淹水胁迫对青杨雌雄幼苗生理特性和生长的影响

 为揭示青杨(Populus cathayana)雌雄幼苗对淹水胁迫的适应性, 在实验地内通过土培盆栽淹水方式从植株生理生态和生长发育方面探讨淹水胁迫对青杨扦插苗的影响。试验分为对照和淹水2个处理, 处理时间为40天。结果显示: (1)淹水胁迫导致青杨幼苗叶片中的丙二醛(MDA)含量和茎部淹水区的不定根数显著升高, 植株的净光合速率(P_n)、叶绿素含量、超氧化物歧化酶(SOD)活性、株高、基径、总叶面积、比叶面积(SLA)、根生物量、叶生物量、茎生物量、总生物量干重和根冠比(R/S)显著降低。(2)与雄株相比, 淹水胁迫显著增加了雌株幼苗的MDA含量, 降低了SOD活性、P_n、类胡萝卜素(Caro)含量、叶绿素a/b、SLA、根生物量和R/S, 并导致雄株在淹水胁迫下具有比雌株更高的气孔导度(G_s)、胞间CO₂浓度(C_i)、蒸腾速率(T_r)、不定根数和株高。可见, 淹水胁迫对青杨雌雄幼苗的形态生长和生理过程均有严重的抑制作用, 但表现出显著的性别间差异。雄株可以通过维持更高的光合作用能力和增加不定根数量来维持植株的生长, 从而表现出比雌株更强的抗逆性。

Effects of waterlogging stress on the growth and physiological characteristics of male and female Populus cathayana seedlings

Aims Although the influences of waterlogging disturbance on the physiology and growth characteristics of plants have been reported for many angiosperms, few studies were carried out in dioecious plants. Our objective was to explore the differences between the sexes of a dioecious species, Populus cathayana, in sex-related growth and physiological responses to waterlogging.
Methods One-year-old male and female P. cathayana seedlings were grown in plastic pots in Nanchong, Sichuan Province, China and were subjected to two water regimes: control (common soil water content) and waterlogging (water level 4 cm above soil surface) for 40 days of growth. We investigated sexual differences in malondialdehyde (MDA) content, photosynthetic pigments, gas exchange characteristics, antioxidant enzyme and morphological indices at the end of the experiment.
Important findings The waterlogging treatment significantly increased MDA content and number of stems with adventitious roots under water, as well as decreased net photosynthetic rate (P_n), chlorophyll content, super-oxide dismutase (SOD) activity, plant height, basal diameter, total leaf area, specific leaf area (SLA), root biomass, leaf biomass, stem biomass, total biomass and root/shoot ratio (R/S). Moreover, the waterlogging treatment significantly increased MDA content but decreased SOD activity, P_n, carotenoids (Caro) content, chlorophyll a/b ratio, SLA, root biomass and R/S in female plants, and males had higher stomatal conductance (G_s), intercellular CO₂ concentration (C_i), transpiration rate (T_r), more adventitious roots and greater plant height than females. The results indicated that morphological growth and physiological progress of the P. cathayana seedlings were seriously inhibited by the waterlogging treatment. Males may possess greater waterlogging resistance than females with higher photosynthetic capacity and number of adventitious roots maintaining plant growth under waterlogging stress.