邻苯二甲酸与对羟基苯甲酸对玉米种子萌发的影响

Effects of phthalic acid and p-hydroxybenzonicacid on seed germination of maize

为明确玉米秸秆腐解的化感物质对玉米种子萌发及幼苗生长的影响,分别采用0.4、0.8、1.2、1.6和2.0mmol·L-1的邻苯二甲酸(PA)和对羟基苯甲酸(p-HBA)处理玉米品种‘庆单6号’的种子,测定根长、芽长、根系鲜重、幼芽鲜重及抗氧化系统活性,以研究PA、p-HBA对玉米种子萌发的化感机制。结果表明:化感物质PA和p-HBA对玉米萌发种子的幼芽生长的直接影响不显著,其化感效应主要来自于根系的超氧自由基(ROS)的积累。随着处理浓度的增加,根系ROS含量逐渐增加,1.6和2.0 mmol·L-1的高浓度化感物质处理显著降低根系长度和鲜重。同时,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性相应增强,协同作用清除ROS。且PA对玉米种子萌发的抑制作用大于p-HBA。加强物质分解代谢,增加物质向根系的分配,以减少根系的过氧化损伤,是玉米种子萌发过程中响应PA和p-HBA化感作用的重要机制。

The purpose of this paper is to elucidate effects of potential allelochemicals decomposed from maize stubble on seed germination of maize.Maize seeds of’Qingdan 6’were treated with 0.4,0.8,1.2,1.6 and 2.0mmol·L-1 of phthalic acid(PA)and N-phenyl-2-naphthylamine(p-HBA).The fresh weight and length,antioxidant system activity of maize root and shoot were sampled and determined in order to explore allelopathy mechanism of p-HBA and PA decomposed.The results showed that direct influence by PA and p-HBA was not significant for shoots growth during seed germination,and allelopathy was mainly caused by the accumulation of superoxide free radicals(ROS)in root system.The contents of ROS in roots gradually increased with the increase of treatment concentration,especially high concentration(1.6 and 2.0 mmol·L-1)of allelochemicals leaded length and fresh weight of roots to decrease.Accordingly,the activities of superoxide dismutase(SOD),catalase(CAT)and permoxidase(POD)of roost increased for scavenging of ROS with synergistic effect.On inhibiting effect,the function of PA was greater than p-HBA during seed germination.Important mechanisms in response to allelopathic effects of PA and p-HBA were defence against roots peroxide damage by enhance of catabolism and increase of distribution of matter to root system.