Responses Of Two Jerusalem Artichoke(Helianthus Tuberosus L.) Cultivars Seedling To Cadmium Stress And The Mitigation Effects Of Exogenous Of Salicylic Acid

The experiments were carried out to study the photosynthetic characteristics, difference of Cd tolerance and Cd-accumulation capacities of two Helianthus tuberosus varieties (NY5, NY2) under different Cd concentration (0,5,25,50,100, and200mg·L-1) treatments, and studied the effects of SA (0,10,100and1000μmol·L-1) on the alleviation of Cd toxicity to NY5and NY2under various Cd stresses (0,50and100μmol-L-1). The results were shown that:(1) The biomass of NY5and NY2significantly decreased under Cd stress, but the extent of reduction for NY5was less than NY2; under Cd stress the SS and Pro content increased, but SP content decreased; with the increasing of Cd concentration the activities of antioxidative enzymes increased within a certain range; the content and composition of photosynthetic pigments changed, chlorophyll content of NY5was lowest under100mg·L-1Cd stress, while the chlorophyll content of NY2was lowest under25mg·L-1Cd stress; carotenoids content of NY5under Cd stress was higher than control, while the carotenoids content decreased for NY2under Cd stress; electron transport activity of PS Ⅱ reduced; with the concentrations of Cd increasing, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) significantly decreased, while intercellular CO2concentration (Ci) was relatively stable for both NY5and NY2; water use efficiency (WUE) and stomatal limitation (Ls) of NY5had similar trends under Cd stress, and lowest at50mg·L-1Cd stress, while the changes of WUE and Ls for NY2were little; NY5and NY2had the Cd tolerance and accumulation capacity under high concentrations Cd stress, and NY5had higher capacity than NY2. The results were shown that Helianthus tuberosus may therefore be an excellent candidate for phytoremediation on Cd-contaminated environment, and NY5was better than NY2. (2) Exogenous SA alleviated the Cd harms to NY5and NY2, due to improving the growth parameters such as fresh weight and dry weight, reduced the root shoot ratio, promoted water content and nutrient elements (P, K, Mg and Ca) content, proper SA concentration can enhanced the pigments content and activities of photosynthetic parameters, alleviated stomatal limitation and reduced the Cd accumulation in two Helianthus tuberosus L. varieties seedlings, but the best suitable concentration of SA for increase of plant Cd tolerance were different either between species or among the different organs.(3) The biomass of NY5and NY2did not show significantly changes under soil Cd stress, soil Cd increased the levels of photosynthetic pigments, chlorophyll fluorescence parmeters did not change significantly, both artichokes had strong Cd-accumulate capacity, but NY5was better than NY2, leaves and stems accumulate more Cd than roots, all things considered, NY5had greater advantages for phyptoremediation planted in Cd-contaminated soils.