Study On Exogenous Brassinolide On The Regulation Of Xylem Development Of Quercus Mongolica

Brassinolide（BR）is a sterol phytohormone,which plays an important role in regulating embryonic development,vascular system differentiation,cell division,and stress resistance of plants.In order to investigate the effect and regulation of different concentrations of brassinolide on the xylem development of Quercus mongolica seedlings under spraying and irrigation methods,firstly,two months of seedlings of Quercus mongolica seedlings were used as research objects,and different concentrations of BR spray（0,0.01,0.1,1,10 mg / m L）,irrigation（0,0.05,0.5,5mg / m L）treatment of Mongolian oak seedlings,after BR treatment for 1 month to determine the height,ground diameter,biomass,root system of Mongolian oak seedlings Indicators and principal component analysis to obtain the optimal concentration and principal component evaluation model for two different treatment methods,followed by external application of BR and brassinolide biosynthesis inhibitor（BRZ）treatment by spraying and irrigation After 3 months of seedlings of Quercus mongolica,the main component indexes,cell wall components and cell structure of xylem were observed,and the mechanism of regulation of exogenous BR on the xylem development of Quercus mongolica was obtained.The research results are as follows:1)Brassinolide applied externally can effectively promote the development of Quercus mongolica.The optimum BR concentration for spray treatment was 0.1mg/m L.At 0.1 mg/m L,it could effectively promote the plant height growth of Quercus mongolica seedlings,up to 15.16 cm,and the ground diameter increased by up to 2.66 mm.The effects of root growth indexes such as root volume and root volume were not obvious.The optimum concentration of BR under irrigating treatment was 0.5 mg/m L.At 0.5 mg/m L,it could effectively promote the root growth of Quercus mongolica seedlings.The root thickness increased significantly to 6.52 mm,the root length increased to 15.69 cm,and the root volume increased significantly to 6.17.But the number of roots,ground diameter,seedling height and other indicators did not change significantly.The spraying treatment of BR effectively promoted the growth and development of Quercus mongolica,and the irrigation treatment effectively promoted the growth and development of roots.It is speculated that BR could not be transported over long distances,and the effect of promoting the effect was better.Effects of BR spray treatment on xylem development of Quercus mongolica2)Based on the comprehensive principal component evaluation value of BR spraying treatment,an evaluation model for the influence of BR spraying treatment on the xylem development of Quercus mongolica was established: Y=0.15X₁₀+0.05X₁₃+1.49X₂-5.45(Note:X₂: ground diameter,X₁₀: Thick root,X₁₃: number of roots).This model effectively evaluates the effect of exogenous spraying of BR on the growth and development of Quercus mongolica.Based on the comprehensive principal component evaluation value of BR irrigation treatment,an evaluation model of BR irrigation treatment affecting the xylem development of Quercus mongolica was established: Y=0.40X₁+0.28X₉-3.61（Note: X₁: seedling height,X₉: root volume）.This model effectively evaluates the effect of exogenous BR on Quercus mongolica growth and development.3)Mechanism of BR treatment on xylem development of Quercus mongolica.Compared with the control of BR spraying,the ground diameter increased by 0.22 mm,the stem biomass increased by 0.39 g,the number of primary xylem cell layers increased by 7,the diameter of xylem cells increased by 30%,and the diameter of phloem cells had no significant difference;lignin content;Significant increase in 146 mg.Compared with the control,the BRZ spraying treatment: the ground diameter is reduced by 0.35 mm,the stem biomass is reduced by 0.37 g,and the primary xylem cell layer and diameter have not changed significantly;the content of lignin and xylan is slightly reduced,and the content of cellulose is slightly Rise.BR mainly promoted the development of xylem in the stems of Quercus mongolica through the increase of the number of new xylem cells and the increase of lignin during spraying.The effect of BRZ was opposite.4)Mechanism of BR treatment on root xylem development of Quercus mongolica.Compared with the control of BR irrigation,the root thickness increased significantly by 1.98 mm,the seedling height increased slightly,the root volume increased significantly by 3.98,the root biomass increased significantly by 1.18 g,the lignin content decreased by 39 mg,the cellulose increased slightly,and the half fiber There was no change in the vegetarian content.Compared with the control of BRZ irrigation,the root thickness increased by 1.22 mm,the seedling height decreased slightly,the root volume increased by 2.1,the root biomass increased by 0.71 g,the content of lignin and hemicellulose remained almost unchanged,and the cellulose content decreased slightly.BR mainly promotes the development of xylem in the roots of Quercus mongolica by increasing the number of xylem cells and reducing lignin during irrigation.The effect of BRZ is the same,but the promotion effect is lower than BR.