Effects Of Planting Density On The Growth And Effective Constituent Accumulation Of Glycyrrhiza Uralensis And Its Mechanism

Reasonable planting density plays an important role on the high yield and high quality of medicinal plants.In order to improve the yield and quality of cultivated Glycyrrhiza uralensis Fisch.,this test,through the field planting density test,carries out comparative studies on the growth characteristics,population photosynthetic characteristics,canopy structure,ecological functions of different leaves,by the examples of the artificial cultivated G.uralensis population in Glycyrrhiza protection and rejuvenation base in Hutubi County,Changji Prefecture,Xinjiang Uygur Autonomous Region.The purpose of this test is to expound the effects of different planting densities on the yield and effective constituent accumulation of G.uralensis,and to reveal the correlation between photosynthetic capacity and biological characteristics of G.uralensis under different cultivation densities.The mechanism that density control affects the growth and development of G.uralensis will be also discussed,which can help select suitable planting density for the growth and development of G.uralensis,provide scientific basis for the high quality and high yield of artificial planted G.uralensis and provide theoretical basis and technical guidance for the construction of G.uralensis GAP base.The main research results are as follows:1.Density control has an important effect on the growth and development of the part of Glycyrrhiza uralensis above ground and underground.G.uralensis as medicinal plant with rhizome being used as medicine,its economic values mainly focus on the roots,so the growth and development of G.uralensis root system directly affects its yield and quality.The planting density has no significant effect on the growth and development of root and root shoot ratio of the G.uralensis in first growth year.Comparing G.uralensis in second growth years under different planting densities,the root shoot ratio of single G.uralensis under medium density(360,000 per hectare)and low density(240,000 per hectare)is significantly higher than that of G.uralensis in first growth year.The root shoot ratio of G.uralensis under medium density is highest,indicating that the G.uralensis growing under this condition can allocate more energy to the roots.However,the single plant of G.uralensis under low density grows the most vigorous,which not only can improve the quality of the appearance of medicinal part of G.uralensis,but also can allow the energy distribution of aerial part and underground part to reach the optimal state,while achieving high yield and high quality of G.uralensis planting.2.Density control has a significant impact on the yield and quality of Glycyrrhiza uralensis.Density control has a certain effect on the quality of single plant of G.uralensis in first growth year,but slightly affects its yield.However,the effect of planting density on the accumulation of dry matter in G.uralensis roots becomes more and more obvious in second growth years,with the continuous growth of ground and underground vegetative organs.It can be seen that the dry matter accumulation in root of planted G.uralensis growing under the condition of high density is not dominant(480,000 per hectare).However,in the medium and low density cultivation conditions,the single root shoot ratio of G.uralensis increases significantly(P < 0.05),which allows the G.uralensis to get the growth tendency of high quality and high yield.The effects of this planting densities on the average content of total flavonoids in G.uralensis are not significant.However,both medium and low densities can contribute to the formation and accumulation of acid in the roots of G.uralensis,and ensure the officinal quality of G.uralensis to peomote steadily year by year.3.Analysis the mechanism of planting density affecting on the yield and quality formation of Glycyrrhiza uralensis.Photosynthesis is the material basis of the yield formation of cultivated crops.The accumulation of effective photosynthate is negatively correlated with the planting density.Medium-density and low-density G.uralensis groups all show higher photosynthetic efficiency in the second year,which provids material basis for the increase of yield.With the increase of growing year,the photosynthetic capacity of G.uralensis groups under high-density show a significant decline in photosynthetic capacity due to the increase in canopy respiratory rate(CR).Under the condition of close planting,the internal side of G.uralensis group is seriously covered and the utilization rate of light energy is significantly decreased.The photosynthetic capacity of different leaf layers is closely related to their height while the difference of anatomical structures in different leaf parts is mainly connected to the light environment of leaves.Specifically,the results show that the leaves of the upper leaf layer,which the chlorophyll content is higher,the palisade tissue is the most closely,and the total canopy apparent photosynthesis(TCAP)is the highest,but the canopy apparent photosynthesis(CAP)is significantly lower than that of the middle leaf layer.For the leaves in the middle leaf layer,which the structural development is more mature,the chlorophyll content is high and the respiration rate is the lowest,so the light energy utilization ability of the middle leaf layer is high.And the leaves of the lower leaf layer show typical shade structure with increased leaf thickness,loose palisade tissue,flourishing spongy parenchyma,the highest ash content and the lowest chlorophyll content.