铅胁迫下茅苍术生理指标、光合参数及生物量的变化

Changes of physiological indexes,photosynthetic parameters and biomass of Atractylodes lancea(Thunb.)DC.under lead stress

【目的】探究不同铅浓度下茅苍术的耐性差异,为江苏道地产区茅苍术的规范化种植及安全生产提供科学依据。【方法】采取随机区组设计盆栽模拟试验,以蒸馏水为对照(0 mg/kg,CK),采用乙酸铅[(CH3COO)2Pb]配制5个不同的Pb2+浓度(100、300、600、900和1200 mg/kg)处理,分别在胁迫0、7、14、21、28和35 d时随机选取生长较好的功能叶进行标记并测定其叶绿素含量和光合参数;在胁迫0、8、15、22、29和36 d时随机选取未标记且生长较好的功能叶进行生理指标检测;待地上部分枯萎,挖取根茎测其生物量。【结果】不同浓度的铅胁迫下,随胁迫时间的延长,茅苍术的叶绿素含量及净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)均呈先升高后降低的变化趋势,而胞间二氧化碳浓度(Ci)逐渐升高;在整个胁迫过程中,CK及100和300 mg/kg处理的抗氧化酶活性均呈逐渐上升趋势,600～1200 mg/kg处理的抗氧化酶活性则呈先升高后降低。叶片丙二醛(MDA)、脯氨酸(Pro)和可溶性糖含量及质膜透性随胁迫时间的延长整体上呈上升趋势,至胁迫后36 d均表现为1200 mg/kg>900 mg/kg>600 mg/kg>300 mg/kg>100 mg/kg>CK;随铅胁迫浓度的增大,茅苍术的根茎生物量逐渐降低。【结论】当Pb2+浓度低于300 mg/kg时,茅苍术可通过提高抗氧化酶活性及增加MDA和渗透调节物质含量以缓解胁迫抑制;当Pb2+浓度过高时,则导致植株正常的代谢机制失调,严重抑制植株生长。

【Objective】In order to provide a scientific theoretical basis for the standardized planting and safe production of Atractylodes lancea(Thunb.)DC. in Jiangsu production area,the experiments about exploring the tolerance differences of A. lancea(Thunb.)DC. under different lead concentrations were designed.【Method】The randomized blocks were used to design the pot simulation test. Distilled water was used as control(0 mg/kg,CK). lead acetate[(CH3COO)2Pb] was used to prepare five treatments with different Pb2^+ concentrations,being 100,300,600,900 and 1200 mg/kg,respectively. After the stresses of 0,7,14,21,28 and 35 d,functional leaves with good growth were randomly selected to be marked. And then chlorophyll contents and photosynthetic parameters of marked functional leaves were determined. After the stresses of 0,8,15,22,29 and 36 d,the unmarked functional leaves with good growth were randomly selected to determine their physiological indexes. When the aerial parts withered,the rhizomes were excavated to determine their biomass.【Result】Under different lead stress concentrations,the chlorophyll content and net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of A. lancea(Thunb.)DC. showed variation trend of increasing first and then decreasing with the prolongation of stress time. And the intercellular carbon dioxide concentration(Ci)increased gradually. During the whole process of stress,the activities of antioxidant enzymes in treatment groups of CK,100 and 300 mg/kg showed a gradually increasing trend. The activities of antioxidant enzymes in treatment groups of 600-1200 mg/kg increased first and then decreased. The contents of malondialdehyde(MDA),proline(Pro),soluble sugar and plasma membrane permeability in leaves on the whole showed an increasing trend with the prolongation of stress time. After stress of 36 d,the contents of MDA,Pro,soluble sugar and plasma membrane permeability showed the relations of 1200 mg/kg >900 mg/kg >600 mg/kg >300 mg/kg >100 mg/kg >CK. With the increase of lead stress concentration,the biomass in rhizomes of A. lancea(Thunb.)DC. decreased gradually.【Conclusion】When the Pb2+concentration is lower than 300 mg/kg, A. lancea(Thunb.)DC. can be used to alleviate stress inhibition by improving the activity of antioxidant enzymes and increasing the content of MDA and osmotic regulators. But if Pb2+ concentration is too high,the normal metabolic mechanism of plant would be disordered and the growth of plant would be seriously inhibited.