Effects Of Exogenous Regulators On Root Growth Characteristics And Enzyme Activities Of Cotton

In this study,the main cotton varieties in Xinjiang,Zhongmian"619"（Z619）,Xinluzao"27"（Z27）and Xinluzao"39"（Z39）,were taken as the research objects,and the bag experiment and pot experiment of cotton seed germination were carried out in the artificial climate room of Tarim University from 2019 to 2020.Three exogenous regulators were selected in the experiment,which were gibberellin（GA₃）,salicylic acid（SA）and paclobutrazol(PP₃₃₃),and each exogenous regulator had three concentration levels.The effects of exogenous regulators on cotton growth at germination and seedling stages in Xinjiang were revealed from the aspects of root morphology,biomass accumulation and root enzyme activity,and the responses of root morphological parameters,aboveground and underground biomass accumulation and root enzyme activity to different concentrations of exogenous regulators were analyzed.The main conclusions are as follows:（1）the effects of different exogenous regulators on cotton roots during germination were studied by germination bag experiment.the results showed that 0.2 mg/L GA₃ could promote the development of Z619roots,and the main root length and total root length increased by 7.4%and 10.2%respectively compared with CK.0.01 mmol/L SA can effectively promote the root growth and development of cotton varieties at germination stage,and the biomass and root-shoot ratio are significantly increased;0.1 mg/L PP₃₃₃ can promote the root development of Z619 and Z27 cotton,the main root length is increased by 16.0%and 14.3%compared with CK,and the underground biomass and root-shoot ratio are also increased.0.25 mg/L PP₃₃₃can obviously improve the morphological indexes of Z39 root system and promote the overall development of root system.（2）In the seedling stage of cotton,pot experiments were conducted to study the effects of different exogenous regulators on cotton growth.The results showed that 0.05 mg/L GA₃ significantly increased the total root length of Z619 and Z27,while decreased the average root diameter,but had no obvious effect on the underground dry matter and root-shoot ratio of Z619.0.01 mmol/L SA significantly increased the total root length,total root surface area and root volume of Z619 and Z39 at seedling stage,but had no significant effect on plant height,leaf area,biomass and root-shoot ratio.0.05 mmol/L SA can promote the total root length,total root surface area and root volume of Z27,but the difference is not significant.0.1 mg/L PP₃₃₃can obviously increase the total root length and total root surface area of Z619 and decrease the average root diameter.Treatment with PP₃₃₃ inhibited the root development of Z27 at seedling stage,and 0.25 mg/L and0.5 mg/L PP₃₃₃ also inhibited the root development of Z39 at seedling stage.（3）The study on the effect of different exogenous regulators on the enzyme activity of cotton roots showed that 0.05 mg/L GA₃ had no obvious effect on soluble protein of roots of Z619 and Z27 at seedling stage,but decreased the activity of superoxide dismutase（SOD）and increased the activity of peroxidase（POD）.SA treatment with different concentrations can increase SOD activity of Z619 and Z27 roots.0.01mmol/L SA had no obvious effect on soluble protein content and POD activity of Z619 and Z39 roots.0.05mmol/L SA had no obvious effect on soluble protein content and POD activity of Z27.0.1 mg/L PP₃₃₃ can increase SOD and POD activities of Z619 root system,but has no obvious effect on soluble protein content,and can also increase SOD activity of Z27 cotton root system.