Physiological Responses Of Phyllostachys Edulis To The Elevated O₃and CO₂Alone And In Combination Concentration

The moso bamboo (Phyllostachys edulis) is the most important economic bamboo speciein China. The bamboo has the characteristic of widely distribution and application large areaof plantion, high value, fast growth, high output and good benefit.The bamboo plays anextremely important role in bamboo industry development and regional ecologicalenvironmental protection in China. In order to demenstrate the physiological response law ofthe moso bamboo interacting with atmospheric CO₂concentrationincreasing and provide thetheory basis for climate change under the background of bamboo forest adaptive management,the different concentration of O₃and CO₂and the compound of physiological function ofecological effects of bamboo was studied. The main research results were as follows:(1) Physiology responses of Phyllostachys edulis to elevate atmospheric ozoneconcentrationAs the ozone concentration increasing, the content of the chlorophyll, carotenoid, andSOD activity decreased; while the content of souble protein, MDA, O₂-and the activity ofPOD increased. Through treating with ozone at concentrations of100nl·L^-1and150nl·L^-1,photosynthetic pigments contents and SOD activity significantly decreased; however, solubleprotein content MDA content, O₂-content and POD activity increased, The results suggestedthat the elongated ozone exposure inhibited the growth of Ph.edulis by restricting thesynthesis or speeding the degradation of photosynthetic pigments; accelerating the aging ofleaves; intensifing the damage to membrane lipid, and destroying the structure of cellmembrane and the function of anti-oxidation system.(2) The differences of O₃stress tolerance between Phyllostachys edulis andOligostachyum lubricumUsing the principal component analysis method, the physiological indexes of the toleranceof differences O₃ability comparison of Ph. edulis and O. lubricum leaves chlorophyll andcarotenoids, MDA and soluble protein, SOD and POD activity, etc. were analysised. The results indicated that leaf Chl and MDA content was important index for the reflection of thePh. edulis and O. lubricum to the O₃stress tolerance. Although Ph. edulis and O. lubricumwere subject to the negative impact of high concentration O₃stress, the result implied that O.lubricum was much tolerant to O₃than Ph. edulis based on major factor analysis.(3) Effects of elevated CO₂on lipid peroxidation and anti-oxidation system inPhyllostachys edulisThe physiological indicators exhibited no signicicant differences between CK and500μmol·mol^-1treatment except CAT activity which decreased significantly in the initial30d.With elonged CO₂treatment, the photosynthetic pigment and membrane lipid peroxidationand anti-oxidation system in leaves of Ph. edulis were gradually impacted. After90d, thephysiological indicators increased or decreased significantly except soluble sugar. The effect of700μmol·mol^-1treatment was more significant than500μmol·mol^-1treatment on membranelipid peroxidation and anti-oxidation system in leaves of Ph. edulis. Under700μmol·mol^-1treatment, the soluble sugar concentration and anti-oxidation enzyme activity changedsignificantly in30d, and all the physiological indicators significantly changed in90d. Weconclued elevated atmospheric CO₂concentration could enhance the antioxidant capacity ofPh. edulis to a certain extent, however, the excessive accumulation of photosynthetic productscould also result in carbohydrate source-libraies imbalance and feedback inhibition of Rubiscoregeneration.(4) Effects of Elevated CO₂on the Characteristics of Leaf Nutrients in PhyllostachysedulisUnder the different concentrations of CO₂, the content of leaf C, N, P, K ranged in512.13⁵43.30,19.23²2.97,1.26⁰.96,8.40⁵.88mg/g respectively in Ph.edulis. The leafC:N,C:P,C:K,N:P,N:K,K:P in Ph.edulis ranged from26.64to23.65,406.58to565.93,60.98to92.40,15.26to23.93,2.29to3.91,7.00to6.22and27.39to32.40. Compared withthe background of environmental atmospheric, CO₂concentration increased to500μmol·mol^-1made no difference on stoichiometric characteristics of the main nutrient elements in Ph.edulis.But elevated CO₂concentration increased to700μmol·mol^-1had significant difference. Elevated CO₂concentration Ph.edulis NK restrictive effect on the growth had no obviouseffect, However, It significantly enhanced the restrictive effect of P concentration to Ph.edulisgrowth.(5) Effects of Elevated CO₂on mineral ion uptake, transportation and distribution ofPhyllostachys edulisExcept Ca²⁺concentration in the Ph.edulis organs size sorting would generate, at the CO₂concentration of700μmol mol^-1, the elevated CO₂concentration.had no significant impact tothe concentrations of Na^＋and Fe^(2+,3+)and Mg²⁺and Ca²⁺in the different Ph.edulis organs sizesorting. With the CO₂concentration increasing, the concentration of Fe^(2+,3+)in the leaf andFe^(2+,3+), Mg²⁺in the branch had no significant effect, but other mineral ion concentration inother organs had influence in some extent. The concentrations of Mg²⁺and Ca²⁺in the leaf,Na⁺and Ca²⁺in the branch, Na⁺and Ca²⁺and Mg²⁺in the stem, Na⁺and Mg²⁺in the rootincreased significantly, but Na⁺in the leaf, Fe^(2+,3+)in the stem and root, Ca²⁺in the root haddecreased significantly. The ratios of Fe^(2+,3+)/Na⁺,Mg²⁺/Na and Ca²⁺/Na⁺in the leaf,Ca²⁺/Mg²⁺in the branch, Mg²⁺/Fe^(2+,3+),Ca²⁺/Fe^(2+,3+)in all organs increased gradually,however, Fe^(2+,3+)/Na⁺, Mg²⁺/Na⁺and Ca²⁺/Na⁺in the branch and stem and root, Ca²⁺/Mg²⁺inthe leaf and stem and root decreased gradually. Except root to stem, SMg, Fefrom stem to branch,SCa,Mgfrom branch to leaf decreased significantly under the elevated CO₂concentration. otherorgan ions upward transporting ability changed or increased significantly. The study showedthat elevated CO₂enhanced more Na⁺accumulation in the root, up selective transporting abilityof Fe^(2+,3+), Ca²⁺and Mg²⁺, elevated the mineral nutrient concentrations in the leaf, andmaintained the balance of mineral elements. thereby elevated concentration of CO₂couldincrease the adaptation capacity of Ph. edulis in high CO₂concentration environment.(6) Physiology responses of Phyllostachys edulis Leaves to elevated atmospheric O₃and CO₂concentrationAfter30d of exposure, elevated O₃could stimulate the activity of anti-oxidation and thecontent of osmotic adjusting substances, which can balance reactive oxygen species production,resulting in no significantly increase in malondialdehyde content. Along with the decline of antioxidant, intense the damage to membrane lipid and destroy the structure of cell membrane.Short-term treatment of high concentration of CO₂on membrane lipid peroxidation andantioxidant system in the leaves of Ph. edulis effect was not evident, and long-term treatmentof high concentration of CO₂would increase the antioxidant ability of Ph. edulis andosmotic adjustment function in a certain extent, and thus, alleviate the oxidative stress. Incombination of elevated CO₂and O₃, the leaves of Ph. edulis could maintain high levels ofantioxidant enzymes and osmotic adjustment substances content to effectively regulate reactiveoxygen species generation and clearing balance. The results indicated that elevated CO₂couldameliorate the oxidative stress in some extent.