Effect Of Potassium Salt On Growth And Product Synthesis Of Seedlings For Discorea Nipponica

Dioscorea nipponica is a traditional medicinal plant.In this paper,the seedlings of D.nipponica in the source of Guandi Shan were used as test materials,KNO₃,K₂SO₄ and KCl with potassium salt concentrations of 2,4,6,8 and 10 mmol·L^-1,were respectively applied.The morphological diversity of this species in different periods under different potassium salt concentrations was analyzed.The chlorophyll,sugar content and metabolite content of leaves in different potassium concentrations and different periods were compared.The content of diosgenin,the active constituent of rhizome under different potassium salt concentrations,was determined.The content of diosgenin,the active constituent of rhizome under different potassium salt concentrations,was determined.Based on the above results,it provides a scientific basis for the cultivation of D.nipponica.The main conclusions were as follows:?1?Plant morphologyWhen the potassium salt was KNO₃ and K₂SO₄,the plant height,branch number,leaf length,leaf width and leaf area maximum of the D.nipponica were all at 8 mmol·L^-1.When KCl was applied,the above indexes were at a maximum concentration of 6 mmol·L^-1,and increased rapidly before treating for 120 days,and increased relatively slowly after 120 days;The leaf aspect ratio and leaf base angle were not significant between different concentrations of potassium salt;the biomass of aboveground and underground parts were significant at each potassium salt concentration.?2?The content of chlorophyll in leafThere were significant differences in Chl a concentration and chlorophyll content between different potassium salt concentrations.The concentration of Chl a and the chlorophyll content of the leaves of KNO₃ and K₂SO₄ were the highest at 8 mmol·L^-1.When KCl was applied,the maximum value appeared at 6 mmol·L^-1,and KNO₃>K₂SO₄>KCl between the three potassium salts.During the treatment of potassium salt,the concentration of Chl a and the content of chlorophyll continued to increase,and then decreased rapidly;There was no significant effect on the concentration of Chl b and Chl a/Chl b in different potassium salt concentrations.?3?The content of sugar in leafThere were differences in the content of sugar in leaf between different potassium salt concentrations: When treated for 60 d,the content of soluble sugar,glucose and reducing sugar in the leaves of D.nipponica had significant differences and showed a trend of increasing first and then decreasing;After treating 120 d,as potassium salt concentration increased,the trend of soluble sugar decreased first and then increased.The other treatments increased or decreased slightly,and the change trend of glucose content tended to be gentle;When treated for 180 d,the changes of soluble sugar and reducing sugar content decreased first and then increased,and the optimum potassium concentration was KNO₃<K₂SO₄<KCl.There was no change in the concentration of reducing sugar content,but the overall content decreased significantly compared with 60 d.?4?The metabolite content in leafThe change trend of the pyruvic acid content of the leaves before the treatment for 120 days showed a trend of increasing first and then decreasing with the increase of concentration,and then showing the parabolic trend with the opening upwards.Different potassium concentrations also had significant effects on the content of diosgenin in rhizomes,and the content was the highest when 8 mmol·L^-1KNO₃ and K₂SO₄ were applied.The highest content of saponin was observed at the concentration of 6 mmol·L^-1 when KCl was applied.Compared with the three potassium salts,KNO₃>K₂SO₄>KCl.?5?Correlation between the above indicators and the content of diosgenin in rhizomePlant height,branch number,leaf length,leaf width,leaf area,aboveground and underground biomass and other growth indicators,chlorophyll,soluble sugar,glucose,reducing sugar,pyruvic acid and other physiological indicators and rhizome diosgenin content significantly related,can be used as an indicator to judge the quality of the radix.In summary,the characteristics of integrated plant morphology,leaf chlorophyll content,leaf sugar content,leaf metabolite content and rhizome saponin content,The available plant height and leaf area can be used as the preferred morphological indicators for the screening of the germplasm resources of D.nipponica;Considering the effect of potassium salt and concentration on the seedlings of D.nipponica,8 mmol·L^-1KNO₃ and K₂SO₄ salts had the best effect on improving the yield and quality of D.nipponica,which can provide a scientific basis for artificial planting of D.nipponica.