Effects of Intercropping with Post-Grafting Generation of Galinsoga parviflora on Photosynthesis of Lettuce under Cadmium Stress

摘要

The pot experiment was conducted to study the effects of intercropping with positive and negative grafting generations of two ecotypes (farmland and mining) of cadmium (Cd) hyperaccumulator plants Galinsoga parviflora on photosynthesis of lettuce. The positive grafting: the rootstock was mining ecotype of G. parviflora (post generation was defined as mining-rootstock) and the scion was farmland ecotype of G. parviflora (post generation was defined as farmland-scion); the negative grafting: the rootstock was farmland ecotype of G. parviflora (post generation was defined as farmland-rootstock) and the scion was mining ecotype of G. parviflora (post generation was defined as mining- scion). The results show that, compared with the monoculture of lettuce, only Intercropping with mining-scion significantly increased the chlorophyll a, chlorophyll b and total chlorophyll contents of lettuce. In addition, the photosynthetic rate (Pn), stomatal conductance (Gs), CO_2 concentration of intercellular (Ci) and transpiration rate (Tr) of lettuce all significantly increased by Intercropping with mining-scion and reached maximum in all treatments. Therefore, Intercropping with mining-scion could improve the photosynthesis of lettuce under Cd stress.