邻苯二甲酸与对羟基苯甲酸对燕麦幼苗生长及抗氧化特性的影响

Effects of phthalic acid and p-hydroxybenzonic acid on seedling growth and antioxidant properties of oat (Avena nuda)

为明确玉米秸秆腐解的化感物质对燕麦种子萌发及幼苗生长的影响,分别采用0.2、0.4、0.6、0.8和1.0 mmol·L^(-1)的邻苯二甲酸(PA)和对羟基苯甲酸(p-HBA)胁迫处理燕麦种属裸燕麦(Avena nuda)品种‘白燕2号’的种子,测定根系鲜重、幼芽鲜重、根长、超氧阴离子自由基(ROS)含量和丙二醛(MDA)含量,以及抗氧化系统活性。结果表明:随着化感物质PA和p-HBA处理浓度的增加,燕麦根系和幼芽的ROS含量逐渐增加,诱导超氧化物歧化酶(SOD)活性逐渐增强;而过氧化氢酶(CAT)活性的变化受PA和p-HBA浓度影响较为复杂;同时,ROS积累导致了过氧化物酶(POD)活性的提高。PA和p-HBA作用导致了燕麦幼苗的膜脂过氧化,处理浓度>0.6 mmol·L^(-1)幼芽的MDA含量显著增加;根长显著降低,根冠比达到最低值。PA和p-HBA对根系的抑制程度大于幼芽,且PA的抑制作用大于p-HBA,根系损伤是两种物质对燕麦化感效应的直接体现。

The purpose of this paper is to elucidate effects of potential allelochemicals decomposed from maize stubble on germination and seedling growth of oat.Oat seeds of ‘Baiyan 2＇ were treated with 0.2,0.4,0.6,0.8 and 1.0 mmol·L（-1） of phthalic acid（PA） and p-hydroxybenzonic acid（p-HBA）.Fresh weights of root and shoot,contents of reactive oxygen species（ROS） and malonaldehyde（MDA）,antioxidant system activity of oat root and shoot were sampled and determined in order to explore allelopathy mechanism of p-HBA and PA decomposed from maize stubble.The results showed that ROS contents of root and shoot gradually increased and enhanced induced activity of superoxide dismutase（SOD） with increasing stress concentrations of PA and p-HBA,however,activity changes of CAT were much complex.Simultaneously,peroxidase（POD） activity of root were induced.Treatments of PA and p-HBA caused membrane lipid peroxidation of shoot and root in oat.Contents of MDA with treatments of over 0.6 mmol·L（-1） increased markedly,and root shoot ration tumbled to bottom with decrease of roots length.Therefore,root damage were direct reflection for allelopathic effect of PA and p-HBA,inhibition level for root was stronger than that of shoot in oat,and PA was more important than p-HBA.