The Photosynthetic Physiology Of The Terrestrial Bryophytes And The Application Of Their Monitoring In The Water

Currently, People pay more attention to the environmental pollution. Fontinalaceae and Amblystegiaceae have been widely applied in monitoring water environment quality. But this kind of bryophyta distributed in the Shanghai localization sparsely, the small population is difficult to monitor the water environment. Therefore, the study, which is about the survival condition of terrestrial and wet mosses in water environment , finding out terrestrial mosses that can live in the water environment, has an important application value in monitoring water environment with bryophytes. Based on Hypnum hamulosum, Brachythecium brotheri, Leucobryum glaucum and Heddigia ciliata for the determination materials to monitor photosynthetic parameters at different water immersion time, and setting different concentration and processing time about Cd²⁺ ,Cr³⁺, monitoring Hypnum hamulosum and the Brachythecium brotheri chlorophyll content MDA and POD activity, as well as concentrates ability to Cd²⁺ and Cr³⁺. The experimental results showed:(1) in natural conditions, four kinds of mosses photosynthetic active radiation - Photosynthetic response curves were: y = 8.9455ln (x) -38.973 (r2 = 0.9960, Brachythecium brotheri), Y =-18.7730+5.1738 lnX (r2 = 0.9884, Hypnum hamulosum), Y =-11.7802 +2.9732 lnX (r2 =0.9492, Leucobryum glaucum), Y = 1.3058-5.2271lnX (r2 = 0.9909, Heddigia ciliata); The light compensation point, photosynthetic saturation point, 95% of the maximum net photosynthetic rate of Brachythecium brotheri, respectively 70.9869μmol·m^-2·s^-1, 1292.35μmol·m^-2·s^-1 and 25.0973μmolCO₂g·-1·s-1; the light compensation point of Hypnum hamulosum lowest is 37.2380μmol·m^-2·s^-1, light saturation point of 1023.15μmol·m^-2·s^-1, 95% maximum net photosynthetic rate of 17.3763μmolCO₂·m^-2·s^-1; Leucobryum glaucum, the light saturation point of four kinds of mosses in the lowest of is 811.8μmol·m^-2·s^-1; Heddigia ciliata light compensation point, light saturation point, 95% of the maximum net photosynthetic rate is 46.4026μmol·m^-2·s^-1, 986.54μmol·m^-2·s^-1, 95%, and 3.7515μmolCO₂·m^-2·s^-1. They(four kinds of mosses) have higher photosynthetic compensation, compared with other terrestrial higher plants.Brachythecium brotheri, Hypnum hamulosum and Leucobryum glaucum are soaked 30d in the water,The maximum net photosynthetic rate in the natural conditions, compared to 110.78%, 80.84%, 109.63%, for the control, respectively. The three mosses can survive longer in the submerged environment. Immersed in water after 20d, Heddigia ciliata's maximum net photosynthetic rate of only 5.25% under natural conditions, indicating that this kind of bryophytes can't adapt to water environment. The analysis showed the strong relation between the photosynthetic reaction , the physical structure and habitat characteristics about these four kinds of mosses.(2) They were immersed in the water without Cd²⁺ and Cr³⁺ for14,21 and 28 days , Brachythecium brotheri chlorophyll contents were soaked in 7 days submerged in 60.77%, 58.99% and 53.36%, respectively, Hypnum hamulosum in 100.66%, 104.08% and 99.14%, respectively; the MDA content in the water of Brachythecium brotheri and Hypnum hamulosum,which were soaking under the 21d only had a small increase, while the decline about peroxidase activity were not obviously, two kinds of mosses can maintain a high photosynthetic potential(capacity) when (in the water environment)which may have relation between unobvious decrease of chlophyll content and peroxidase, the unobvious increase of MDA.(3)A single heavy metal Cd²⁺ or Cr³⁺ Stress on Brachythecium brotheri and Hypnum hamulosum of chlorophyll, MDA contents and POD activity showed that with increasing of stress concentrations and days of single Cr, Cd pollution or combined pollution. Chlorophyll content and POD activity deceased with enhancing treatment concentration and time. In low concentrations and short processing time dealing, the MDA content of Brachythecium brotheri and Hypnum hamulosum are increased. But in the high concentration and longer time, the MDA content deceased. In the Cr³⁺, Cd²⁺ pollution stress on two mosses, the MDA content of Hypnum hamulosum higher than Brachythecium brotheri, and the decline in POD activity of Hypnum hamulosum under Cd pollution higher than Brachythecium brotheri. Comparison of chlorophyll content that Hypnum hamulosum on the Cr and Cd pollution tolerance better than Brachythecium brotheri.(4)The effect of Cd and Cr combined pollution were stronger than those of single pollution. Analysis changes of two mosses of chlorophyll and MDA content ,POD activity, t Hypnum hamulosum on the Cr and Cd combined pollution tolerance better than Brachythecium brotheri. Analyze the changes in POD activity of Hypnum hamulosum at low concentrations of composite pollution tolerance better than Brachythecium brotheri.(5) Brachythecium brotheri and Hypnum hamulosum on Cd and Cr combined pollution and a single pollution. the two mosses to the Cr³⁺ and Cd²⁺ have a strong absorptive capacity. With the increasing of Cr³⁺, Cd²⁺ concentration the two mosses to absorb heavy metals in an exponential growth. The two mosses have different absorption capacity on Cd²⁺ and Cr³⁺, and Hypnum hamulosum on the absorption capacity of Cd²⁺ is greater than Brachythecium brotheri, and Brachythecium brotheri on the Cr³⁺ absorption capacity is greater than Hypnum hamulosum. After 14days of concentration(200mg.L-1) Cd pollution, the Cd content of Hypnum hamulosum.up to 3317.84mg.kg^-1, the enrichment factor up to 15.59, and the Cd content of Brachythecium brotheri also up to 1983.52mg. kg^-1. After 14days of concentration(100mg.L-1) Cr pollution, the Cr content of Hypnum hamulosum.up to 545.10mg.kg^-1, the enrichment factor up to 5.10, and the Cr content of Brachythecium brotheri also up to 818.76mg. kg^-1. Under Cd²⁺ and Cr³⁺combined pollution, Cd²⁺ and Hypnum hamulosum and Brachythecium brotheri paly mutually reinforcing roles of absorb these two elements.Based on the present research, we can found that Brachythecium brotheri, Hypnum hamulosum and Leucobryum glaucum can exist in water for 30d while maintaining a high photosynthetic capacity, This phenomena has relations with their relatively steady chlorophyll content and POD activity (no significantly decreasing) ,and their MDA activity(no significantly increasing) in water. Compared with Brachythecium brotheri, Hypnum hamulosum can be better adapted to water submerged environment and have stonger heavy metal tolerance. Brachythecium brotheri and Hypnum hamulosum have a strong absorptive capacity of Cd and Cr, which has a significant application on absorption and decontamination of Cd²⁺ and Cr³⁺ Under the two elements combined pollution. In concern of wide distribution, large biomass and easy sampling, Brachythecium brotheri and Hypnum hamulosum have potential application values in monitoring water environment, restoring water polluted by Cr³⁺ and Cd²⁺ or being a kind of aquarium plant.