【摘要】 以1a生楸树根插苗为试验材料,设置95%—100%FC、85%—90%FC、70%—75%FC、50%—55%FC等不同梯度的土壤含水量,对生长旺季的光合特征及生长量进行测量,研究苗期楸树对不同土壤水分含量的生长及光合特征响应。结果显示:高土壤含水量(≧85%FC)和低土壤含水量(≦75%)地径和苗高生长量差异显著(P<0.05),随着土壤含水量逐渐下降,地径和苗高生长量、根重、茎重及根干比均呈下降趋势。光合特征比较发现,上午净光合速率显著高于下午,净光合速率的日变化主要直接受制于气孔因素; 85%—90%FC处理叶片的净光合日总量最大, 50%—55%FC处理叶片的净光合日总量最小。在所有光强梯度下,高土壤水分含量处理(≧85%FC)的叶片净光合速率均明显较高,尤其是85%—90%FC处理,光利用能力和光合潜力都具有较大优势。从生长和光合特征综合分析结果可以看出,四种处理中85%—90%FC处理最有优势和潜力,是楸树苗期生长最为适宜的土壤含水量。更多还原

【Abstract】 In order to compare the differences of growth and photosynthetic characteristics of the Catalpa bungei seedlings at different soil water content, 1-year-old Catalpa bungei seedlings by root cutting were used as the experimental materials. Growth and photosynthetic characteristics were measured during fast-growing period in different soil water content. The results showed that there were significant differences(P<0.05) in height and base diameter increment among seedlings living in high soil water content(≧85% FC) and those living in low soil water content(≦75% FC). With the decrease of soil water content, height and base diameter increment, root weight, stem weight and root/stem were showing a downward trend gradually. The net photosynthetic rate measured in the morning was significantly higher than that measured in the afternoon, and the diurnal changes of net photosynthetic rate was mainly directly affected by stomatal factors. The day total net photosynthetic rate of 85%-90% FC treatment was the largest, and the day total net photosynthetic rate of 50%-55% FC treatment was the smallest. The net photosynthetic rate of leaf from high soil water content(≧85% FC) was significantly higher than that from low soil water content in all light intensity gradient, especially the 85%-90% FC treatment had a greater advantage in light utilization capacity and photosynthetic potential. Comprehensive analysis of growth and photosynthetic characteristics indicated that85%-90% FC treatment had the most advantages and potential in four treatments, which was the most appropriate soil water content in the seedling growth.更多还原