Abstract: Two varieties of potato（C16：CIP397077.16 and C119：CIP398098.119）with the same growth period but different drought tolerance were selected from the resources in the International Potato Center（CIP）. Potatoes were planted in the PVC pipes where the root growth would not be restricted. The morphological characteristics,stress-resistant biochemical indicators,root tip microstructure,and ultrastructure of two potato varieties were systematically analyzed under different drought stress conditions. The results showed that drought stress led to significant increases in root length,root vigor,catalase activity,content of soluble sugar and proline,significant decreases in plant height,leaf-to-stem angle and root relative water content,and some visible changes in the core structure and the integrity of cell wall in the root tip of two varieties. These results indicated PVC-pipe-planting was ideal for studying potato root response to drought stress. Most of above indicators in C119 presented significantly better performance than C16 no matter under normal watering condition or drought stress treatment,i.e.,C119 had better adaptability to drought stress. In addition,the diameter and number of axillary xylem vessels of both varieties decreased under drought stress;moreover,the number of axillary xylem vessels of C119 with better drought resistance was significantly less than that of C16,suggesting that the potato may also resist drought stress by changing the structure of the water transport organization.

Key words: potato, drought stress, PVC-pipe-planting, physiological and biochemical indicators, microstructure