不同土壤中杜鹃抗旱性和生长的比较研究

Comparative Study of Drought Resistance and Growth of Rhododendron in Different Soil

杜鹃为“木本花卉之王”和长沙市市花,在长沙市海绵设施中广泛应用。为了以低成本改良海绵设施中土壤,保证设施内杜鹃的抗旱性和观赏性,以原土、椰糠土(椰糠∶粗砂∶原土为2∶4∶4)、谷糠土(谷糠∶粗砂∶原土为2∶4∶4)、锯末细砂土(锯末:细砂:原土为2∶4∶4)和锯末粗砂土(锯末∶粗砂∶原土为2∶4∶4)为基质,以叶片含水量和生理指标为参数,研究了不同土壤中栽培杜鹃抗旱性及生长的变化。结果表明,原土中种植的杜鹃干旱30 d后死亡。椰糠土、谷糠土、锯末细砂土和锯末粗砂土中种植的杜鹃干旱30 d后生长受到抑制,表现为最大光合速率、ETR(表观光合电子传递速率)、qP(光化学淬灭系数)、Fv/Fm(最大光能转换)和呼吸速率值的下降,但是不同土壤各指标下降程度不同。椰糠土、谷糠土、锯末细砂土和锯末粗砂土中种植的杜鹃干旱30 d复水一周后,植物恢复生长,表明椰糠土、谷糠土、锯末细砂土和锯末粗砂土壤的保水能力增强,能增强杜鹃的抗旱能力。各指标的相关性分析结果表明,叶片含水量、最大光合速率、光补偿点、呼吸速率与其他指标的相关性明显。主成分分析表明,qP、ETR、叶片含水量、叶绿素含量、Fv/Fm、光补偿点6个指标能反映杜鹃的抗旱能力。成本分析表明锯末粗砂土成本最低,因而在海绵设施改良土壤中,锯末粗砂配比土壤,不仅能增加杜鹃的抗旱性,而且成本较低,值得推广。

Rhododendron,the king of woody flowers and the city flower of Changsha,is widely used in sponge facilities in Changsha.In order to increase the drought resistance and ornamental of Rhododendron in sponge facilities at a lower cost,the Rhododendron were planted in the soil of original soil,coconut sugar soil(ratio of coconut bran:coarse sand:original soil was 2:4:4),rice bran soil(ratio of corn bran:coarse sand:original soil was 2:4:4),sawdust fine sand(ratio of sawdust:fine sand:original soil was 2:4:4),sawdust coarse sand soil(ratio of sawdust:coarse sand:original soil was 2:4:4).The growth and drought insistence were determined by physiological indexes and water content in leaf.The results showed that the plants in the original soil died after drought for 30 d,which embodied the decreasing of maximum photosynthetic rate,ETR,qP,Fv/Fm and respiratory rate,but the decreasing of different indexes were different.After treated with drought for 30 d and re-watered for one week,Rhododendron in coconut soil,rice bran soil,sawdust fine sand soil and sawdust coarse sand soil recovered.The changes indicated that the water holding capacities of coconut soil,rice bran soil,sawdust fine sand soil and sawdust coarse sand soil were enhanced,which could enhance the drought resistance ability of Rhododendron.The correlation analysis of indexes showed that leaf water content,maximum photosynthetic rate,light compensation point and respiration rate were significantly correlated with other indexes.Principal component analysis showed that qP,ETR,leaf water content,chlorophyll content,Fv/Fm and light compensation point could better reflect the drought resistance of Rhododendron.Cost analysis showed that the cost of sawdust coarse sand(treatmentⅢ)was the lowest.The proportion of sawdust and coarse sand for soil improvement in sponge facilities can not only increase the drought resistance of Rhododendron,but also have low cost,which is worthy of promotion.