Effect Of Seedling Size And Transplanting Density On Productive Property Of Codonopsis Pilosula

Seedlings are the material basis for Codonopsis pilosula cultivation,because the different seedlings size have different selectivity and adaptability to transplanting density.Therefore,in the experiment,the seedlings were divided into four grades:big seedling,middle seedling,small seedling and slender small.the densities of 625000 plant·hm^-2,500 000 plant·hm^-2and 416 700 plant·hm^-2were used to transplant respectively.Each treatment were comprehensively evaluated by measuring agronomic traits,physiological characteristics,yield and quality of medicinal materials in order to select the best planting conditions.It provides a theoretical basis for high-yield and high-quality planting of C.pilosula in Gansu.The research results are summarized as follows:1.In general,in different densities,the rate of returning green decrease with the decrease of seedlings.The allometric growth trend of different sizes seedlings was obvious after returning green.And the allometric traits were greatly affected by the seedlings size.The growth potential of big seedlings and middle seedlings decreased with the delay of the growth period,however,small seedlings and slender seedlings increased.2.seedlings size and transplanting density had a significant impact on the physiological characteristics of C.pilosula leaves,and the activity of antioxidant enzyme varies significantly with the growth and development of C.pilosula and the season.In C.pilosula daylight synergy,from 9:00 to 11:00,the net photosynthetic rate of each treatment showed an increasing trend,and 11:00 to 19:00 showed a downward trend.3.Seedlings size and transplanting density had a obviously impact on the yield of C.pilosula medicinal materials.The yield of middle seedlings at the density of 625000 plants·hm^-2was significantly higher than that of big and slender seedlings.Under different densities,the root length of big and middle seedlings were better than small and slender seedlings,the same as their incidence and disease index were also higher.Big seedlings had high yield of medicinal materials at lower density,and the result were opposite to middle,small and slender seedlings.Different treatments had no significant differences in thousand-grain weight,but had significant differences in seed yield.4.Seedling size and transplanting density had a significant interaction on the active ingredients of C.pilosula.At the density of 416 700 plant·hm^-2,the polysaccharide content of big,middle and slender seedlings was the highest;big and middle seedlings had the highest alkynyl glycoside content in the density of 625 000plant·hm^-2and slender seedlings at 416 700 plants·hm^-2;big and small seedlings in625 00 plants·hm^-2and middle and slender seedlings in 500 000 plants·hm^-2had the highest extract content.Seedlings of different sizes had the highest water content under the density of 500 000 plants·hm^-2.5.The comprehensive factor analysis of 15 traits including agronomic traits,disease resistance,and medicinal materials yield and quality of C.pilosula showed that big seedlings the best cultivated density was 416 700 plants·hm^-2,middle seedling and small seedlings was 625,000 plants·hm^-2,and slender seedlings in each density was poor.