| Leymus chinensis(Trin)is one of perennial pasture which belongs to Leymus Hochst,mainly distributed in northern China.L.chinensis has the advantages of high nutritional value,good palatability,resistance to cutting,trampling resistance,etc.,is an important forage grass in grassland.However,due to the arid climate,salinization of soil and overgrazing in recent years,large areas of grassland have been degenerated,seriously affecting the economic,social and ecological development of prairie region.L.chinensis is the main constructive species in Xilin Gol Grassland.The experiment was carried out in the restoration of degraded grassland plots in the Institute of Grassland Research of CAAS,Xilinhot.It tried to understanding the effects of single spraying 6-benzyladenine(6-BA),urea,potassium dihydrogen phosphate and their compound spraying treatments on the growth and physiological characteristics of L.chinensis.The suitable treatment concentration and method were screened out,which laid the foundation for exploring its mechanism of action and played an exemplary role in the restoration of grassland productivity.The main results are as follows: 1.Effect of 6-BA on growth and physiological characteristics of L.chinensis under field conditionsThe experiment was carried as randomized blocks design,plot area is 20m×20m,spraying concentration were 5mg/L,25mg/L,and 50mg/L,pure water treatment was control.Research shows that three concentrations of 6-BA treatment could promote the growth of L.chinensis.The contents of soluble sugars,soluble protein,free amino acids and phosphorus and the activities of glutathione reductase(GR)were the highest at 50mg/L 6-BA,the contents of malondialdehyde(MDA)and leaf electric conductivity were the lowest at 50mg/L 6-BA.The plant height,root / shoot ratio,dry and fresh weight,content of chlorophyll-a,chlorophyll-b,total photosynthetic pigments,nitrogen,value of chlorophyll a/b,the activity of superoxide dismutase(SOD)and catalase(CAT)were the highest at 25 mg / L 6-BA;carotenoid content was the highest at 25 and 50 mg / L 6-BA;potassium content and ascorbate peroxidase(APX)activity were highest at 5 mg / L concentration of 6-BA.The results showed that 6-BA at 25 mg / L had the best effect on the growth of L.chinensis,followed by 50 mg / L 6-BA.2.Effect of urea on growth and physiological characteristics of L.chinensis under field conditionsThe spraying concentrations of urea in L.chinensis were 1%,2% and 3% respectively.The results showed that the growth of L.chinensis was promoted in different degrees after three concentration of urea treatment.The activity of APX was the highest at 1% urea;root / shoot ratio,soluble sugar content,soluble protein content,potassium content,SOD activity,POD activity and CAT activity were highest at 2% urea;plant height,fresh weight,dry weight,chlorophyll-a content,chlorophyll-b content,total photosynthetic pigments content,MDA content,leaf electric conductivity,nitrogen content,phosphorus content and GR activity were the highest at 3% urea;chlorophyll a/b reach to peak at 1% and 3% urea.In a summary,the effect of spraying 3% urea on the growth of L.chinensis was the best,followed by the spraying 2% urea.3.Effect of potassium dihydrogen phosphate on growth and physiological characteristics of L.chinensis under field conditionsThe growth of L.chinensis was promoted by spraying potassium dihydrogen phosphate at concentrations of 0.5%,1% and 2% on L.chinensis.The results showed that root/shoot ratio,fresh weight,dry weight,chlorophyll-b content,total photosynthetic pigments,MDA content,soluble sugar content,soluble protein content,free amino acids and chlorophyll a,chlorophyll a/b,leaf electric conductivity,nitrogen content,potassium content and SOD activity after foliar sprayed with 1% potassium dihydrogen phosphate POD activity,CAT activity and APX activity were the best.Phosphorus content was the best when foliar sprayed with 0.5% potassium dihydrogen phosphate.Comprehensive analysis shows that foliar application of 0.5% potassium dihydrogen phosphate in the field conditions to promoted the growth of L.chinensis best,1% potassium dihydrogen phosphate foliar spray treatment effect second.4.Effect of compound spraying 6-BA,urea,potassium dihydrogen phosphate on growth and physiological characteristics of L.chinensis under field conditionsOn the basis of the above experiments,compound spraying 6-BA,urea and potassium dihydrogen phosphate studies were carried out.Studies have shown that compounding further promoted the growth of L.chinensis.The results showed that the root/shoot ratio,fresh weight,dry weight,chlorophyll-a content,chlorophyll-b content,chlorophylla/b,the contents of soluble sugar,soluble protein,free amino acid,nitrogen,the activity of SOD,POD and CAT were the highest.After spraying with 25 mg / L 6-BA + 3% urea,the plant height,activity of GR enzyme had the best effect.The effect of spraying 25 mg / L 6-BA + 0.5% potassium dihydrogen phosphate on carotenoid content,total photosynthetic pigments,leaf electric conductivity,phosphorus content,potassium content and APX activity were the best.According to the comprehensive analysis,among all treatments,25 mg / L 6-BA + 3% urea + 0.5% potassium dihydrogen phosphate proved to have the best effect on promoting the growth and improving the stress resistance of L.chinensis. |
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