水淹对枫杨幼苗光合生理特征的影响

Effects of flooding on the photosynthetic physiology characteristics of Pterocarya stenoptera seedlings

通过设置对照(CK)、连续性水淹(CF)和间歇性水淹(PF)3个水分处理,模拟三峡库区库岸带土壤水分变化,研究乡土树种枫杨当年实生幼苗的生理生态适应机制.结果表明:不同水分处理均显著影响枫杨幼苗的光合作用、生物量积累和生长.与CK相比,CF和PF组枫杨幼苗除胞间CO2浓度升高,净光合速率(Pn)、气孔导度(gs)均显著降低.其变化趋势是枫杨幼苗的Pn、gs在试验初期下降,然后逐渐恢复或趋于稳定.随着处理时间的延长,CF和PF组枫杨幼苗的总生物量、根生物量、茎生物量、叶生物量、株高和地径均呈现上升趋势.CF和PF组的总生物量、根生物量、叶生物量和株高,以及PF组的茎生物量均显著低于CK,而CF组的茎生物量与CK无显著差异,其地径还高于CK.枫杨幼苗具有耐受水湿而不耐水淹-干旱交替的生理生态特征.

Three water treatments （ control, CK; continuous flooding, CF; and periodic flooding, PF） were installed to simulate the soil moisture change of the riparian zone in the Three Gorges Reservoir （TGR） region of China to study the physiological and ecological adaptation mechanisms of the native plant species Pterocarya stenoptera seedlings to the soil moisture change. All the water treatments had significant effects on the photosynthesis, biomass accumulation, and growth of the P. stenoptera seedlings. As compared with those in CK, the seedling＇s net photosynthetic rate （ Pn ） and stomatal conductance （gs） in treatments CF and PF were significantly lower while the in- tercellular carbon dioxide concentration was significantly higher, and the Pn and g, in CF and PF declined initially followed by a gradual recovery or tended to be stable. With the extension of treat- ment time, the total biomass and root-, stem-, and leaf biomass, plant height, and basal diameter in CF and PF all presented an increasing trend. Throughout the experimental period, the total bio- mass, root- and leaf biomass, and plant height in CF and PF and the stem biomass in PF were sig- nificantly lower than those in CK, whereas the stem biomass in CF had no significant difference with that in CK, though the basal diameter in CF was significantly higher than that in CK. It was sugges- ted that the P. stenoptera seedlings had the physiological and ecological characteristics of tolerating flooding rather than flooding-drought alteration.