不同水分生境下铅胁迫对芦苇地下芽及其输出子株能力的影响

为明确铅胁迫对不同水分生境条件下芦苇的不同克隆繁殖构件数量和繁殖能力的影响,从芽库和子株角度,采用盆栽实验模拟芦苇的水层和干旱生境,设置五个梯度的铅胁迫浓度处理(0、500、1500、3000和4500mg·kg~(-1))进行了研究.结果表明:分蘖节芽数在水层生境中,处理前期随着铅胁迫浓度的增加而显著减少,而在处理中期和后期却均显著增加,在干旱生境中处理前、中、后期铅胁迫对分蘖节芽数无显著影响.根茎节芽、根茎顶芽和总芽数无论是在水层生境还是在干旱生境,均随着铅胁迫浓度的增加而显著减少.分蘖节子株数在水层生境中,处理前期随着铅胁迫浓度的增加而显著减少,而在处理中期和后期却无显著变化,在干旱生境中随着铅胁迫浓度的增加而显著减少.根茎节子株不存在,根茎顶子株无论是在水层生境还是在干旱生境,均随着铅胁迫浓度的增加而显著减少.总子株数在水层生境中处理中期显著减少,处理后期无显著变化,在干旱生境中处理中期和后期均显著减少,并且总芽数+总子株数在胁迫前期和中期随铅胁迫浓度的增加显著减少.说明不同类型芽具有不同的抵御铅胁迫的策略,分蘖节芽采取了耐性策略而不受影响甚至增加,其他类型的芽采取了逃避策略数量减少;水生生境的芦苇具有逐步适应铅胁迫的能力,并出现了补偿生长效应,而干旱生境进一步加剧了铅胁迫的作用,铅胁迫和干旱具有协同效应.

Effects of lead contamination on underground bud and output of aboveground shoots of Phragmites australis (common reed) under different water regimes

In order to determine the effects of lead (Pb) stress on the propagation ability of common reed under different water levels, pot culture experiments were conducted to investigate the effects of Pb concentration (0, 500, 1500, 3000, 4500 mg kg^-1) in environments with contrasted water levels on the clonal reproductive ability of this species.The 3 stages included the early stage(sampling after 30 days since onset of water stress),the middle stage (sampling after 60 days)and late stage(sampling after 90 days).The results showed that in a wet environment, the number of axillary shoot buds at an early stage significantly decreased with the increase of Pb concentrations, while the response was the opposite at the middle and late stages.The number of axillary shoot buds at all developmental stages was not significantly affected by Pb in the dry environment. The number of axillary, apical rhizome shoot buds, and total buds in both wet and dry environment, decreased significantly with the increase of Pb concentrations. The number of daughter axillary shoots in the wet environment decreased significantly with the increase in Pb concentrations at the early stage,but there were no significant changes during later stages in the dry environment. Daughter axillary rhizome shoots were not observed neither in the wet or dry environment at all Pb levels. The sum of shoots in the wet environment during the middle stage was significantly reduced, with no significant change observed at the later stage; in the dry environment they were significantly reduced at the middle stage and the late stage. The sum of buds and sum of shoots were significantly reduced during the early and middle stage with increased Pb concentrations.The results demonstrated that different types of buds had different tolerance to Pb stress. Axillary shoot buds were not affected or even positively responded to increased Pb levels, while other bud and shoot types were reduced. Common reed in a wet environment has the ability to adapt to the Pb stress gradually having a compensatory growth effect, while a dry environment the effect of Pb is greater, and it seems that there is a synergistic effect between Pb and drought.