四环素对烤烟生长发育及光合作用的影响研究

为明确典型抗生素残留对烟草的生态毒理效应,采用盆栽试验系统研究了不同剂量四环素添加对烤烟生长发育及光合作用的影响。结果表明:在烟草生长发育过程中,低量四环素添加(5 mg·kg~(-1))能促进烟草株高增加,中高量的四环素添加(50 mg·kg~(-1)及500 mg·kg~(-1))对株高具有明显抑制作用,但促进了茎围和叶片数的增加。此外,低量四环素对烟草根长及根体积有一定促进作用,高量则产生抑制作用,且抑制作用随生育进程而逐渐减弱,至生育后期已无明显影响。四环素添加各处理的烟草根冠比总体上均低于对照(团棵期除外),且根冠比随四环素添加量的增加而降低。四环素对烟草净光合速率、气孔导度和蒸腾速率的影响,随生育进程呈现前期抑制后期促进的趋势,对胞间CO_2浓度的影响则无明显规律性。该研究显示,四环素可能通过影响烟草光合作用而对烟草生长发育产生重要作用,同时烟草通过调控根系发育及根冠比来适应四环素的影响。因此,中高量的四环素添加对烟草生长发育及光合作用具有一定的生态毒性效应,但毒性效应随着烟草生育进程而减弱。

Effect of tetracycline on the growth and photosynthesis of flue-cured tobacco

In order to evaluate the eco-toxicological effects of typical antibiotics residue on tobacco, the effects of tetracycline addition on tobacco growth and photosynthesis were studied via pot experiments. The results showed that during the whole growth period of tobacco, the low amount of tetracycline addition(5 mg·kg^-1) could increase the tobacco height. The middle and high amount of tetracycline addition(50 mg·kg^-1 and 500 mg·kg^-1) had an obvious inhibitory effect on tobacco height, but they promoted the increase of stem circumference and leaf number of tobacco. Furthermore, the low amount of tetracycline addition could promote root length and root volume of tobacco, while the high amount of tetracycline addition inhibited tobacco root growth, and the suppression gradually decreased with the growth stages, with no significant difference on the late growth stage. The root to shoot ratio of tobacco in the tetracycline addition treatments were lower than that in CK during the whole growth period except for the resetting stage, and it decreased with the increase of the amount of tetracycline addition. Tetracycline addition first inhibited then enhanced the photosynthetic rate, stomatal conductance and transpination rate during the tobacco growth period, but its effect on intercellular CO₂ concentration had no obvious regularity. These results indicated that tetracycline might have a potential impact on tobacco growth through influencing photosynthesis. Meanwhile, tobacco could adapt the effect of tetracycline by regulating root development and the root to shoot ratio. Therefore, the effects of middle and high amount of tetracycline addition on tobacco growth and photosynthesis showed a certain eco-toxicity, which decreased with the growth stages of tobacco. The specific mechanism of tetracycline on tobacco growth and its risk assessment in tobacco field need to be further studied.