Studies On The Systemic Conductive Characteristics And Degradation Dynamics Of Phthalanilic Acid In Two Crops

As a new plant growth regulator,N-phenyl-phthalamic acid(PPA)has various functions such as promoting growth,increasing yield,improving fruit quality and increasing stress resistance to various crops such as capsicum,cowpea,soybean,corn,sunflower,etc and it shows great development potential and application prospects.However,so far,basic research on the application of this agent is relatively weak,and problems such as systemic properties and persistence in plants are not clear.In order to further establish the science and technology of this medicament and ensure its scientific and rational use,it is necessary to carry out relevant research as soon as possible.In view of this,in this study,wheat and capsicum are used as the representatives of mono-and dicotyledonous crops.The main results of the study are as follows:the way PPA enters plant tissues,the conduction law and the degradation dynamics.(1)Establishment of PPA analysis method.Using acetonitrile as the extraction solvent,combined with solid phase extraction sample purification pretreatment technology,and using HPLC as a detection method,an analytical method for PPA content in plant samples and aqueous solutions was established.In the range of 0.2 to 100.0 mg/L,the standard curve is y=36777x+3427.6(R~2=0.9999),and the limit of quantification(LOQ)in plant samples and water samples is 0.05 mg/kg and 0.03 mg/kg,respectively.The recovery rate of adding plants,seeds and water samples ranged from 81.46%to 101.45%,and the relative standard deviation was 0.9%to 8.9%.The accuracy and precision of this method are good,and it is suitable for the detection of PPA in the samples of this study.(2)PPA is easily hydrolyzed under acidic conditions(pH5).The degradation dynamics of PPA in the buffer at 25°C were detected.After 100 days,PPA was not detected in the buffer with a p H of 5,and the degradation rates in buffers with a p H of 7 and 9 were 26.1%and 5.2%;further fitting the degradation curve,the half-lives were 12.74d(pH5),223.60d(p H 7)and 1732.87d(p H 9).(3)PPA can be conducted bidirectionally in the plant.The treatment of capsicum seedlings by root immersion method showed that phenylalanine can be absorbed by the roots and conducted upwards.In high concentration treatment(200 mg/L),after 5 hours of application,the root content of capsicums rose to the highest value(33.33mg/kg).After 10hours,The content of stems and leaves reached the highest value(2.89,5.20mg/kg),then the content of each tissue part decreased and gradually stabilized;PPA can also enter the plant through the wheat roots and conduct upward,24h after application,the The content reached the highest level,and then began to decline and finally tended to balance;the ability of the roots of capsicum to absorb and accumulate benzene PPA is strong,but the ability to conduct to the top is weaker than wheat.The results of leaf application showed that PPA can be absorbed by the leaves and conducted bidirectionally.The absorption and accumulation of PPA in wheat leaves is stronger than that in capsicums,but the content of PPA in the roots of capsicums is significantly higher than that of wheat roots,indicating that PPA is transmitted to the roots in wheat The performance is weaker than capsicum plants.(4)PPA is relatively easy to degrade in crops.The application of stem and leaf spraying method and seed soaking method to wheat and capsicum was used to detect the degradation of PPA in two crop plants and seeds.The results showed that PPA was easily degraded in wheat and capsicum plants,and its digestion dynamics accorded with the first-order reaction The kinetic equations show that the degradation half-lives of wheat and capsicum plants are 3.29 d and 2.32 d,and the degradation half-lives of seeds are 1.31 d and 2.41 d,respectively.There is a slight difference in the ability to degrade phenylalanine between different plant materials.In summary,PPA is easily absorbed by roots,leaves and seeds on wheat,capsicum and other monocotyledon and dicotyledonous crops.It has good systemicity and bidirectional conductivity.It is easily degraded in crops and easily degraded in acidic water bodies.The research results provide an important theoretical basis for formulating the scientific and rational use of PPA.