Taking the ursolic acid as the reference,5% vanillin-acetic acid and perchloric acid as color system,the content of total triterpenoidic in the leaves and stems of Polyalthia rumphii was determined by ultraviolet spectrophotometric method at 546 nm.The calibration curve was linear(R2=0.999 4)in the range of 0.2～1.6 μg/mL,and the curve was A=0.160 3 C+0.031 2,the content of total triterpenoidic in the leaves and stems of P.rumphii was 0.956% and 0.446% respectively.The result was stable and repeatable.This method was operated conveniently and spread easily.

The prevention and control effects of pesticide and fertilizer such as Xijunteke bactericide,Nutrient enhancing balancer(NEB),Nashi 778 growth regulator and Zhengda nutrition treasure against soft rot in konjac Amorphophallus konjac was researched.The results showed that the best effect of single pesticide and fertilizer in soft rot disease was Nashi 778 growth regulator,followed by NEB,and then Zhengda nutrition treasure and Xijunteke bactericide.The best effect of composite formulations was Nashi 778 + NEB + Zhengda nutrition treasure,secondly Nashi 778 + Xijunteke bactericide + Zhengda nutrition treasure.

现在魔芋种植业面临的最大问题和威胁就是软腐病,该病害发生时产量损失一般在30%~50%,严重时达80%以上甚至绝收,农民是"谈芋色变"[1].针对这种情况,抗病育种显的尤为突出,但至今未发现具抗病性的类型,目前还是以药剂防治为主[2].

Based on the 3414 fertilizer effect experiment in Lichuan city,the effects of N,P and K fertilizer on Amorphophallus konjac were studied;different fertilizer models(three-factor model and one-factor model) were built.The results showed that balanced fertilization effectively increase the yield of konjac,excessive fertilization especially P lead to low yield.According to experimental soil properties,the balance fertilizer rate was as follows:N fertilizer 354 kg/hm2,P2O5 fertilizer 34.5 kg/hm2,and K2O fertilizer 51 kg/hm2,the optimum yield is 11 446.5 kg/hm2.

According to the analysis of ITS sequence and biological characteristics, the pathogen was identified as Sclerotium rolfsii Sacc., Agonomycetales, Hyphomycetes and Deuteromycotina. The results showed that the lethal condition of mycelium was at 50℃ for 15 min, the optimum pH value of medium was 4～5, and its optimum carbon and nitrogen source were soluble starch and ammonium nitrate respectively.

以西盟魔芋芽鞘为外植体,研究了不同浓度激素配比对愈伤组织诱导、芽分化及植株再生的影响.结果表明: 愈伤组织诱导适宜培养基为:MS+6-BA 1.5 mg/L+NAA 0.2 mg/L,芽分化和增殖培养基为MS+6-BA 1.2 mg/L+NAA 0.2 mg/L,壮苗及生根培养基为1/2MS+NAA 0.1 mg/L.

A molecular marker SRAP(sequence-related amplified polymorphism) was used to detect DNA polymorphism among the 36 sweet potato(Ipomoea batatas)accessions from different regions.Six pairs of primers with polymorphism among 36 accessions were used to amplify the genomic DNA.A total of 112 polymorphic bands were generated,110 of them were polymorphic bands,with an average of 18 maker bands per pair of primers.The dendrogram generated by UPMGA showed the genetic relationship among 36 accessions.The genetic similarity among 36 accessions varied from 0.62 to 0.92.In the dendrogram,there was no obvious genetic diversity between Asian accessions and American accessions,indicating that there was not geographic differentiation in sweet potato.Wild relative I.trifida(6×) clustered together with other sweet potato cultivars without distinct genetic differentiation,which suggested there was high genetic coefficient between them.And there was high genetic similarity among Chinese cultivars because they clustered together.