| Kenaf contains a variety of flavonoids,and many articles have reported that flavonoids have many effects such as antioxidant,hypolipidemic,anti-fatigue and so on.However,there are few reports about the use of ephedrine in actual production,which greatly limits the application of kenaf.Therefore,this experiment hopes to obtain the best cutting method by optimizing the extraction of kenaf total flavonoids and the effect of different cutting methods on the total flavonoid content of kenaf to provide technical support for the use of kenaf forage.The main conclusions are as follows:(1)The single factor test and response surface test were used to study the four factors that affect the extraction volume of kenaf total flavonoids,ethanol volume fraction,reaction temperature,reaction time,and liquid-to-material ratio.The best extraction process obtained by single factor is:ethanol volume fraction 80%,reaction temperature 80°C,reaction time 2 h,liquid-to-material ratio 30:1(m L/g).Response surface optimization extraction process:ethanol volume fraction 79.88%,reaction temperature 80.21°C,reaction time 2.03 h,liquid-to-material ratio 30.43:1(mL/g),the two results are basically the same.For convenience of experiment,we choose experimental conditions as that:ethanol volume fraction 80%,reaction temperature 80°C,reaction time 2 h,liquid-to-material ratio 30:1(mL/g).Three verification tests were carried out under the best extraction process,and the extraction amount of flavonoids in kenaf was 2.427 mg/g,2.516 mg/g,2.431 mg/g,and the average value of three parallel tests was 2.458 mg/g.Comparing with the predicted value of the surface model 2.396 mg/g the error is 2.52%.Therefore the optimal extraction process parameters obtained by the response surface test are stable and reliable,and can be applied to the extraction of total flavonoids from kenaf.(2)Through the preliminary experiment of the research group,we have selected 6 kenaf varieties(labeled K1,K2,K3,K4,K5,K6 for statistical purposes),and explored the differences in yield traits and total flavonoids content of kenaf at 70,130 and 160 days of growth.When analyzing the dry matter yield and total flavonoids content in different sampling periods.It was found that:dry matter yield at160 days in the growth phase>dry matter yield at 130 days in the growth phase>dry matter yield at 70days in the growth phase,and the dry matter yield of variety K1 was all in the three sampling periods highest.At 70 days of growth,K6 leaf total flavonoids content(2.647 mg/g)>K3 leaf total flavonoids content(2.528 mg/g)>K6 leaf total flavonoids content(2.342 mg/g)>K5 leaf total flavonoids content(2.289 mg)/g)>K4 leaf total flavonoids content(2.185 mg/g)>K1 leaf total flavonoids content(2.108mg/g).At 130 days of growth,K4 leaf total flavonoids content(4.788 mg/g)>K6 leaf total flavonoids content(4.125 mg/g)>K5 leaf total flavonoids content(3.817 mg/g)>K3 leaf total flavonoids content(3.595 mg/g)g)>K1 leaf total flavonoids content(3.510 mg/g)>K2 leaf total flavonoids content(3.245mg/g).At 160 days of harvest,K4 leaf total flavonoids content(1.986 mg/g)>K6 leaf total flavonoids content(1.912 mg/g)>K1 leaf total flavonoids content(1.733 mg/g)>K2 leaf total flavonoids content(1.686 mg/g)g)>K5 leaf total flavonoids content(1.651 mg/g)>K3 leaf total flavonoids content(1.521mg/g).The total flavonoids content in the growth period of 130 days was significantly higher than that of the growth period of 160 days and the growth period of 70 days.Therefore,the growth period of 130days was selected as the best harvest period of kenaf.(3)According to the preliminary experiment of the research group,the 6 varieties tested were treated as follows:kenaf plants with a growth period of 70 days and approximately similar physiological indicators were selected for cutting,and the stubble height was 90 cm,120 cm,and 150cm.During the 160 days harvest period,the total flavonoids and nutrient contents of each kenaf variety and different stubble patterns were measured,and the changes of total flavonoid content of different varieties before and after cutting were compared.Through analyzing the data,in exploring the influence of different stubble heights on dry matter yield traits,the trend of dry matter yield is:stubble height120cm>stubble height 150cm>stubble height 90cm.When the stubble height is 120 cm,K1 total dry matter yield(4549.00 kg/hm~2)>K6 total dry matter yield(4176.88 kg/hm~2)>K4 total dry matter yield(4014.39 kg/hm~2)>K5 total dry matter yield(3959.02 kg/hm~2)>K3 total dry matter production(3881.98kg/hm~2)>K2 total dry matter production(3671.43 kg/hm~2).The trend of total flavonoids content is:stubble height 120 cm>stubble height 150 cm>stubble height 90 cm.K4 total flavonoid content(2.137mg/g)>K2 total flavonoid content(1.940 mg/g)>K5 total flavonoid content(1.873 mg/g)>K1 total flavonoid content(1.786 mg/g)>K3 total flavonoid content(1.665 mg/g)>K6 total flavonoid content(1.647 mg/g).The trend of total leaf crude protein content is:stubble height 90 cm(13.62%?20.67%)>stubble height 120 cm(11.57%?18.70%)>stubble height 150 cm(11.51%?18.52%).Protein content(11.96%?20.53%).When the stubble height is 90cm,K3 leaf crude protein(20.67%)>K2 leaf crude protein(19.15%)>K5 leaf crude protein(18.38%)>K6 leaf crude protein(16.63%)>K4 leaf crude protein(15.72%)>K1 leaf crude protein(13.62%).The crude fiber content of the whole leaf is the stubble height of 90 cm(16.06%-20.81%),the stubble height of 120 cm(15.71%-17.97%),and the stubble height of 150 cm(14.57%-19.68%).Fiber content(18.22%?25.64%).When the stubble height is 120 cm,variety K4 has the largest crude fiber content(17.00%),and variety K1 has the smallest crude fiber content(13.34%).The crude fiber content of the whole stem is 90 cm(30.93%?39.17%)of stubble height,120 cm(37.28%?42.72%)of stubble height,and 150 cm(39.32%?45.92%)of stubble height.Fiber content(41.09%?46.02%).When the stubble height is 120 cm,variety K4 has the largest crude fiber content(42.46%),and variety K3 has the smallest crude fiber content(38.00%).Kenaf is used as feed in actual production,and crude protein content and crude fiber content should be used as the main inspection indicators.Integrating the four factors of dry matter yield,total flavonoid content,crude protein content and crude fiber content on kenaf.Among the 6 varieties tested,K3 was the best variety.When the stubble height was 120 cm,it had the largest crude protein content(20.67%),and the smallest crude fiber content(38.00%),and the total flavonoid content(1.665 mg/g),and the total dry matter production(3881.98 kg/hm~2). |
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