平茬处理对杜仲生长及光合特性的影响

【目的】探明平茬对叶用杜仲林生长特征及光合作用的影响机制,为杜仲的定向生态培育提供参考。【方法】以3年生杜仲为研究对象,对留茬10 cm(T1)、留茬20 cm(T2)、未平茬(CK)3种处理下杜仲的生长指标、气体交换参数、叶绿素荧光参数及光合色素含量进行测定与分析,并计算主要光合生理参数,包括水分利用效率(EWU)、叶片羧化效率(EC)和气孔限制值(Ls)。【结果】平茬可使杜仲萌生枝条数、叶面积、单株叶片数、叶鲜质量、叶干质量及叶片相对含水量显著增加(P <0.05)。净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)在平茬处理下显著增加,且在T2处理组中达到最大值,与CK相比Pn、Gs和Tr分别提高31.4%、15.9%和10.1%。经平茬处理后,杜仲叶片胞间CO2浓度(Ci)显著降低,在T2处理中与CK相比下降21.7%(P <0.05)。与CK相比,T2处理中EWU和EC分别提高了10.5%和40.0%。平茬处理后,植株叶片最大光合效率(Fv/Fm)和非光化学猝灭系数(NPQ)显著增加(P <0.05)。叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量在T1处理组显著提高,与CK相比分别提高了41.3%、37.4%、40.0%和34.6%(P <0.05);叶绿素a和叶绿素b含量的比值在T2处理组显著下降(P> 0.05)。相关分析结果表明:各处理组间杜仲植株总叶片数与枝条数、Pn、Gs、Tr和Fv/Fm呈显著或极显著正相关。【结论】适度平茬有利于杜仲补偿性光合作用的产生,从而为叶用杜仲林的优产和高产提供更有利的生长条件。

Effects of stumping on growth and photosynthetic characteristics in Eucommia ulmoides

【Objective】In order to find out effect mechanism of stumping on growth characteristics and photosynthesis in leaf-used Eucommia ulmoides forest,and to provide some references for oriented ecological cultivation of E.ulmoides.【Method】Three-year-old E.ulmoides plants were used as research objects.Three treatments modes were set,which were remaining 10 cm stump(T1),remaining 20 cm stump(T2)and no stumping(CK).Growth index,gas exchange parameters,chlorophyll fluorescence parameters and photosynthetic pigments contents in E.ulmoides under each treatment were measured and analyzed.Some main photosynthetic physiological parameters were calculated,including water use efficiency(EWU),leaf carboxylation efficiency(EC)and stomatal limitation value(Ls).【Result】Through stumping,sprouting branch number,leaf area,leaf number per plant,fresh leaf mass,dry leaf mass and relative water content in E.ulmoides are significantly increased(P<0.05).Net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)are significantly increased in stumping treatments,and they reach the maximum values in T2 treatment group.Compared with CK,Pn,Gs and Tr are increased by 31.4%,15.9%and 10.1%,respectively.Intercellular CO2 concentration(Ci)in E.ulmoides leaves are decreased significantly in stumping treatments,and the index is decreased by 21.7%in T2 treatment group(P<0.05),compared with CK.Compared with CK,EWU and EC are respectively increased by 10.5%and 40.0%in T2 treatment group.The maximum photosynthetic efficiency(Fv/Fm)and non photochemical quenching coefficient(NPQ)of plant leaves are increased significantly in stumping treatments(P<0.05).In T1 treatment group,contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid are significantly increased by 41.3%,37.4%,40.0%and 34.6%(P<0.05),compared with CK.Ratio of chlorophyll a content to chlorophyll b content is decreased significantly in T2 treatment group(P>0.05).The results of correlation analysis show that total leaf number in E.ulmoides has significant or very significant positive correlation with branch number,Pn,Gs,Tr and Fv/Fm in each treatment group.【Conclusion】Moderately stumping is beneficial to compensatory photosynthesis emerging in E.ulmoides,so more favorable growth conditions are providing for E.ulmoides with high yield and high yield.