Degradating Causes Of Quality In Hops (Humulus Lupulus L.) In Hexi Region

Root exudation of hops were identified,and biological characteristics of one kind of root exudation were tested by simulated experiments;A_nd soil nutrients,soluble salinity,soil microbial were determined in field experiment,further analyzed the effects of above elements on the decline of quality in hops. The main results were:1. Root exudation of hops mainly include organic acid,phenol,hydrocarbon,mellow,ester,ketone,benzene,amine,adine,aldehyde and pyran et al. It was proved that phenol, 2,4-bis (1,1-dimethylethyl)- secreted by perennial root of hops were a kind of allelochemicals. The content of phenol, 2,4-bis(1,1-dimethylethyl)- increased with the hops growing, which was the important reason for the reduction ofα-acid content in hops.2.Pot experiment and field plot experiment were conducted,results showed that phenol, 2,4-bis(1,1-dimethylethyl)- can promote the photosynthesis of hops at the moderate dosage(7.5mmol·m^-2(A₁),15mmol·m^-2(A₂)) and has positive effect on hops growth,also can promote the biomass of hops,the higher of the dosage the stronger of the allelopathic,while it showed negative allelopathic as the dosage higher than 15mmol·m^-2 or 300×10-6mol·kg-1.soil(A₂).Compared with the control,photosynthetic rate of hops increased by 11.48%and 38.93%respectively as the treatment of phenol, 2,4-bis(1,1-dimethylethyl)- at the dosage of 7.5mmol·m^-2(A₁)and 15mmol·m^-2(A₂),and difference was significant between A₂ and control;phenol,2,4-bis(1,1-dimethylethyl)- at the dosage of 22.5mmol·m^-2(A₃)made the photosynthetic rate of hops decreased by 34.4%, the difference was significant. Phenol, 2,4-bis(1,1-dimethylethyl)- had the similar effect on transpiration rate and photosynthetic rate,while the only difference was that the index of allelopathic effect for transpiration rate was higher than that of photosynthetic rate. Compared with the control,as far as pot experiment and field plot experiment were concerned, the biomass of hops increased by 20.50% and 13.01% respectively under the treatment of phenol,2,4-bis(1,1-dimethylethyl)- at the dosage of A₁;Phenol, 2,4-bis(1,1-dimethy lethyl)- at the dosage of A₂ made the biomass of hops increased by 68.83%and 53.72% respectively,and the difference was significant. The dosage of A₃ made the biomass of hops decreased by 15.64% and 12.64% respectively.