盐胁迫下3个楸树无性系光合特征研究

以3个楸树无性系为材料进行盐胁迫试验,分析了叶片叶绿素含量、净光合速率(P_n)、气孔导度(G_s)、胞间CO₂浓度(C_i)等指标的变化规律。结果表明:随盐浓度增加,所有无性系的叶绿素a、叶绿素b及总叶绿素含量呈下降趋势;方差分析表明:处理间及无性系间差异显著(P＜0.05)。叶绿素a/叶绿素b值呈上升趋势,YQ₁无性系各盐处理与CK差异不显著,02-2-5和07-1无性系各盐处理与CK存在一定差异。从光合日变化看,3个无性系的P_n随盐浓度的升高明显降低,降幅为07-1〉YQ₁〉02-2-5,净光合速率最大值(P_max)都出现在8:00时,无性系间差异显著,且02-2-5〉YQ₁〉07-1。回归分析和通径分析表明:02-2-5和YQ₁无性系主要受胞间CO₂浓度(C_i)、叶温(T_l)、光合有效辐射(PAR)的影响,07-1无性系主要受G_s和C_i的影响。初步认为3个无性系的耐盐能力为02-2-5〉YQ₁〉07-1。

Studies on Photosynthetic Characteristics of Three Clones of Catalpa bungei under Various Salt Stress

The leaf chlorophyll contents, the daily dynamic of net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i) and major affecting factors were determined of three clones of Catalpa bungei under salt stress.The results showed that Chla, Chlb and Chlt contents decreased under salt stress and significant differences were found of Chla, Chlb and Chlt among 3 clones of C. bungei.The ratios of Chla/Chlb increased with the increasing of salt concentration, and significant differences were found in different treatments of 02-2-5 and 07-1.The maximum of P_n (P_max) appeared at 8:00 in all treatments of 3 clones, with the sequence of 02-2-5>YQ1>07-1,and significant differences were found in 3 clones.P_n was also decreased with the increasing of salt concentration, and the sequence of decrement was 07-1>YQ₁>02-2-5.Stepwise multiple-regression and path coefficient analysis indicated that the major affecting factor of P_n were C_i, leaf temperature (T_l) and photosynthetic active radiation (PAR) in clones of 02-2-5 and YQ₁, but G_s and C_i in 07-1.Based on the variations of leaf chlorophyll contents and Pn among 3 clones under salt stress, 02-2-5 had the highest salt tolerance, followed by YQ₁, and 07-1.