遮荫对福建柏幼苗生理特性和叶绿素荧光特性的影响

Effects of shading on physiological characteristics and chlorophyll fluorescence characteristics of Fokienia hodginsii seedlings

为探讨遮荫对苗期福建柏生长的影响,本试验以1.5年生福建柏播种苗为研究对象,设置4种遮荫强度,分别为自然光(对照)、透光率50%、透光率25%、透光率12.5%,采用容器土培法研究不同遮荫强度对苗期福建柏叶绿素含量、渗透调节物质、抗氧化酶活性及叶绿素荧光特性的影响.结果表明:遮荫造成苗期福建柏叶绿素含量和主要荧光参数值增大,渗透调节物质含量和抗氧化酶活性降低.随着遮荫强度增强,叶绿素a(Chl a)、叶绿素b(Chl b)及总叶绿素(Chl a+b)含量均增加,PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在的光化学活性(Fv/Fo)、PSⅡ电子传递效率(Fm/Fo)、光适应下PSⅡ实际光量子产额(YⅡ)、光抑制时最大光合电子传递效率(ETR)、光化学猝灭系数(qP)则先升后降,过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性、可溶性蛋白、脯氨酸含量则先降后增,非光化学猝灭系数(qN)、可溶性糖含量逐渐降低.各处理间叶绿素含量存在极显著差异(P<0.01),Fv/Fm、Fv/Fo、Fm/Fo在自然光与透光率50.0%、25.0%之间,自然光YⅡ、ETR与其他3个遮荫处理间均存在显著差异(P<0.05),抗氧化酶活性、渗透调节物质含量在自然光与遮荫处理间也均存在显著差异(P<0.05);Fv/Fm、Fv/Fo、Fm/Fo、YⅡ、ETR、qP均在透光率50%处理时最高,CAT、POD、SOD活性、可溶性蛋白、Pro含量最低.研究表明,遮荫环境下,苗期福建柏光合能力、抗氧化酶活性和渗透调节物质含量发生了相应变化,其中,透光率50%遮荫最有利于福建柏苗期生长,说明适度遮荫可以改变福建柏幼苗生理特性,提高光合能力,促进生长.

To investigate the effects of shading on the growth of Fokienia hodginsii at seedling stage,1.5-year-old F.hodginsii seed-lings were subject to 4 shading intensities in pot experiment,including 50%,25%and 12.5%light transmittance and the control.Chlorophyll content,osmoregulation substance,antioxidant enzyme activity and chlorophyll fluorescence characteristics of F.hodgin-sii seedlings were monitored.The results showed that chlorophyll content and the main fluorescence parameters of F.hodginsii seed-lings overall increased under shading,and the contents of osmotic regulator and antioxidant enzyme activity decreased.With the in-crease of shading intensity,chlorophyll a,chlorophyll b and total chlorophyll contents showed uprising trends;maximal quantum yield of PSⅡ(Fv/Fm),potential activity of PSⅡ(Fv/Fo),electron transport rate of PSⅡ(Fm/Fo),actual photosynthetic effi-ciency of PSⅡ(YⅡ),maximum photosynthetic electron transport rate in photoinhibition(ETR)and coefficient of photochemical quenching(qP)all increased first and then decreased;catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)activi-ties,soluble protein and proline contents firstly declined and then increased;non-photochemical quenching coefficient(qN)and soluble sugar content gradually reduced.There were significant differences in chlorophyll content among the 4 treatments(P<0.01).Fv/Fm,Fv/Fo and Fm/Fo varied significantly between 50.0%and 25.0%light transmittance and the control.YⅡand ETR were significantly different between the control and all the treatment groups(P<0.05).Fv/Fm,Fv/Fo,Fm/Fo,YⅡ,ETR and qP were all the highest under 50%shading,while CAT,POD,SOD activities,soluble protein,proline content were the lowest.To summa-rize,under shading the photosynthetic capacity,antioxidant enzyme activity and osmoregulation substance content all changed accordingly in the leaves of F.hodginsii seedlings.Among them,moderate shading of 50%light transmittance contributes the most to the growth of F.hodginsii seedlings,resulting in improved physiological characteristics and photosynthetic capacity.