Preliminary Study On Allelopathy Of Walnut Green Seedcase

Walnut (Juglans regia L.) is a widespread tree in walnut genus (Juglans) of walnut family (Juglamd aceas). It is planted originally for a long history in China. The output of walnut green seedcase is 350 thousands ton. For this resource was fully utilized, the economic benefit of walnut production was enhanced, this article studied the allelopathic effects of extract of walnut green seedcase with different solvents. The results indicated these:(1) Secondary material of walnut green seedcase contains bioactivity inhibiting composition. By extracting walnut green seedcase with water and organic reagents, the extracts all have certain inhibiting effect, and as concentration of extract increase, inhibiting effect strengthen..(2) Allelopathy has been influenced directly by green seedcase status and water temperature, inhibiting effect of each extract on seedling growing in order of: hot water extracting fresh sample > cool water extracting fresh sample > hot water extracting dry sample > cool water extracting dry sample; bioactivity difference of hot-water-extracting fresh sample and cool water extracting dry sample is obvious, so extracting fresh sample by hot water is suitable.(3) The compositions of cool-water-extracting fresh sample were spry to 5 kinds potted seedlings, the result shoes:â‘ The potted seedlings of wheat, tomato, rape and green been are all hurt to different extent, the inhibition ratio of fresh weight are all over 50%, the inhibition ratio is 100% for the fresh weight and height of pumpkin and green been .â‘¡The allelopathy of active compounds in walnut green seedcase is stronger to dicotyledon than to monocotyledon.(4) Ethanol extract of walnut green seedcase is extracted in turn by petroleum ether, ethyl acetate and n-butyl alcohol. It is found that active substances mainly exist in ethyl acetate phase. 2Fr2 separated by silica gel column-chromatography has high inhibiting rate over 90% on root of ryegrass and sorghum, so 2Fr2 is main active allelopathic compound for further separating and purifying.(5) The allelopathic substance of walnut green seedcase has selectivity to inhibiting young seedling, each extract has stronger inhibition on young root than on young shoot.(6) Comparing output of different methods using ethyl acetate as extracting solvent, the result shows that the output is the highest by directly taking ethyl acetate as extracting solvent. In comprehensive consideration of allelopathy, operation step and utilization ratio, extracting walnut green seedcase directly with ethyl acetate is considered as more suitable way.