模拟酸雨对柚木幼苗生长、光合与水分利用的影响

模拟pH6.5(对照)、4.5和2.5三个酸雨梯度,研究其对1a生组培柚木(TectonagrandisL.f.)幼苗生长、光合与水分利用的影响。结果表明,尽管不同处理间的各项生理指标差异不明显,但模拟酸雨对柚木形态构件参数造成较严重的影响。pH4.5和pH2.5处理组柚木基径(D)和树高(H)增长明显下降,使得D2H下降更加显著;不同处理下柚木叶片净光合速率(Pn)和蒸腾速率(E)日变化趋于一致,气孔导度(gs)日变化与对应的叶片净光合速率日变化十分相似,同时,对照与两个处理的Pn与gs之间都表现正相关(p<0.01),且在pH4.5处理表现更为显著,但是对照和两个处理的E与gs的线性关系不显著;pH4.5和2.5处理的水分利用效率(WUE)日变化趋于一致;对照胞间CO2浓度与大气CO2浓度比(Ci/Ca)均值最低,表明对照柚木对CO2利用最有效。

Effects of Simulated Acid Rain on Water Use Efficiency the Growth, Photosynthesis and in Tectona grandis

One-year-old seedlings of teak(Tectona grandis L.f.,Verbenaceae) from tissue culture were potted for simulated acid rain experiments in Guangzhou.Acid solution was prepared with H2SO4 and HNO3 adjusting to pH2.5,pH4.5 and pH6.5 for control.Seedlings were applied with acid solution once with 3 days after potting for 4 weeks from 10 June to 20 October,2000,to study the effects of stimulated acid rain on the growth,photosynthesis and water use efficiency in teak.The results showed that the morphological parameters of the investigated seedlings were influenced significantly by acid application although no statistical difference in physiological parameters were found among treatments.The basal diameter(D) and plant height(H) of teak,particularly their combination(D2H) declined under pH4.5 and pH2.5.There were no difference in net photosynthetic rate(Pn),transpiration rate(E) and stomatal conductance(gs) between different treatments.For all treatments,Pn was positively correlated with gs,especially under pH4.5,but the relation of E with gs was relatively low.Diurnal changes in water use efficiency(WUE) of the plants treated with pH4.5 and pH2.5 solutions were quite similar with the exception of those treated with pH6.5.The average ratio of intracellular CO2 concentration and ambient CO2 concentration(Ci/Ca) was lowest in control(pH6.5),compared with other two acid treatments,implying that teak in the control was most effective in CO2 utilization.