Allelopathic Effects Of The Volatile From The Leaves And Breaches Of Larix Principis-rupprechtii Mayr. And Its Chemical Component

Allelopathy is an important ecochemical factor in forestry natural regeneration. Researched on allelopathic effects of Larix principis-rupprechtii Mayr., not only may further reveal some questions, such as stand productive declined and the natural regeneration ability reduced due to continuous cropping and pure forest, but also had the vital practical significance to establish high production and the highly effective cultivation technique system and promote sustainable management. This paper studied the allelopathic effects of the volatile from the leaves and breaches of L. principis-rupprechtii on its seeds germination and growth, and analyzed the chemical components of the volatile oil by GC-MS. The results showed that:(1)The volatile gas from the leaves and breaches of L. principis-rupprechtii significantly inhibited own seeds germination and growth. Compared to the control, the volatile gas test group's germination rate and the germination speed index reduced respectively 7.33%, 35.56%, the radicle length, the hypocotyl length, the radicle and the hypocotyl fresh weight reduced respectively 42.4%, 28.5%, 32.9%, 33.3% in the seeds germination stage, and reduced respectively 20.4%, 21.5%, 18.6%, 26.3% in the initial growth stage.(2)The volatile oil from the leaves and breaches of L. principis-rupprechtii also significantly inhibited own seeds germination and growth. Compared to the control, the volatile oil test group's germination rate and the germination speed index reduced respectively 12.00%, 28.06%, the radicle length, the hypocotyl length, the radicle and the hypocotyl fresh weight reduced respectively 17.5%, 22.1%, 25.0%, 21.4% in the seeds germination stage, and reduced respectively 47.7%, 13.0%, 50.5%, 5.0% in the initial growth stage.(3)Allelopathy response index(RI<0) showed that allelopathic effects manifested to inhibit. RI value of the volatile gas from the leaves and breaches of L. principis-rupprechtii test group's germination rate and the germination speed index were -0.14, -0.35, the radicle length, the hypocotyl length, the radicle and the hypocotyl fresh weight' were -0.41, -0.29, -0.329, -0.333 in the seeds germination stage, and were -0.22, -0.21, -0.505, -0.050 in the initial growth stage. RI value of the volatile oil test group's germination rate and the germination speed index were -0.18, -0.28, the radicle length, the hypocotyl length, the radicle and the hypocotyl fresh weight' were -0.17, -0.22, -0.250, -0.214 in the seeds germination stage, and were -0.48, -0.13, -0.186, -0.263 in the initial growth stage.(4)The volatile gas and oil from the leaves and breaches of L. principis -rupprechtii delayed and inhibited to its seeds germination. The effects on the length, the biomass of the radicle and the hypocotyl were different, but also had the obvious inhibition. They explained that L. principis-rupprechtii had the potentials allelochemicals and the volatile from the leaves and breaches of L. principis-rupprechtii was one of allelochemicals of release to inhibit own growth, which namely had autotoxicity.(5)The analysis results of volatile oil from the leaves and breaches of L. principis-rupprechtii showed that: The volatile oil contained 20 major components which accounted for 75.30% of the total ion peak area. The main component was Germacrene D(11.35%)1-Isopropyl-4,7-dimethyl-1,2,4a,5,8,8a-hexahydro-naphtalene (6.53%)Caryophyllene(5.84%)Patchulane(5.23%)Naphthalene,1,2,3,4,4a,5,6,8a-octahydro-7-methyl-4-methylene-1-(1-methylethyl)-(5.21%)1,6,10-Dodecatrien-3-ol,3,7,11-trimethyl-(5.17%)tau.-Muurolol(4.55%)α-Cadinol(4.31%)α-Caryophyllene(4.22%), and the others were under 4%. Terpenes and their oxidized derivatives were the major chemical constituents in the oil. There were 5 monoterpenes and 12 sesquiterpenes in the volatile oil. The inhibition effects of the volatile from the leaves and breaches of L. principis-rupprechtii on its seeds germination and growth may be related to the high content of terpenes and their oxidized derivatives.(6)The allelopathic effects of the volatile from the leaves and breaches of L .principis-rupprechtii affected own regeneration, and was a reason of artificial pure forestry degeneration. It would possibly affect distribution and the growth of nearby other species, and thus would causes its stand structure unitary, ecological amplitude reduced, the community unstable.