Studies On Antifungi Effect Of The Leaves Of Myrica Rubra

This thesis primarily studied on the chemical constituents and antifungal activities of Myrica rubra leaves. The main results are as follows.1.Inhibition effects of extracts from the leaves of Myrica rubra against Botrytis cinerea, Alternaria solani, Rhizoctonia solani, Fusaium graminearum, Colletotrichum lagenarium and Setosphaeria turcica. The effects were tested by mycelium growth rate method. The results showed that the ethyl acetate phase and n-butanol phase had higher activities. The toxicity of the ethyl acetate phase and n-butanol phase to the S. turcica, B. cinerea, R. solani and F. graminearum had been tested. The ethyl acetate phase EC50 is 3.32,4.33,2.21,5.42 g·L-1,respectively, The n-butanol phase EC50 is 1.92,0.88,8.86,9.22 g·L-1, respectively.2.Ten compounds were isolated from the leaves of Myrica rubra. But R1,R2 and R3 is too few to being ideniified. The other compounds is ideniified as 2α,3β,- dihydroxyolean-12-en-28-oicacid(R4),2-dihydroxy-3-p-phnolacrylate-oleanolicacid(R5),3-O-galloyl-Dihydromyricetin(R6),quercetin-7-O-rha-mnoside(R7),myricetin-3-O-rhamnoside(R8),myricetin-3-O-rhamnoside(3-O-galloyl)(R9),yricetin-3-O-rhamnoside(2-O-galloyl)( R10). The inhibition effects of compound R6,R7,R8 and R9 had been tested by method of spore germination and the result showed that all the 4 compounds have strong inhibiting effect on the two plant pathogens.3.The main results of the development on the preparation of 30% of Extract from myrica rubra leaf emulsifiable concentrates (EC) were studied and its fungicidal activity were tested as well in this paper.The resuIts indicated that the qualities of this botanical pesticide formulation showed the better hot storage stability(30±1℃).4.The effect of 30% of Extracts from myrica rubra leaf emulsifiable concentrates (EC) on Tomato Gray Mold and Cucumber Downy Mildew was estimated in the field,The results showed the effect Was obvious that Extracts from myrica rubra leaf 0.75% EC at a 1 : 100 and 1 : 200 dilution provided 69.8% and 61.9% protection to Tomato Gray Mold,and at a 1 : 200 and 1 : 500 dilution provided 57.6% and 46.8% protection to Cucumber Downy Mildew also. Therefore, it has application value in the field efficacy trials.5.The toxicities of antiseptic which made by extracts from branches and leaves of Myrica rubra and myrecetin to non-target organisms and their safety evaluation were studied . We conclude that the toxicity of myricetin and the crude extracts from branches and leaves of Myrica rubra is generally low and it is safe for organisms in the environment。...