邓恩桉幼苗根系分泌有机酸对供磷浓度的响应  

Effect of Phosphorus Levels on Organic Acids in Eucalyptus dunnii Root Exudates

作　　者：牛芳华 李志辉[2] 陈少雄[3] 

机构地区：[1]河北省林业调查规划设计院,河北石家庄050000 [2]中南林业科技大学,湖南长沙410004 [3]国家林业局桉树研究开发中心,广东湛江524022

出　　处：《桉树科技》2017年第1期1-8,共8页Eucalypt Science & Technology

基　　金："948"引进国际先进林业科学技术项目(2013-4-36)

摘　　要：通过研究不同磷浓度对邓恩桉幼苗有机酸分泌的影响以探讨其对低磷的适应机理。试验采用Hoagland营养液并设置5个不同的磷浓度对邓恩桉幼苗进行培养,利用高效液相色谱(HPLC)测定根系分泌物中有机酸的种类及含量。结果表明:随邓恩桉幼苗生长,根际总体pH值呈现下降趋势,磷浓度不同下降幅度存在差异,无磷、极低磷和低磷条件下pH下降幅度最高。邓恩桉幼苗根系分泌物中所检测到的有机酸有草酸、甲酸、乙酸、苹果酸、乳酸和柠檬酸,其中草酸含量最高,磷浓度的不同对有机酸分泌的种类无影响,但6种有机酸分泌的量均在低磷水平时显著高于正常磷和高磷水平。邓恩桉幼苗根系分泌物对Al-P和Ca-P的活化能力高于对Fe-P的活化能力。根系分泌物对Fe-P的活化量不受磷浓度不同的影响,但对Al-P和Ca-P的活化能力不同,低磷环境下的根系分泌物对Al-P和Ca-P的活化量显著高于其他磷水平。邓恩桉幼苗低磷水平促进了根系6种有机酸的分泌,降低了根际周围的pH值,提高了根系分泌物对难溶磷的活化能力。The objective of this study was to examine adaption mechanisms of Eucalyptus dunnii to P deficiency by investigating the effect of P levels on organic acid in root exudates. Hoagland＇s nutrient solution was used to grow E. dunnii with 5 different levels of P nutrition. Organic acids in root exudates were analyzed by high performance liquid chromatography （HPLC） and results showed that the ph of the rhizosphere declined with sapling growth and that the range of decline was affected by the level of P nutrition. The highest rhizosphere pH＇s were observed with no added P, extremely low and low levels of P nutrition. Oxalic acid, formic acid, acetic acid, malic acid, lactic acid and citric were found in E. dunnii root exudates, with the oxalic acid being the acid present in the highest concentrations. Phosphorous levels affected the concentrations but not types of organic acids in the root exudates. The concentration of the six organic acids found in the exudates were higher under low levels than under higher levels of P nutrition. Root exudates of E. dunnii activated more P from A1-P and Ca-P than from Fe-P. The activation of Fe-P did not vary with changes in levels of P nutrition, however at low levels of P nutrition root exudates showed significantly higher activation capacity to A1-P and Ca-P than that at higher levels of P nutrition. In conclusion, under P deficiency, higher level of organic acid root exudates were induced in E. dunnii and rhizosphere pH declined. The activation capacity of root exudates to sparingly soluble P was improved at low P levels.

关 键 词：邓恩桉 有机酸 根际PH 难溶磷 根系分泌物 

分 类 号：S725.5[农业科学—林木遗传育种]