Research On Photosynthetic Characteristics And Water Consumption Of Polygonatum Sibiricum Red.

The root of Polygonatum sibiricum Red.is one of the Chinese Materia Medica.With the increase of the demand for Polygonatum sibiricum Red.and the decrease of wild resources,more and more areas began to cultivate it artificially.In order to ensure the stable quality,effectively improve the yield,and make the production and cultivation of Polygonatum sibiricum Red.more scientific and standardized,the critical technique of standardizing planting must be studied.In this paper,the photosynthetic rate of leaves with different leaf positions and the influence of environmental factors on photosynthetic rate,the effects of different moisture conditions on the water consumption characteristics,growth,physiological characteristics,yield and active components content of Polygonatum sibiricum Red.were systematically studied.And the field irrigation and drainage system has been preliminary established.The results are expected to provide theoretical basis and technical support for yield enhancement and standardized cultivation.The main results are as follows:1.There was a significant difference in Pn as the middle leaf layer>the upper leaf layer>the lower leaf layer,and the leaf photosynthetic rate presented“low-high-low”tendency with the increase of leaf position;The net photosynthetic rate in different leaf pos-itions for Polygonatum sibiricum Red.appeared in curvilinear changes with double peaks and apparent middy depression diurnally;Stomatal limitation was the key factor for different time intervals influencing photosynthesis,while non-stomatal limitation was the major factor of influencing photosynthesis for different position leaves;The analysis showed that RH was the primary determining factor,and the response of leaves to environmental factors was different at different leaf positions.In the hot noon,the RH can be appropriately increased to improve the photosynthetic efficiency.2.The water consumption of Polygonatum sibiricum Red.is different under different water content.During the whole growth stage of 100d,under 50%?f,70%?f and 85%?f soil water treatment,the water consumption was 5.090 kgH₂O,6.791 kgH₂O,7.733 kgH₂O per plant.The water consumption in the whole growth period was small in the early stage,large in the middle stage and small in the late stage.Water-consumption in August was more than 40%of whole,which was the water consumption peaks.Diurnal dynamics of water consumption are unimodal curves,and there is a significant difference as 85%?f>70%?f>50%?f.3.The growth and physiological indexes of Polygonatum sibiricum Red.were different under different soil moisture conditions.The plant height,stem diameter,leaf length and leaf width of Polygonatum sibiricum Red.seedlings treated with irrigation once a month were significantly higher than those of other treatment groups.In the period of root swelling,irrigation once or twice a month is more beneficial to the root growth,and too little or too much water will limit the root growth.The decrease of soil water content will result in the decrease of leaf area and specific leaf area,and increase of specific leaf weight.In addition,the content of chlorophyll,proline,soluble total protein and soluble total sugar content in leaves increased significantly in the treatment with 50%?f and 70%?f.4.Different soil moisture conditions also have great influence on the yield and effective component content of Polygonatum sibiricum Red..From July to September,under different soil water conditions,the yield of Polygonatum sibiricum Red.showed that:twice a month>three times a month>once a month>non-irrigation.The biomass accumulation peak was in October,and the non-irrigation treatment group was significantly higher than the other treatment groups.The middle and late September was the critical period for polysaccharide accumulation,and moderate drought in soil water?A1?was beneficial to polysaccharide accumulation.During the whole growing period,higher soil water content was beneficial to the increase of root-crown ratio,which meant more organic substances were distributed to the root system.And it was beneficial to the economic yield.Lower soil water content?50%?f?facilitates the rearrangement of dry matter to new rhizomes.Therefore,in field production,it is suggested that sufficient water should be provided in the early stage to meet the nutritional growth of Polygonatum sibiricum Red.,and appropriate drought stress should be carried out in the later stage to increase the polysaccharide content,and the harvest should be completed before the end of October to ensure the yield.5.Based on water requirement law of Polygonatum sibiricum Red.,rainfall,air temperature of Lueyang,the irrigation system was advanced:In the early stage of growth,the soil water content was lower than 13.17%;in the period of root swelling,the soil water content was lower than 18.43%;in the late stage,the soil water content was lower than13.17%,irrigating tamely.When the soil moisture content exceeds 22.38%,timely drainage should be carried out.The irrigation and drainage water should be determined by comprehensive consideration of the current year's rainfall and other factors.