Study On The Effect Of Plant Growth Regulators On The Growth Of Sphagnum Palustre Under Different Water Gradient Conditions

Sphagnum,due to its high commercial value,has been mined in large amounts.Sphagnum wetland has been negatively affected by global warming and especially by drought in summer,which have caused subtropical mountain sphagnum wetlands to be severely damaged.In order to restore sphagnum wetlands and accelerate the reproduction of sphagnum,artificial planting of sphagnum has become an alternative.At present,there are still few researches on the effects of plant growth regulators on the growth of Sphagnum palustre L.,a dominant species in subtropical mountain sphagnum wetlands.In this study,the subtropical mountain S.palustre was used as the research object,and 3 water gradients were set:(water application 5ml,7.5ml,10ml);4 kinds of plant growth regulators:indole acetic acid(IAA),naphthalene Acetic acid(NAA),gibberellin(GA₃),6-benzyl adenine(6-BA);4 concentration gradients:0.1mg/L,1mg/L,10mg/L,100mg/L.Spraying control experiments were carried out to explore the effects of different types and concentrations of plant growth regulators on the growth of S.palustre and its internal mechanism under different water gradient conditions.The results of the study are as follows:(1)Spraying plant growth regulators under different water gradient conditions can significantly promote the growth of S.palustre.Under different water gradients,compared with the control group,the sprayed reagent group had a significant promotion effect on the branch length,the number of capitula,the coverage and the biomass of S.palustre.(2)Under normal water conditions and slight drought stress:under IAA(100mg/L),NAA(1 mg/L),GA₃(10mg/L),6-BA(0.1 mg/L)concentration treatments,The effect of S.palustre growth is the best.Under severe drought stress:under IAA(100mg/L),NAA(0.1 mg/L),GA₃(1mg/L),6-BA(0.1 mg/L)concentration treatment,the effect on the growth of S.palustre can reach optimal.(3)Under normal water conditions,among the eight physiological indicators of S.palustre(TN,TP,TK,N:P,N:K,P:K,total chlorophyll,soluble sugar),TN is the most important factor affecting the productivity of S.palustre,The regression model is:Y=-0.029*TN+0.506,(R²=0.413,P<0.001).Within the scope of this study,when the TN content of S.palustre was greater than 6.8 mg/g,the growth of S.palustre was restricted.Under mild drought stress,among the eight physiological indicators(TN,TP,TK,N:P,N:K,P:K,total chlorophyll,soluble sugar),TP is the most important factor affecting the productivity of S.palustre.The regression model is:Y=-0.116*TP+0.349,(R²=0.172,P<0.01).Under severe drought stress,among the eight physiological indicators(TN,TP,TK,N:P,N:K,P:K,total chlorophyll,soluble sugar),N:K is the most important factor affecting the productivity of S.palustre,The regression model is:Y=-0.029*(N:K)+0.25,(R²=0.444,P<0.001).The restrictive effect of TN,TP,N:K content needs further experiments to explain.(4)Under normal water conditions,treatments with different concentrations of the 4 plant growth regulators had no significant difference in the soluble sugars of S.palustre.Under drought stress,spraying plant growth regulators can significantly increase the soluble sugar content of S.palustre,which is conducive to maintaining the normal required water in the body under drought stress and improving the ability to resist drought stress.(5)As the degree of drought stress increases,the productivity of S.palustre continues to decline.But compared with the control group,spraying a certain concentration of plant growth regulator can significantly increase the productivity of S.palustre.This study selected the optimal concentration of plant growth regulators under different water conditions,and the results of the study are of great significance for accelerating the recovery of sphagnum wetland and the industrialization of S.palustre.