Response Of Flaveria Bidentis To Soil NaCl Stress

Flaveria bidentis(L.)Kuntze was used in the experiment. The morphological , physiological and biochemical characteristics of potted Flaveria bidentis(L.)Kuntze were studied under different NaCl stress (CK, 0.1%,0.2%,0.3%,0.4%,0.5%,0.6%). Results are as follows:1.NaCl treatment significantly inhibited the growth of Flaveria bidentis(L.)Kuntze. The height of plant and biomass increased slowly and high concentrations of NaCl treatment inhibited the growth of Flaveria bidentis(L.)Kuntze.The relative conductivity increased considerably and MDA content increased firstly and then decreased again increased over time.POD,SOD and CAT activities increased in the early days and then decreased with extended NaCl exposure. On the 6 day exposure,the activity was the highest at 0.4% NaCl. Osmoregulation substance such as free proline,soluble sugar and soluble protein had the trend that increased firstly and then decreased again increased over time.NaCl concentration will cause fatal osmotic stress when it greater than 0.4% for plants. In summary,0.4% and higher soil salinity was not suitable for the growth of Flaveria bidentis(L.)Kuntze.2.The diurnal course of net photo synthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration was significantly affected by NaCl stress,.The diurnal variation of photosynthetic parameters affected by NaCl stress: the Flaveria bidentis(L.)Kuntze net photosynthetic rate at 0.1-0.3% treatment first increased and then decreased, 0.4-0 .5% treatment slightly increased. The intercellular CO2 concentration of 0.1-0.3% NaCl treatment increased and then decreased and then increasing at last. stomatal conductance (Gs) and transpiration rate (Tr) showed a trend that first increased and then decreased.3. the Chla, Chlb and Car content of Flaveria bidentis(L.)Kuntze leaf is reduced by NaCl stress, From July 22, 2009 to August 4, 2009, the chlorophyll a, chlorophyll b, carotenoids and chlorophyll a+b of the control group and Flaveria bidentis(L.)Kuntze which treated with 0.1-0.6% NaCl decreased gradually.the chlorophyll fluorescence parameters F0 showed much higher overall,and Fm,Fv/Fm and Fv/F0 is decreased overall. and with the level and time of NaCl stress enhanced, the amplitude increase. It shows significantly different from the fluorescence parameters F0, Fm, Fv, Fv / Fm, Fv/F0 under the concentration of 0.1-0.3% and 0.4-0.6%. It indicates that bidentis was inhibited from the concentration of 0.4%. 4. the ion levels of aboveground and underground parts in plant have also changed by NaCl stress. The content of Na⁺,Ca²⁺,Mg²⁺ ion in the aboveground part is higher than the underground sections, indicating that the main organs which accumulate of Na⁺,Ca²⁺,Mg²⁺ ions is the aboveground part. The K⁺ content is in the little effect, and the absolute content of K⁺ ion in aboveground and underground parts is almost the same. the aboveground part is much bigger by the absolute terms of the Na⁺/K⁺,Na⁺/K⁺ and Na⁺/Mg⁺ and is more sensitive than the underground part under NaCl stress.