外源酚酸对降香黄檀幼苗生理的化感效应

为了研究巨尾桉根系分泌物中酚酸对降香黄檀生长的影响,以2年生降香黄檀幼苗为试验材料,参照二代巨尾桉-降香黄檀人工林土壤中6种酚酸含量(X),设置3个酚酸浓度(0.5X、1.0X和2.0X,以蒸馏水作为对照)处理,分析其对降香黄檀幼苗叶片叶绿素荧光特性、光合色素含量、抗氧化酶活性以及细胞膜透性等指标的影响。结果表明:不同质量浓度酚酸处理对降香黄檀幼苗叶片叶绿素荧光和光合色素含量的抑制作用较为明显。在2.0X浓度处理下,降香黄檀幼苗叶片最大荧光产量(Fm)、PSⅡ最大光化学效率(Fv/Fm)、类胡萝卜素含量、叶绿素a和总叶绿素含量的化感效应指数均小于0;在0.5X和1.0X浓度处理下,过氧化物酶(POD)活性受到抑制,提高了过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性,而在2.0X浓度处理时,3种酶的化感效应指数均小于0;随着酚酸浓度的增加,丙二醛(MDA)含量逐渐增加。通过综合敏感指数可知,6种酚酸对降香黄檀幼苗产生一定的抑制效应,但不同酚酸的作用方式及强度存在差异,苯甲酸的化感影响最大。

Allelopathic effects of exogenous phenolic acids on the physiological characteristics of Dalbergia odorifera seedlings

To study the allelopathic effects of phenolic acids in root exudates of Eucalyptus urophylla on the growth of Dalbergia odorifera,two-year-old D.odorifera seedlings were used as experimental materials.Based on the actual content of phenolic acid in the soil of a second-generation E.urophylla-D.odorifera forest(X),three concentrations of phenolic acids were set(0.5 X,1.0 X,and 2.0 X,with distilled water as the control)to evaluate the effects on chlorophyll fluorescence,photosynthetic pigment content,antioxidant enzyme activities,and cell membrane permeability of D.odorifera seedlings.The results showed that phenolic acids at different concentrations inhibited chlorophyll fluorescence and photosynthetic pigment content in D.odorifera seedlings.The allelopathic effect index of the maximal fluorescence(F m),maximal photochemical efficiency(F v/F m)and chlorophyll a,chlorophyll a+b,and carotenoid content in the leaves of D.odorifera seedlings under 2.0 X treatment was less than 0.Under 0.5 X and 1.0 X treatments,the activity of peroxidase was inhibited and that of catalase and superoxide dismutase was increased,whereas under 2.0 X treatment,allelopathic effects on the three enzymes were observed,and the index was less than 0.With the increase in phenolic acid concentration,the content of malondialdehyde in the leaves increased gradually.According to the comprehensive sensitivity index,six phenolic acids had certain inhibitory effects on D.odorifera seedlings,but the action mode and phenolic acid concentrations were different.Benzoic acid had the highest allelopathic effect.