THE ENHANCED TOLERANCE OF INVASIVE ALTERNANTHERA PHILOXEROIDES OVER NATIVE SPECIES UNDER SALT-STRESS IN CHINA

Effects of environmental stress (e.g. salt stress) on the plant invasions are still relatively unknown. Therefore, we analyzed the physiological characteristics of Alternanthera philoxeroides (Mart.) Griseb. as an invasive plant and Alternanthera sessilis (L.) R.Br. ex DC. as a native plant under single and mixed planting, in green house, Jiangsu University, China Plants were subjected to four different levels of salt stress treatments "i.e.", control, low (0.8%), medium (1.6%) and high (2.4%) that were made with equal proportion of NaCl and CaCl2 followed by rewatering. The results showed, that different levels of salt stress affect the plant growth of both species differently. The net photosynthetic rate (Pn) for A. philoxeroides was higher from low to high stress of both single and mixed planting that of A. sessilis. Afterwards, during rewatering, the increments in Pn from low to high salt stress were also found higher in A. philoxeroides. In addition, the reduction in photosynthetic activity in A. sessilis under mixed planting during salt stress markedly affected the plant growth. After rewatering the comparative increments in plant growth parameter were also noted higher in A. philoxeroides than A. sessilis. Our results thus suggest that A. philoxeroides may possess a better adaptability to salt stress, which results in a successful competitive dominance.