We conclude decreased results from non-damaging photoinhibition conductance. latter partly consequence folding leaves, inversely proportional content. 7. arrested development apparently due dormancy because responded opportunistically within days an water.