暖季型与冷季型草坪草差异响应干旱及旱后复水的生理生态机制

摘要

暖季型草坪草与冷季型草坪草抗旱及旱后复水恢复能力不同，解析这种差异的生理生态机制有助于抗旱草坪草育种。本试验以暖季型草坪草海滨雀稗和冷季型草坪草草地早熟禾为试验材料，探讨了干旱和旱后复水处理对两种草坪草叶片相对含水量（RWC）、净光合速率（P n ）、气孔导度（Gs ）、蒸腾速率（T r ）、比叶面积（SLA）、渗透调节能力（OA）、水分利用效率（WUE）以及根系总长度等生理生态指标的影响。结果表明，海滨雀稗比草地早熟禾具有较强的抗旱能力，表现为具有较高的 RWC、P n 、T r 、Gs 和 WUE，最高时分别比草地早熟禾高出11％，33％，52％，119％，27％；另外，干旱条件下草地早熟禾0～20 cm 土层中的根系总长度出现显著下降也是其抗旱性低于海滨雀稗的一个重要因素；复水后，较高的 RWC （9％）、T r （43％）、Gs （154％）、WUE （34％）和较低的 SLA （8％）是海滨雀稗旱后恢复能力优于草地早熟禾的原因。%Warm-season grasses had superior drought tolerance and post-drought recovery,compared to cool-season turfgrasses.In this study,seashore paspalum (Paspalum vaginatum cv.‘2000’)and Kentucky blue-grass (Poa pratensis cv.‘Excursion II ’)were chosen as research material.Leaf relative water content (RWC),water use efficiency (WUE),net photosynthetic rate (P n ),stomatal conductance (G s ),transpiration rate (T r ),specific leaf area (SLA),osmotic adjustment (OA)and root length were measured to clarify the mechanisms of their differential drought tolerance.Seashore paspalum had superior drought tolerance as shown by higher RWC (11%),P n (33%),T r (52%),G s (119%)and WUE (27%).Total root length in the 0-20 cm soil layer under Kentucky bluegrass was reduced significantly more after 20 d drought stress than under sea-shore paspalum,suggesting the former was less drought-tolerant.During post-drought recovery,seashore pas-palum had higher RWC (9%),T r (43%),G s (154%)and WUE (34%),as well as lower SLA (8%)than Ken-tucky bluegrass.Further,total root length in the 0-20 cm soil layer showed the same changes as that during drought stress.The results indicated that lower water loss,higher water use efficiency and the fact that root growth in 0-20 cm soil layer was less reduced under drought,were the main reasons for the superior drought tolerance and post-drought recovery ability of seashore paspalum,compared to Kentucky bluegrass.