| Eucalyptus is the main artificial forest tree species in Guangxi.It’s planting area occupied the national first place.During the production and management of the eucalyptus,young forest artificial cultivation is a heavy work.The application of chemical herbicide is equipped with many advantages,such as save time,save labor,invest less and high profit,etc.But it is inevitably that drift and splash droplets will expose to the seedlings and damage to the non-target species.In this study,effects of herbicides on the growth and physiological index of eucalyptus seedlings were studied by simulating the amount of splash and drift of herbicide in practice.It provides a scientific basis for eucalyptus forest to use herbicide scientifically and improve the technology of the chemical weed control.The main results are as follows:1.All concentrations of herbicide caoshu(0.046%～0.32%)are harmful to Eucalyptus urophylla X E.grandis seedlings,their phytotoxicity level and injury index increase with the addition of caoshu concentration.2.The herbicide caoshu has a significant inhibitory effect on the high growth and root growth of Eucalyptus urophylla × E.grandis seedlings.In detail,the growth of the root elongation and the addition of surface area and volume of root system are restrained.The number of root tip of Eucalyptus urophylla × E.grandis seedlings were sharply reduced after spraying herbicide caoshu.3.After herbicide caoshu treatment,biomass and water content of Eucalyptus urophylla× E.grandis seedlings were reduced.The biomass and water content of root,stem and leaf of Eucalyptus urophylla × E.grandis seedlings were decreased with the addition of the herbicide caoshu concentration of treatment.The water content of the leaves of Eucalyptus urophylla X E.g,randis seedlings were reduced that reached at the significant level(p<0.05).4.The herbicide caoshu reduced the chlorophyll content and inhibited the photosynthesis of Eucalyptus urophylla X E.grandis seedlings.The net photosynthetic rate and transpiration rate of seedings decreased significant with the increase of the concentration of herbicide caoshu,while the intercellular CO2 concentration was significantly increased,which indicated that the photosynthesis CO2 assimilation was obviously blocked.5.After herbicide caoshu treatment,the soluble sugar content of Eucalyptus urophylla× E.grandis seedling was significantly higher than that of control(p<0.05).The soluble sugar content of Eucalyptus urophylla X E.grandis seedling increased at first and decreased with the addition herbicide caoshu concentration subsequently.The soluble protein content of Eucalyptus urophylla X E.grandis seedling was also increased with the increase of the concentration of herbicide caoshu treatment.Among them,the soluble protein content of Eucalyptus urophylla X E.grandis seedling was significantly higher than that of the control after middle and high concentration of herbicide caoshu which are 300 times and 100 times of dilution treatment(p<0.05).6.The cell membrane permeability and MDA content of Eucalyptus urophylla X E.grandis seedlings increased with the increase of herbicide caoshu concentration.The permeability of the cell membrane of Eucalyptus urophylla X E.grandis seedlings after herbicide caoshu treatment was significantly higher than those in control group(p<0.05)7.Herbicide treatment had a significant effect on the protective enzyme activity of Eucalyptus urophylla X E.grandis seedlings,and the activity of the enzyme showed a tendency that increased significantly at first and decreased markedly subsequently.Under the treatment of low concentration herbicide caoshu,which was diluted 700 times,the Eucalyptus urophylla × E.grandis seedlings protective enzyme activities of POD,SOD and CAT were significantly higher then those in control(p<0.05). |
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