Effects Of Planting Density On The Development And Dry Matter Accumulation Of Polygonatum.sibiricum Red.

Polygonatum.sibiricum Red.is a plant of the family Liliaceae.At present,the research on Polygonatum sibiricum is mainly focused on the chemical composition and pharmacological effects,while the research on high quality and high yield cultivation technology is less.This field density experiment was carried out under the pepper forest in Yangling.This experiment is to study the agronomic traits,accumulation and distribution of dry matter,yield,and the content of active ingredients(polysaccharides and saponins)of polygonatum sibiricum under different planting densities within a year in Yangling.In the meanwhile it may provide a theoretical basis for high yield and high quality production of polygonatum,and,at the same time,a new way for under-forest cultivation of Polygonatum.The results showed that in the range of tested densities,M4 treatment(35cm×30cm)was the most favorable circumstance for the growth of polygonatum sibiricum.The specific results are as follows:1.Effects of planting density on main agronomic characters and stress resistance of polygonatum: With the increasing of planting density,the plant height,stem diameter,maximum leaf length and leaf width,and new roots length of polygonatum were decreased.There were significant differences among the density treatments.The stem diameter was the highest in treatment of M4(35 cm×30 cm),which was 2.81 mm.The plant height,maximum leaf length and leaf width were the highest in treatment of M2 and M4,which were 15.71~16.52 cm,4.79~4.89 cm,and 0.58~0.60 cm,respectively.The new roots length was the highest in treatment of M2 and M3,which was 4.77~4.95 cm.The lodging rate increased with the increase of density,which was 9.26% in M3.When the density is higher than M3,the lodging rate increased significantly.2.Effects of planting density on dry matter accumulation of polygonatum: The effects of density on the growth of stem and leaf as well as the dry matter accumulation of the roots showed a certain regularity.There were significant differences among different treatments.The dry matter accumulation of stem and leaf per plant was the highest in the treatment of M2~M4,which was 6.58~6.95 g.Dry matter accumulation per plant and dry matter accumulation of rhizomes were the highest in M1~M4,which were 61.62~64.73 g and 55.05~57.98 g,respectively.3.Effects of planting density on yield of polygonatum: A reasonable population structure under favorable planting density is beneficial to increase crop yield.The planting density had a significant effect on the yield of polygonatum in this experiment.The yield increased with the improve of density,and then decreased with the improve of density after exceeding a certain density threshold.Yield production per unit area was the highest under M4(35 cm×30 cm),ending at 412.6kg/667 m2.The correlation between the yield per unit area and the growth index was not significant.Therefore,only a reasonable density,which coordinating groups and individual growth to reach the maximum dry matter accumulation in root through photosynthesis,could we obtain a high yield.4.Effects of planting density on the quality of polygonatum: The effects of planting density on the content of polysaccharides and saponins were significant.With the increase of density,polygonatum polysaccharides and saponins both showed a downward trend.The content of polysaccharides was the highest in the treatment of M3 and M4,which was 18.57%~19.01%.All treatment were much higher than the standard of pharmacopoeia.The content of saponins was the highest in the treatment of M1(45 cm×40 cm),which was 2.78%.But the decline rate of saponins was not much along with the increase of planting density,which can still reach 2.21% in M6.Besides,there was a significant negative correlation between saponins content and planting density.In summary,considering the yield and quality,the optimal planting density for polygonatum intercropping under pepper forest in Yangling is M4(35cm × 30cm).