The Photosynthetic Mechanism Of Clonal Growth Of Hippophae Rhamnoides Subsp Sinensis

Photosynthesis is the basis of plant growth and development,but it is easily affected by environmental factors.Hippophae rhamnoides subsp sinensis concentratedly distributed in the arid and semiarid areas in the north of China,drought stress is a common adversity form in these areas,it’s a direct threat to the normal photosynthetic process of H.rhamnoides subsp sinensis.So far,the researches about the photosynthetic process of H.rhamnoides subsp sinensis under drought stress,mainly included the regulation of photosynthesis and water physiology,photosynthetic physiology and plant growth,photosynthetic physiology and clone growth,etc.These researches only discussed the physiological and ecological effects of photosynthetic physiology of H.rhamnoides subsp sinensis under drought stress,lack the causality of internal mechanism and external performance.In fact,the physiological and ecological behavior of plants are changing follow the change of gene expression.Only by studying the physiological,ecological and gene regulation as a whole can we understand the mechanism of the environmental stress of H.rhamnoides subsp sinensis population declining.On the other hand,some current researches of drought stress only set up severe,moderate,mild drought these three kinds of treatment,the conditions of suitable water and too much water were ignored,that’s difficult to fully reveal the photosynthetic response laws of H.rhamnoides subsp sinensis to water condition.Because of this,this study formed through regulating irrigation intensity gradient,measure soil moisture content,tissue moisture content,gene expression quantity,photosynthetic characteristics and the change of clonal growth parameters under different irrigation intensity,according the idea of irrigation intensity--soil moisture content--tissue moisture content--photosynthetic gene expression--clone growth,talking about the photosynthetic mechanism of Hippophae rhamnoides subsp sinensis clonal growth regulation.Based on the analyses of the results,we get the following conclusions:(1)Soil moisture content is very significantly and positively correlated with irrigation intensity,rising follow the increasing of irrigation intensity.Tissue moisture content respond to irrigation intensity(soil moisture content)as a downward parabola,which increases at first and lower later.When the irrigation intensity is 5.99 times of the local average annual rainfall,tissue moisture content is the highest.(2)Clonal growth parameters(plant growth,reproductive cloning,cloning diffusion ability)respond to the irrigation intensity(soil moisture content)as a downward parabola,which increases at first and lower later;clonal growth parameters are significantly and positively correlated with tissue moisture content,which means the clonal growth parameters rised follow the increasing of tissue moisture content.(3)Photosynthetic indexes(net photosynthetic rate,chlorophyll content,etc.)respond to irrigation intensity(soil moisture content)as a downward parabola,which means these indexes increase at first and lower later;photosynthetic indexes show very significant and positive correlation with tissue moisture content,which rised follow the increasing of tissue moisture content.(4)RCA,CHLH gene expression quantity respond to irrigation intensity(soil moisture content)as a downward parabola,which increases at first and lower later;RCA,CHLH gene expression quantity shows very significant and positive correlation with tissue moisture content,which rised follow the increasing of tissue moisture content.(5)Photosynthetic characteristics and RCA,CHLH gene expression quantity are significantly related;the clonal growth parameters show very significant and positive correlation with photosynthetic characteristics.(6)With artificial contolling the irrigation intensity,we simulate the soil moisture content as the process of less--appropriate--too much,tissue moisture content of H.rhamnoides subsp sinensis increased at first and lowered later,H.rhamnoides subsp sinensis respond to tissue moisture content by regulating the quantity of RCA,CHLH gene expression,then affect the strength of the photosynthesis,which ultimately affect the ability of clonal growth and clonal growth pattern.Under less water condition,tissue moisture content is low,RCA,CHLH gene expression quantity is low,photosynthesis is weak,the ability of clonal growth is suppressed,which shows small and sparse distribution and small strains,the extension ability of clonal organs and the branching intensity is low,the clonal growth pattern tends to "guerrilla type";under suitable water condition,tissue moisture content is high,RCA,CHLH gene expression quantity is high,photosynthesis is strong,the ability of clonal growth is the strongest,which shows large-scale distribution and dense daughter plant,the extension adility of clonal organs and the branching intensity is high,the clonal growth pattern tends to "gather type";under too much water condition,the tissue moisture content is low,RCA,CHLH gene expression quantity is low,photosynthesis is weak,the ability of clonal growth is suppressed,the clonal growth pattern tends to "guerrilla type".By this token,the external moisture status of H.rhamnoides subsp sinensis affect the gene expression,gene expression affect the physiological and ecological behavior through internal regulation,external causes affect the clonal growth of H.rhamnoides subsp sinensis by internal controlling,eventually form adaptable clonal growth pattern to the external resources level.