Adaptation Mechanism Of Casuarina Equisetifolia Provenances And Casuarina Equisetifolia Clones Under Low Phosphorus Stress

Casuarina equisetifolia is the major protection tree of our southeast coast,it has an irreplaceable effect in windbreak and sand fixation,ecological environment improvement and providing timber woods.The soil of sandyland of southeast coast is general lack of P,the lack of phophorus always becomes the important influence factor of pefect growth of Casuarina equisetifolia protection forest,and most of Casuarina equisetifolia protection forest becomed over matured,in the practise of coastal protection forest renewal,we found Casuarina equisetifolia serialize forest land has a low P content in the soil,that becomes one of the reasons of difficultise in renewal of coastal protection forest.So,developing research on physiological response and adaptation mechaanism of different varieties of Casuarina equisetifolia under low phosphorus stress,and select excellent strains of anti- low phosphorus of Casuarina equisetifolia has an important practical significance in renewal and transformation,forest soil mamagement and tainable management.This research aming at the reality problems existing in coastal protection forest management,by the purposes of selection of excellent strains of anti- low phosphorus of Casuarina equisetifolia,simulating different P nutrient environment in laboratory,choose six provenances from Australia and eight clones of Casuarina equisetifolia as test object.Developing a reasearch on adaptive mechanism of Casuarina equisetifolia seedlings under low phosphorus stress by determinationg of total water content of branchlet,C/N of branchlet,total phosphorus content of the plant, available phosphorus content in rhizosphere soil,total phosphorus content in rhizosphere soil,pH of rhizosphere soil of provenances and clones of Casuarina equisetifoliaTake donshan provenanceas as control,make different Casuarina equisetifolia provenances 18153,18154,18157,18296,18298,18312 under environment of low-phosphorus(P0)and high-phosphorus(P1).After a period of time(about 6 month),determine seed germination rate,chlorophyll content of branchlet,total water content of branchlet,C/N of branchlet,total phosphorus content of the plant,available phosphorus content in rhizosphere soil,total phosphorus content in rhizosphere soil,pH of rhizosphere soil of Casuarina equisetifolia provenances,according to the data analysis we can conclude that:provenances 18298 has the biggest thousand-seed weight and highest seed germination rate and the seed germination rate is uniform whhith field seedling emergence.Provenances dongshan has the largest height growth and ground diameter growth,but its growth is obviously different between P0 and P1 conditions;Low-phosphorus stress has no significant effect on height growth of provenances 18157,18298,18312;Dongshan provenance has a significant advantage in the biomass accumulation,but low-phosphorus stress has no significant effect on biomass accumulation of provenance 18153,18154,18157,18296,18298,18312.Under low-phosphorus stress,Dongshan provenance,provenance 18153,18154,18157,18296,18298,18312 has a significant difference in Chla & Chlb between groups.Low-phosphorus stress has an effect on total water content of Dongshan provenance and provenance 18153.Low-phosphorus stress has a direct impact on total phosphorus content in branchlet all the tested Casuarina equisetifolia provenances.Rhizosphere soil pH value is lower than those in the normal conditions;Phosphate fertilizer appliment can increase available phosphorus content in rhizosphere soil significantly,but in a short time,its has no significant impact on rhizosphere soil's total P content.Make different Casuarina equisetifolia clones:ping 2,long4,zhan1,A13,501,701,nanshan7,pu20 under controlled environment of low-phosphorus(P0)and high-phosphorus(P1).After a period of time(a year), determine indexes ofa ctivity of SOD of branchlet;Activity of CAT of branchlet;total water content of branchlet,MDAcontent of branchlet,C/N of branchlet,total phosphorus content of the plant,available phosphorus content in rhizosphere soil,total phosphorus content in rhizosphere soil,pH of rhizosphere soil of Casuarina equisetifolia clones.According to the above descriptions,we can conclude that:Low-phosphorus stress has a significant effect on the height growth of Casuarina equisetifolia clone pu20;Low-phosphorus stress has a significant effect on ground diameter growth of Casuarina equisetifolia clone 701 & nanshan 701;Under low- phosphorus stress,activity of SOD of clones ping 2,long 4,zhan 1,A13 have a dramatic decrease during the decrease of temperature,then rise again slowly;activity of SOD of clone 501 rise heavily and in November,it rise more slowly;activity of SOD of clones 701,nanshan7,pu20 exhibits a slowly rise and decrease;Under low-phosphorus stress,clones A13,nanshan7 have a larger amount of MDA content than in the normal;Rhizosphere soil pH value is lower than those in the normal conditions; Total phosphorus content of the plant of clones long 4,A13,pu20 sensitive to low-phosphorus stress Phosphate fertilizer appliment can increase available phosphorus content in rhizosphere soil significantly,but in a short time,its has no significant impact on rhizosphere soil's total P content.Through the test of the seedling stage we hold that,the different varieties of Casuarina equisetifolia can produce an irritability to low phosphorus stress,and exit as the changing in its physiological and morphological characteristics,that is adaptive mechanism.The change of provenances and clones of Casuarina equisetifolia has tight relationship whith adaptation mechanism.Under low- phosphorus stress,there has no enough available phosphorus for plant to grow,so Casuarina equisetifolia change its physiological and morphological characteristics,such as increasing in under biomass accumulation,enhancement in activity of protecetive enzyme in vivo,activating P fix in the soil by secreting more acid material,etc.to increase the absorption and utilization of P in the soil.Comprehrnsive in the index of growth,physiological and the nutrient changes of rhizosphere soils of different povenances and clones of Casuarina equisetifolia seedlings under the conditions of P0 and P1,choose provenances 18312 and clones A13,long4,zhan1,501 as the original selection of the regeneration species of shelter forest...