【摘要】 为探讨刺槐对不同喀斯特环境的适应能力及其在生态系统构建的配置方式,通过室内水培实验,人工模拟干旱、高重碳酸盐、低营养、缺磷4种喀斯特土壤生境胁迫,研究刺槐幼苗的光合特性、碳酸酐酶活力、δ¹³C值和干物质分配对不同喀斯特生境胁迫的响应及适应策略。结果表明:在干旱环境下,刺槐幼苗短期内（10天）最为敏感且受抑制最强,虽增加根冠比和水分利用效率,长期内（20天）能够维持生存;在高重碳酸盐环境下,因气孔导度降低,其通过骤增碳酸酐酶活力来增加溶液中HCO₃^-利用能力,以此提高茎叶干物质分配,长期保持较好生长力;在低营养环境下,短期内（10天）限制刺槐生长的主要因素为气孔限制,长期内（20天）通过上调碳酸酐酶活力增加对HCO₃^-的利用能力,提高根部干物质分配,但其生长仍受溶液无机元素的浓度限制;在缺磷环境下,刺槐通过上调碳酸酐酶活力来增加HCO₃^-利用能力,提高根部干物质分配,维持较高的生长能力。刺槐幼苗在不同喀斯特环境下表现出不同的适应机制,刺槐对4种模拟的喀斯特土壤环境胁迫适应性综合评价为:重碳酸盐>缺磷>低营养>干旱。更多还原

【Abstract】 To explore the adaptability of Robinia pseudoacacia to different karst environments and its configuration in ecosystem construction,four kinds of karst soil habitat stresses,including drought,high-carbonate,low-nutrient,and phosphorus-deficiency,were artificially simulated under indoor hydroponic experiment. We measured the photosynthetic characteristics,carbonic anhydrase activity,δ¹³C value and dry matter allocation of seedlings under different karst habitat stresses. The results showed that under drought environment,the seedlings of R. pseudoacacia were the most sensitive and inhibited in the short term（ 10 days）. Although the root-shoot ratio and water use efficiency were increased,the seedlings could survive in a longer term（ 20 days）.Under the high bicarbonate environment,R. pseudoacacia seedlings increased the utilization of HCO₃^- by increasing the activity of carbonic anhydrase due to the decrease of stomatal conductance,thereby improving dry matter allocation to stems and leaves and maintaining normal growth for a longer term. Under low nutrient environment,stomatal factor was the main limitation for the growth of R. pseudoacacia in a short term（ 10 days）. R. pseudoacacia increased the utilization of HCO₃^- in the solution by increasing the activity of carbonic anhydrase in the longer term（ 20 days）,and increased dry matter allocation to roots. However,the growth was still limited by the concentration of inorganic elements in the solution. Under phosphorus-deficient environment,the R. pseudoacacia seedlings increased the utilization of HCO₃^- in the solution by up-regulating the activity of carbonic anhydrase,increased dry matter allocation to roots,and maintained the high growth capacity. The adaptation strateiges of R. pseudoacacia seedlings differed under different karst environments. The results of comprehensive evaluation showed that the adaptation of R.pseudoacacia to four simulated karst soil stresses was in the order of high carbonate,phosphorus deficiency,low nutrition,and drought.更多还原