地表臭氧浓度升高与干旱交互作用对杨树非结构性碳水化合物积累和叶根分配的短期影响

人类活动加剧和全球变化导致植物在生长季同时受到高浓度地表臭氧(O₃)和干旱的双重胁迫。为了探究两者对植物非结构性碳水化合物(TNC)积累和分配的影响, 该实验采用开顶式气室研究了2种O₃浓度(CF, 过滤空气; NF40, NF (未过滤空气) + 40 nmol·mol ^-1 O₃)和2个水分处理(对照, 充分灌溉; 干旱, 非充分灌溉)及其交互作用对杨树基因型‘546’ (Populus deltoides cv. ‘55/56’ × P. deltoides cv. ‘Imperial’)叶片和细根中TNC及其组分(葡萄糖、果糖、蔗糖、多糖、总可溶性糖和淀粉)含量的影响。结果表明: O₃浓度升高显著降低杨树叶片中淀粉和TNC的含量, 增加葡萄糖、果糖和总可溶性糖含量, 但对细根中淀粉和总可溶性糖含量的影响不显著。干旱胁迫显著增加细根中果糖和多糖含量, 降低蔗糖含量, 但对叶片中淀粉和总可溶性糖含量的影响不显著。充分灌溉下O₃浓度升高显著增加了杨树叶片多糖和总可溶性糖含量, 而干旱下O₃浓度升高显著增加了TNC含量的根叶比。该研究结果发现O₃主要影响叶片中TNC及各组分的含量, 而干旱主要影响细根中TNC及各组分的含量。从杨树叶片TNC的响应来看, 适度的水分限制有助于减缓O₃的负面伤害。

Short-term effects of combined elevated ozone and limited irrigation on accumulation and allocation of non-structural carbohydrates in leaves and roots of poplar sapling

AimsIntensified human activities has resulted in more extreme droughts and high ground-level ozone (O₃) concentration during plant growing seasons. To clarify the combined effects of elevated O₃ (E-O₃) and drought on plants, we investigated the effects of elevated O₃, drought and their interaction on the accumulation and allocation of non-structural carbohydrates (TNC) in leaves and fine roots of poplar.MethodsThe O₃-sensitive poplar ‘546’ (Populus deltoides cv. ‘55/56’ × P. deltoides cv. ‘Imperial’) saplings were exposed to two O₃ treatments (charcoal-filtered air (CF) and non-filtered ambient air (NF) + 40 nmol·mol^-1 O₃ (E-O₃)), and two watering treatments (control, well-watered and drought, reduced watering) using open-top chambers (OTC_S). The content of TNC and its components (glucose, fructose, sucrose, polysaccharides, total soluble sugars and starch) in leaves and fine roots were measured.Important findings E-O₃ significantly decreased the content of starch and TNC, but increased the content of fructose, glucose and total soluble sugar in leaves. However, E-O₃ did not have significant effects on starch and soluble sugars in fine roots. In addition, drought significantly increased the content of fructose and polysaccharide, but decreased the content of sucrose in fine roots, although drought had no significant impacts on the content of starch and soluble sugars in leaves. There was significant interaction of O₃ and drought on the content of polysaccharides and total soluble sugar in leaves, as indicated by the significant increase by E-O₃ under well-watered irrigation, but no effects under drought. E-O₃ significantly increased the ratio of root to leaf in TNC content, but not under well water condition. In conclusion, E-O₃ affected the content of TNC and its components in leaves, while drought affected them in fine roots. From the response of TNC, moderate drought mitigates the negative effects of O₃ pollution on plants.