The Temporal Variations Of Condensed Tannin And Phenolic Acids In Needles Of Larix Gmelinii Wound Induced By Cutting Needles And Insect Feeding

Condensed tannin and phenolic acids all are important secondary plant metabolites for its resistance to insects. Larix gmelinii is main specie of forest in northeast area of China. Dendrolimus superans (Butler) boomed and serious harmful result was seen. In this research, five-year old L. gmelinii was selected as object for research. The local needles of L. gmelinii were treated with cutting needles (25% or 50% or 75% needles were cut off on four or eight or twelve branches) and larva feeding of Dendrolimus superans (25% or 50% or 75% needles were fed on four branches). Contents of condensed tannin and phenolic acids in needles on the untreated branches of L. gmelinii was detected respectively. Temporal variation of condensed tannin contents and phenolic acids contents in L. gmelinii are performed to analysis through treatment of cutting needles or insect feeding in different degree in order to study the influences of insect feeding and cutting needles to contents condensed tannin and phenolic acids in needles of L. gmelinii, and change rule of condensed tannin and phenolic acids among different time. Our research expected to offer theory support for improving the healthy level of forest and control of population density of Dendrolimus superans. After research, results were listed below:1. Temporal variation of condensed tannin contents in needles L. gmelinii are treated by cutting needles or insect feeding.(1) Both cutting needles and insect feeding could induce the increase of condensed tannin contents, compared with the control. The changes of condensed tannin contents after cutting out 75% needles on eight branches and 50 % needles on twelve branches were much higher than other cutting treatments, and the remaind time of change were also longer. Degrees of cutting needles can influence condensed tannin contents, but there were no linear relationships between them. The peak of condensed tannin contents induced by cutting needles appears earlier than that induced by insect feeding. A stress responsed is produced with the increase of condensed tannin contents in needles within certain time when L. gmelinii was induced, and then came back to the natural level gradually.2. Temporal variation of phenolic acids contents in needles L. gmelinii are treated by cutting needles or insect feeding.(1) Ten phenolic acids: benzoic acid (BEA), caffeic acid (CAA), chlorogenic acid (CHA), salicylic acid (SAA), ferulic acid (FEA), phenylacetic acid (PHA), cinnamic acid (CIA), vanillic acid (VAA), syringic acid (SYA) and gallic acid (GAA) were detected in needles of the three treatments (control, cutting needles and insect feeding).(2) Both cutting needles and insect feeding could induce the change of phenolic acids contents, compared with the control. The contents variation of phenolic acids in needles induced by cutting needles was much rapider than insects feeding, but changes trend of phenolic acids contents was similar between cutting needles and insects feeding. There were no linear relationships between degrees of cutting needles and change extent of phenolic acids contents. Compared with the other treatments of cutting needles, the changes of phenolic acids contents after cutting out 75% needles on eight branches and 50 % needles on twelve branches were much higher than other cutting treatments, and the remaind time of change were also longer.This paper made a research on temporal variation of condensed tannin contents and phenolic acids contents in L. gmelinii was induced by cutting needles or insect feeding in different degree, which indicated a stress responsed is produced with the contents changes of condensed tannin and phenolic acids in needles within certain time when L. gmelinii was induced, and then came back to the natural level gradually. Appropriate wound-treatments, which can simulate the insect's feeding, could be used to induce Larix gmelinii defense responses.