| Petroleum pollution is serious in the oil production zone of northern Shaanxi Loess Hills area, and phytoremediation is an important technology for controlling petroleum pollution. Brassinolide(BL) can adjust the plant in adversity as a plant growth hormone.In this paper, three shrub species such as Robinia pseudoacacia, Amorpha fruticosa and Platycladus orientalis are used as the research material. The methods of pot experiment and laboratory analysis were adopted to research the dynamic changes of growth indexes, which is based on the 3 levels of petroleum contaminated soil as 10, 15, 20 g oil per kilogram of dry soil, then the seedlings are planted by dipping roots and spraying leaves of seedlings with different concentrations of brassinolide(0,0.1,0.3 and 0.5 mg?L-1).The growth status, osmotic regulation substances,antioxidant protection system and photosynthetic fluorescence index were analyzed.When the petroleum concentration is in the range of 10~20 g?kg-1, the main changes of growth and physiological characteristics of seedlings are as follows:(1)The growth of three seedlings improved with brassinolide treatment under petroleum pollution. The seedlings height and ground diameter growth rate is significantly higher than that of control,the height increased 7.02%~17.05% ground diameter increased 5.93%~11.14%, the ground dry weight increased 9.67%~113.51%,the length of the main root increased, the length and the number of level one and two root increased,lateral root, root dry weight increased 7.11%~134.56%..The brassinolide can alleviate petroleum effects stress on seedlings growth effectively,and the 0.3 mg?L-1 brassinolide concentration treatment has the best seedling growth response.(2)The content of osmotic regulation of the three seedlings were higher than the control in the whole sampling period, the proline content increased of 12.25%~105.04%, soluble sugar content increased by 21.71%~244.76%,soluble protein increased by 10.00% ~ 162.53%.The treatment of the 0.3 mg?L-1 brassinolide concentration is the most obvious.The brassinolide enhances the osmotic regulation effect in adversity, maintains the balance of the active oxygen in plant body.(3)Brassinolide can increased the antioxidant protection enzymes activity of SOD, APX,CAT, and GR significantly of seedlings, and the treatment of the 0.3 mg?L-1 brassinolide concentration is the best,the activity of SOD, APX,CAT, and GR increased 10.34%~ 203.92%,18.56%~183.59%,12.22%~125.42%,32.59%~255.14% respectively.The content of ASA, GSH added significantly,and the treatment of the 0.3 mg?L-1 brassinolide concentration is the best,the content most added 13.58%~254.12%,12.56%~259.62% respectively. BL effectively removes excessive reactive oxygen species in seedlings, maintains normal function of cell membrane. The improvement of antioxidant enzyme activity and antioxidant content enhance the effect of plant cell protection under soil petroleum pollution, and removal of excessive active oxygen in seedlings.(4)The application of brassinolide increased photosynthetic parameters.The 0.3 mg?L-1 concentration is the most effective. The leaf photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration increased 11.19%~ 43.06%, 19.93%~83.81%,25.84%~64.81%,6.42%~25.00% respectively, Fv/Fm,q P, φPSⅡ and ETR increased 4.77%~7.84%,1.31%~12.03%,4.93%~15.46%,6.85%~21.97% respectively.BL can open seedlings stomatal, increase photosynthetic substrates CO2,enhance the seedlings light energy conversion efficiency and improve enhance the carboxylation capacity of seedlings mesophyll cells,enhance photosynthesis of seedlings under petroleum pollution stress. |
PDF Full Text Request