Effects Of Exogenous Polyamines On Flower Bud Differentiation And Stress Resistance Of Anoectochilus Roxburghii

Anoectochilus roxburghii(Wall.)Lindl.is a rare and precious medicinal plant in China,which has the medicinal,food tonic and ornamental function at the same time.Polyamines are plant growth regulators,their metabolic changes are closely related to the growth and development of higher plants.The effects of exogenous polyamines on flower bud differentiation,drought resistance and salt tolerance of A.roxburghii were studied in this paper,the aim is to provide a theoretical basis for improving the adaptability to adverse environment,and then expanding the planting,increasing the yield and finally obtaining high quality of A.roxburghii.The main results are as follows:1.Compared the effects of three different concentrations(0.03,0.3,3 mmol/L)of Put,Spd and Spm on flower bud differentiation of A.roxburghii,the results showed that exogenous polyamines advanced the florescence of A.roxburghii,and significantly increased the fresh weight,pedicel length,soluble protein concentration,activities of antioxidant enzymes(SOD,POD,CAT),contents of endogenous polyamines(Put,Spd,Spm)and main active components(polyphenols,polysaccharides,flavonoids),reduced the accumulation of MDA and H2O2 in plants.Among them,3 mmol/L Put and 0.3 mmol/L Spd or Spm were more effective,which advanced the florescence of A.roxburghii by 8,14 and 16 days,increased the content of total active components(polyphenols + polysaccharides + flavonoids)by 28.07%,31.65% and 23.41%,respectively.2.Studied the effect of exogenous Spd on drought resistance of A.roxburghii,the results showed that drought stress significantly inhibited the growth of A.roxburghii,and decreased the activities of antioxidant enzymes and key enzymes of polyamine metabolism,while the content of H2O2,MDA and the REC of leaves increased by 68.84%,103.61% and 63.64%,respectively.Under drought stress,foliar spraying Spd(0.5 or 5 mmol/L)effectively promoted the growth of fresh weight,plant height and stem diameter,reduced various adverse reactions,significantly enhanced the activities of protective enzymes,and decreased the REC and the accumulation of MDA and H2O2.Spd of 0.5 mmol/L was better than that of 5 mmol/L.3.The effects of exogenous Spd on salt tolerance of A.roxburghii were studied,the results showed that salt stress significantly inhibited the growth of plant height,fresh weight and stem diameter,decreased chlorophyll contents and protective enzymes activities,and significantly increased the REC,MDA and PRO contents.Under salt stress,foliar spraying Spd(0.3 mmol/L)effectively promoted the growth of plant height,significantly increased chlorophyll contents,decreased leaf REC and MDA accumulation,thus alleviated the peroxidation damage of plasma membrane caused by salt stress,and enhanced the antioxidant capacity of A.roxburghii.Compared with simple salt stress,spraying Spd increased the activities of protective enzymes by 49.57%(SOD)and 50.72%(CAT),respectively.