Study On Basic Biology Of Seedling Breeding And Cultivation Of Laminaria Hyperborea

Laminaria hyperborea is an economically and ecologically important kelp,it has three characteristics of"individual large,perennial and low light resistance",which can be used as an excellent algal species in the construction of marine ranching in China.In this paper,the characteristics,laws and environmental conditions of growth,development and propagation of L.hyperborea gametophytes and young seedlings are studied from the point of view of basic biology,and its purification ability to polluted water is preliminarily evaluated.?1?Study on the optimum environmental conditions for the growth of gametophyte in L.hyperborea.The conditions suitable for the culture of gametophyte were 13?,10?mol photons/?m²·s?,6 mg/L,of which the most affected was temperature,the second was nitrogen concentration,the smallest was light intensity.When cultured with different light and light intensity,Under the white light,the Fv/Fm of male gametophyte under the weak light of 0.8?mol photons/?m²·s?was significantly higher than that of 15?mol photons/?m²·s??P<0.05?.At the same light intensity,the Fv/Fm of male gametophyte under white light was significantly higher than that of red light?P<0.05?,The Fv/Fm of female gametophyte under red light was significantly higher than that of male gametophyte?P<0.05?.?2?Study on growth,physiological and biochemical characteristics of seedlings in L.hyperborea.Relative growth rate?RGR?under different environmental conditions:The RGR of light intensity 40,60 and 80?mol photons/?m²·s?group is higher;When light intensity was 20?mol photons/?m²·s?,the RGR at different temperatures was9?>13?>5?>17?>21?,When the light intensity 60?mol photons/?m²·s?,the RGR was 12?>15?>9?>18?>6?>21?,after treatment of 4d under 22?,the seedlings were seriously ill,and all the leaves were decomposed after 24? treatment of3d;The RGR of seedlings was significantly higher than that of other concentrations?P<0.05?when the nitrogen concentration was 2,4,6 and 8mg/L;The conditions suitable for the culture of seedlings were 13?,60?mol photons/?m²·s?,6 mg/L,of which the most affected was temperature,the second was light intensity,the smallest was nitrogen concentration.The RGR of the seedlings was the highest at iron ion concentration 1 mg/L,the lowest at 5 mg/L,and the high concentration of iron inhibited the growth of L.hyperborea.Photosynthetic physiological characteristics of seedlings in L.hyperborea.Both temperature and leaf length significantly affected the Fv/Fm of seedlings,Fv/Fm m was higher at 9?,12?,lower at 18?,21?,and significantly lower than other temperature groups?P<0.05?;At the same temperature,the Fv/Fm value increased gradually with the increase of seedling length,and the normal level could be restored after 21? stressed12h and restored 24h,however,the seedlings could not return to normal after processing24h.At the same time of seedling length,the light compensation point?I_c?and saturated irradiance(I_sat)of seedlings increased with the increase of temperature,but the initial slope of light response curve???decreased with the increase of temperature;At the same temperature,the I_c of 13cm seedlings was significantly lower than that of 1cm seedlings?P<0.05?,but the I_sat and?of large seedlings were significantly higher than that of small seedlings?P<0.05?.The maximal net photosynthetic rates(P_nmax)of seedlings at 9? and13? was significantly higher than that of other temperature groups?P<0.05?,and the dark respiration rate?R_d?of seedlings increased with the increase of temperature within the experimental temperature range.At the same temperature,the P_nmax and R_d of the small seedlings were significantly higher than that of the large seedlings?P<0.05?;In general,the suitable temperature range of the L.hyperborea was 9-15? and can be adapted to the weak light environment.Biochemical characteristics of seedlings in L.hyperborea:The content of soluble protein was higher in 40-80?mol photons/?m²·s?and 4-8 mg/L,which indicated that the environmental range was suitable for the growth of L.hyperborea.MDA and superoxide anion content in 20?mol photons/?m²·s?and 0-0.5 mg/L higher than the appropriate conditions,indicating that the seedlings were stressed,the accumulation of superoxide anions and severe lipid peroxidation of cell membranes lead to a decrease in RGR;The activity of antioxidant enzymes SOD,POD and CAT increased significantly under the condition of non-suitable light intensity and nitrogen concentration,which indicated that CAT,SOD and POD could work together to remove reactive oxygen species and reduce cell damage under stress environment.The content of chlorophyll?a?decreased with the increase of light intensity,so the seedlings obtained more light energy by increasing its content at low light intensity,the chloroplast was damaged by photo oxidation in high light intensity,and the content of chlorophyll?a?was decreased.When high nitrogen concentration and low nitrogen concentration stress,the content of chlorophyll?a?in seedlings was decreased,which will affect the photosynthesis of seedling.The content of carotenoids was higher at 20 and 100?mol photons/?m²·s?,indicated that it might be involved in the removal of reactive oxygen species during light intensity stress,but there was no significant increase in high nitrogen concentration and low nitrogen concentration stress.?3?Study on absorption capacity of nitrogen,phosphorus and heavy metals in L.hyperborea:The optimum temperature for nitrogen and phosphorus absorption is 9-13^oC.After 72h,the absorption rate of phosphorus,ammonia nitrogen and nitrogen nitrate was95%-98%,96%and 42%respectively,indicating that the removal rate of nitrogen nitrate,ammonia nitrogen and phosphorus by L.hyperborea are significant;The total Arsenic ions content accumulated in the L.hyperborea was 168.33 mg/kg,there is no significant difference between the surface?55%?and inner?45%?of algae,respectively;the relative growth rate was-0.92%/d when L.hyperborea were treated with arsenic ions for 6d.The total Cadmium ions content accumulated in the L.hyperborea was 15mg/kg,and the content accumulated on the surface?91%?is significantly more than inner?9%?of algae;the relative growth rate was 5.78%/d under the treatment with cadmium ions for 6d,which is lower than control condition.The total Lead ions content accumulated in the L.hyperborea was 320 mg/kg,and the content accumulated on the surface?96.5%?was significantly more than inner?3.5%?of algae;the relative growth rate is 6.73%/d under the treatment with Lead ions for 6d,which is no significant difference with control condition;The results indicated the great potential value of L.hyperborea for marine bioremediation in china.