| Planting Chinese herbal medicine under forest is one of the main models of developing forest economy.Polygonatum cyrtonema is known as the traditional Chinese medicine,medicine and food homology,which has the effect of reducing blood fat and sugar,and has high medicinal value.We took the Polygonatum cyrtonema which was planted under Phyllostachys pubescens Forest of Tonggu County,Jiangxi Province as the research object.The data were obtained by standard site investigation and sample determination to analyse the effects of different canopy density(0.3-0.5,0.5-0.7,>0.7),slope position(up slope,middle slope,down slope)and their interaction on Polygonatum cyrtonema growth and soil physical and chemical properties.On the basis of clarifying the correlation between canopy density,slope position and soil and Polygonatum cyrtonema growth to select the suitable combination of canopy density and slope position.The results can provide a reference for large-scale cultivation of Polygonatum cyrtonema under Phyllostachys pubescens Forest in Tonggu County.The main results and conclusions are as follows:(1)There was a decrease in the growth indexes of Polygonatum cyrtonema with the increase of canopy density.Among them,the tuber fresh weight and tuber thickness under 0.3-0.5 canopy density were significantly higher than those with canopy density above 0.5(P<0.05).The tuber length under 0.3-0.5 canopy density was significantly longer than that under 0.5-0.7 canopy density(P<0.05).There was a trend of first decreasing and then increasing in soil moisture content,organic matter and total nitrogen which were in the same soil layer,while the soil bulk density increased first and then decreased,and the hydrolyzed nitrogen decreased gradually with the increase of canopy density.The soil bulk density,total nitrogen,total phosphorus,hydrolyzed nitrogen and available phosphorus were significantly different under different canopy density in 0-20 cm soil layer(P<0.05).The soil bulk density,total nitrogen,total phosphorus,organic matter and hydrolyzed nitrogen were significantly different under different canopy density in 20-40 cm soil layer(P<0.05).(2)The diameter and fresh weight of tubers on the middle slope were significantly larger than the other slopes(P<0.05).The tuber length of downhill was significantly higher than the other slopes(P<0.05).With the decrease of slope position,the soil bulk density of each soil layer was up slope>down slope>middle slope,and the soil water content was middle slope>down slope>up slope.The contents of total potassium and hydrolyzed nitrogen in soil increased with the decline of slope position.The soil water content,total nitrogen,total potassium,organic matter,hydrolytic nitrogen,available potassium and pH value were significantly different at different slope positions in 0-20 cm soil layer(P<0.05).The soil water content,total phosphorus,total potassium,organic matter,available potassium and available phosphorus were significantly different at different slope positions in 20-40 cm soil layer(P<0.05).(3)The interaction of canopy density and slope position had significant differences in ground diameter and tuber thickness(P<0.05),and had extremely significant differences in fresh weight and tuber width(P<0.01).The interaction between canopy density and slope position only had significant differences in pH value,total potassium and available potassium in 0-20 cm soil layer(P<0.05),but not significant in other soil physical and chemical indexes(P>0.05),the soil physical and chemical properties in 20-40 cm soil layer were not significant(P>0.05).(4)The correlation between soil water content and ground diameter,tuber fresh weight,tuber thickness,pH value and ground diameter,plant height,tuber fresh weight,tuber width and tuber thickness reached significant or extremely significant,the correlation between total nitrogen,hydrolytic nitrogen,organic matter and tuber fresh weight,tuber width,tuber length,tuber thickness of Polygonatum cyrtonema reached significant or extremely significant level,while there was no significant correlation between available phosphorus,available potassium,total phosphorus,total potassium and Polygonatum cyrtonema growth index.According to the correlation between Polygonatum cyrtonema growth indexes and soil physical and chemical indexes,five indexes including soil bulk density,pH value,total nitrogen,hydrolytic nitrogen and organic matter were selected,and the subordinate function values of soil physical and chemical indexes and Polygonatum cyrtonema growth indexes were calculated to evaluate the 9 canopy density and slope position combinations designed in this experiment.The results showed that the maximum value of average membership function was 0.769 when canopy density was 0.3-0.5 and slope position was downhill,which is most suitable habitat for Polygonatum cyrtonema planting under Phyllostachys pubescens forest. |
