稗草潜在化感物质的排查

Potential allelochemicals in barnyard grass

针对已报道属于羟基肟酸(丁布)、酚酸和酞酸酯类的稗草潜在的化感物质,本文以水稻、稗草和莴苣为试验材料,对2,4-二叔丁基酚、对羟基扁桃酸2种酚酸以及3种酞酸酯类物质的化感活性进行了研究。采用高效液相色谱法(HPLC)研究了上述5种物质以及丁布在稗草组织、根区土壤和种子萌发液的含量。结果表明:在100μg·ml-1作用浓度下,对羟基扁桃酸对莴苣、水稻以及稗草的种子萌发和幼苗生长的综合抑制活性最弱,2,4-二叔丁基酚化感抑制活性相对最强。酞酸二甲酯、酞酸二异辛酯和2,4-二叔丁基酚这3种物质对稗草的抑制活性大于水稻。通过HPLC只在稗草苗期叶、根和种子萌发液中检测出对羟基扁桃酸,其含量分别为9.72μg·g-1、7.29μg·g-1和0.24μg·ml-1,而其他生长期组织以及根区土壤中均未检出。所有样品均未检测出2,4-二叔丁基酚、丁布和3种酞酸酯类物质。对羟基扁桃酸的浓度-效应试验显示,接近实测浓度(20μg·g-1)时其对3种受试植物没有显著的化感抑制效应。本研究表明,对羟基扁桃酸不是稗草中主要的化感物质;通过HPLC-标准物质比对方法可以准确分析上述6种化合物,并证实了稗草不含有2,4-二叔丁基酚、丁布和酞酸酯类物质。

A bioassay was conducted to examine the allelopathic activities of five reported allelopathic substances in barnyard grass,i.e.,2,4-bis（1,1-dimethylethyl） phenol,p-hydroxymandelic acid,and three kinds of phthalate esters,on rice,barnyard grass,and lettuce.HPLC was used to analyze the contents of the five compounds and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one（DIMBOA） in barnyard grass tissues,root exudates,and rhizosphere soil.At concentration 100 μg·ml-1,2,4-bis（1,1-dimethylethyl） phenol had the strongest inhibitory effect on rice,lettuce and barnyard grass,while p-hydroxymandelic acid had the weakest one.Dimethyl-ester-phthalic acid,diisooctyl ester-phthalic acid,and 2,4-bis（1,1-dimethylethyl） phenol exhibited greater inhibition on barnyard grass than on rice.HPLC analysis showed that the p-hydroxymandelic acid concentration in barnyard grass shoots,roots,and root exudates at seedling stage was 9.72 μg·g-1,7.29 μg·g-1,and 0.24 μg·ml-1,respectively.No p-hydroxymandelic acid was detected at other growth stages of barnyard grass and its rhizosphere soil.2,4-bis（1,1-dimethylethyl） phenol,DIMBOA,and phthalate esters were not detected in all samples.The dose-response trial on p-hydroxymandelic acid showed no significant effect on target plants.It was concluded that p-hydroxymandelic acid was not the main allelochemicals in barnyard grass,and the reported 2,4-bis（1,1-dimethylethyl） phenol,DIMBOA,and three phthalate esters were not detected in barnyard grass.