The Effect Of Different Calcium Salts On Plant Height,Photosynthesis And Permeability Of Calligonum Arborescens Under NaCl Stress

NaCl stress is one of the most important factors which can inhibit the plant’s growth. A high concentration of NaCl can even lead to plant death. Studies have shown that, calcium can alleviate NaCl stress to some extent, what’s more, the extent and mechanism of relief effect on NaCl stress can be different due to the different sorts of calcium salts and the different concentration of calcium. In this paper, we studied the alleviate effects and mechanism of different calcium to the Calligonum arborescens under NaCl stress, by measuring the height, photosynthetic and permeability of C.arborescens applied with different sorts (CaCl2 and Ca(NO3)2) and concentration of calcium under NaCl stress. The experimental design and process were as follows: 1, no any NaCl or calcium salts (CK); 2, NaCl stress treatments (4g·L-1, 8g·L-1, 12g·L-1,16g·L-1 NaCl); 3, different NaCl concentration (4g·L-1,8g·L-1,12g·L-1,16g·L-1 NaCl) applied with different CaCl2 concentration (5mM, lOmM,15mM,20mM CaCl2); 4, different NaCl concentration (8g·L-1 and 16g·L-1 NaCl) applied with different Ca(NO3)2 concentration (5mM, 10mM,15mM,20mM Ca(NO3)2). The main results are as follows:NaCl stress inhibited plant height, net photosynthetic, chlorophyll content and Fv/Fm seriously. The content of soluble sugar reduced gradually with the increase of the NaCl concentration.The proline and malondialdehyde content were rising with the increase of NaCl concentration. The changes of these metrics showed that NaCl stress had inhibited the growth of C. arborescens, and caused the osmotic stress and oxidative damage.When NaCl was 12g·L-1 or 16g·L-1, adding CaCl2 could improve the net photosynthetic and Fv/Fm, chlorophyll content, soluble sugar content, proline content, restrain the malondialdehyde content,in spite of the fact that the promoting effect of calcium chloride on plant height is not obvious, which might be due to the fact that the influence of NaCl stress on morphological index is insensitive than physiological index, namely physiological index is more susceptible to the influence of the external environment than the morphological index, all these results suggested that calcium can alleviate the inhibitory effect of NaCl stress on C. arborescens to some extent. When NaCl was 4g·L-1, the plant height, net photosynthetic and Fv/Fm, chlorophyll content, soluble sugar content of plants applied with CaCl2 didn’t be alleviated, while adding appropriate concentration of CaCl2 alleviated the Pn, Fv/Fm, chlorophyll, soluble sugar content when NaCl was 8g·L-1;the malondialdehyde content and proline content increased applying with CaCl2 when NaCl was 4g·L-1 or 8g·L-1, thus we can learn that when NaCl was 4g·L-1, the CaCl2 didn’t alleviate salt stress well, on the contrary, it aggravated the salt stress to some extent; when NaCl was 8g·L-1, adding CaCl2 can ease photosynthetic fluorescence and permeability characteristics.When NaCl was 8g·L-1, the plant height, net photosynthetic, chlorophyll content, soluble sugar content, proline content, MDA content of plants increased by Ca(NO3)2; when NaCl was 16g·L-1, the plant height wasn’t alleviated by Ca(NO3)2, however, the net photosynthetic, Fv/Fm, chlorophyll content, soluble sugar content, proline content increased then declined, MDA content declined then increased after applying with Ca(NO3)2. All these indicated that applying appropriate concentration of Ca(NO3)2 can relieve the NaCl stress to some extent, however, when the NaCl stress degree was different, the Ca(NO3)2 concentration that required was different too.The interaction of different calcium salts and NaCl had different effects on C. arborescens: when NaCl was 8g·L-1, the plant height, malondialdehyde content under Ca(NO3)2 treatments were higher than CaCl2 treatments, the net photosynthetic, Fv/Fm, chlorophyll content, soluble sugar content and proline content of plants applied with CaCl2 were higher than that of Ca (NO3) 2; when NaCl concentration was 16 g·L-1, the net photosynthetic and Fv/Fm, chlorophyll content, soluble sugar content, proline content under Ca(NO3)2 treatments were higher than those of plants under CaCl2 treatments, the plant height, malondialdehyde content of plants under CaCl2 treatments, to the contrary, were higher than those of plants under Ca(NO3)2 treatments, we suspected this result might be due to the fact that the containing Cl- concentration of 16 g·L-1 NaCl was too high, adding CaCl2 could lead to the the rther rise of Cl- at this time, causing Cl-poisoning, because Cl- and Na+ at a high concentration could inhibit NO3- and Ca2+ absorption causing ion imbalance, while Ca (NO3)2 could well make up for the shortage. From the above we can draw the conclusion:NaCl stress can restrain the growth of the C. arborescens plants, calcium salts can alleviate NaCl stress to a certain extent, and different calcium salts can alleviate NaCl stress differently, that is, when plants are under a low external (8g·L-1) NaCl concentration, the mitigation effect of CaCl2 on physiological indexes is better than that of Ca(NO3)2, with the external NaCl stress degree goes heavier (16g·L-1), the mitigation effect of Ca(NO3)2 is better.