Study On The Optimum Regulation Mechanism Of Isatis Indigotica Fort. Cultivation Techniques

Isatis indigotica Fort.is the basic plant of Radix Isatis and Folium Isatidis.Minle County of Gansu Province is‘Origin site of Radix Isatis in China'.In recent years,the yield and quality of medicinal materials have declined due to the non-GAP cultivation techniques with Isatis indigotica.The effect of yield determinants and cultivation techniques on the growth,yield and quality of Radix Isatidis were systematically studied by field plot experiments and laboratory measurements.Results showed that the intrinsic relationship between cultivation factors and biomass,physiology and biochemistry,photosynthetic characteristics,yield and quality were explored,the regulation mechanism of cultivation techniques on the growth,photosynthesis,physiology and biochemistry of Isatis indigotica was revealed.The optimal regulation scheme of Isatis indigotica cultivation technology was determined and provided a theory foundation for the optimal cultivation techniques of Isatis indigotica in Minle County,Gansu Province.The specific findings were as follows:1.Studies on agronomic traits affecting the yield of Radix Isatidis showed that the agronomic traits of Isatis indigotica were rich in variation that the coefficient of variation ranged from 9.83%to69.22%.The variation coefficients of root fresh weight,leaf fresh weight and leaf area were all greater than 60%.The variation coefficients of root yield were greater than 50%.However,the variation coefficients of root diameter,leaf dry matter content,root length and root dry matter content were smaller.Correlation analysis,stepwise regression analysis and path analysis were used to establish a regression equation between Radix isatidis yield?y?and root length?x₁?and root fresh weight?x₂?:y=0.497x₁+0.104x₂-5.981,and decision-making coefficients for determining root length and fresh weight were 0.837 and 0.592.According to the decision coefficient,the main determinant of yield formation of Isatis indigotica Fort is root length,and the secondary determinant is root fresh weight.2.The sowing date study showed that the highest yield of Radix isatidis was 5000.25 kg·hm^-2on April 22 and the lowest was 4066.87 kg·hm^-2 on May 22.The content of Epigoitrin?0.073%⁰.083%?was high if sowing dates from April 22 to May 12.Other sowing dates were low?0.056%⁰.063%?.The suitable sowing period for Isatis indigotica is from late April to early may.3.The density of cultivation indicated that individual plant biomass,yield components,net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs?and intercellular CO₂concentration?Ci?of Isatis indigotica were the best when row spacing was 25 cm and plant spacing was 10 cm.The yield of Radix isatidis was the highest,5208.89 kg·hm^-2;The quality was the best and the content of Epigoitrin was the highest and reached 0.082%.Principal component analysis showed that Tr and WUE were the main photosynthetic indexes of Isatis indigotica affected by cultivation density.In Minle County,Isatis indigotica was cultivated with row spacing of 25 cm,plant spacing of 10 cm and planting density of 400 200 plants per hm^-2.4.The cultivation method of Isatis indigotica indicated that the ridge was covered with black membrane,the root has the longest growth period,the root system was the most developed,and the root length,root diameter and root dry weight were best.The yield of Radix Isatidis was the highest(4514.4 kg·hm^-2),the content of Epigoitrin was the highest?0.261%?with white film mulching and non-mulching was the lowest?0.137%?.The main root length,root diameter and root dry weight growth of Isatis indigotica under ridge cultivation and black film mulching showed a‘S'growth trend with the growth time,which accorded with the Logistic growth model.The equations were as follows:RL_t=22.78/(1+e^2.78-0.042t),RD_t=1.23/(1+e^3.13-0.044t),RDW_t=7.52/(1+e^5.91-0.071t).The suitable cultiva-tion method of Isatis indigotica in Minle County is ridge cultivation and mulching with black film according to the yield of Isatis indigotica and the content of Epigoitrin.5.Irrigation research showed that the period from seedling stage to rosette stage was the maximum period when the water consumption of Isatis indigotica was between 365.99⁵38.02 mm.The utilization of Isatis indigotica in soil moisture is mainly concentrated in the soil layer of 40-60cm.Soil water supply capacity gradually decreased,root length became shorter,root diameter,number of lateral roots,dry fresh weight increased,and refraction rate decreased with the increase of amount of irrigation.Ci and Tr were the main indexes affecting photosynthetic characteristics of Isatis indigotica under irrigation.The yield,water use efficiency and the content of Epigoitrin of Radix Isatidis were the highest in treatment W₂?total irrigation was 135 mm at seedling and lotus stage?.The yield was5125.87 kg hm^-2 and 5895.87 kg hm^-2,with the content of Epigoitrin 0.0592%of Radix Isatidis.Yield-water response value?Ky?was 0.77,and the seedling stage,rosette stage and succulent root swelling stage were 0.62,0.5 and 0.44,respectively.The suitable scheme irrigated each time at“seedling stage+lotus stage".Each time was 67.5mm(675 m³·hm^-2),the total amount was135mm(1350 m³·hm^-2).6.Fertilization research showed that the main fertilizer factors limiting the growth of Isatis indigotica were nitrogen and potassium.Gs,WUE and Tr were the main indicators of the effects of fertilization on the photosynthetic characteristics of Isatis indigotica.The main indicators affecting the characteristics of physiological and biochemical indicators were chlorophyll SAPD value and SOD.The yield of Radix Isatidis increased by 11.73 kg,3.63 kg and 19.56 kg,respectively for every1kg of nitrogen,phosphorus and potassium.The optimum ratio of Nitrogen,phosphorus and potassium was N:P₂O₅:K₂O=1:0.42:0.63.Nitrogen,phosphorus and potassium fertilizers all have effects on agronomic traits,photosynthetic characteristics,physiological and biochemical indexes,yield and quality of Isatis indigotica.The recommended fertilization rates of N,P₂O₅ and K₂O were222.95²54.44 kg,96.01¹02.89 kg and 148.44¹51.38 kg,respectively to aim at the yield of8274.88⁸502.14 kg per hectare of Radix isatidis.7.The best harvesting period study showed that the dry weight of Isatis indigotica root showed an‘S'-type change trend with the growth days,which accorded with the Logistic growth model.The equation was y=11.606/(1+e ^{3.385-0.0301x})?R²=0.9506,p<0.01?;The yield was the highest in November,and the yield per plant reached 9.79-9.96g;The content of Epigoitrin was the lowest on October 12,about 0.008%and the highest on November 12,reached 0.083%,and significantly higher than other harvesting periods.The optimum harvest time of Radix Isatidis in Minle County was in early November according to the yield and Epigoitrin content.