土壤盐胁迫对海州常山形态与气体交换特性的影响

海州常山Clerodendrum trichotomum观赏性好，适应性强。采用盆栽试验方法，研究了0～8g·kg^-1范围内不同质量分数梯度盐（NaCl）胁迫对1年生海州常山的形态、叶绿素质量分数、气体交换特征及水分利用效率的影响。结果表明，随着盐分胁迫的增大和胁迫时间的延长，新梢和功能叶片逐渐失绿甚至焦边枯黄；叶绿素a、叶绿素b、叶绿素a／b、气孔导度、蒸腾速率、水分利用率和净光舍速率等逐渐下降；细胞间隙CO2先下降后有所回升，气孔限制值的变化与细胞间CO2摩尔分数相反。研究证实，短期盐分胁迫导致海州常山净光合速率下降的原因以气孔限制因素为主，中长期胁迫则以非气孔限制因素为主：试验条件下短期内海州常山的耐盐性不超过6g·kg^-1。图5参14

Soil NaCl stress and photosynthetic characteristics with Clerodendrum trichotomum

Clerodendrum trichotomum is a small tree with strong adaptability and fine ornament, which maybe a select for greening tree species in saline land. We set salt treatment test to determine its salt tolerance. Stress from soil NaCl treatments of 0 （the control）, 2, 4, 6, 8 g·kg^-1 on one-year-old C. trichotomum potted seedlings with five replications were studied for their morphology, chlorophyll content, gas exchange characteristics, and water use efficiency（WUE）. The parameters were determined from the second treatment day to the twelfth treatment day. Results showed that as NaCl stress increased and with a prolonged stress time, new shoot and functional leaves faded becoming brown with chlorophyll a （chla）, chlorophyll b （chlb）, chla/chlb, stomatal conductance （Gs）, transpiration rate （Tr）, WUE, and net photosynthesis （Pn） gradually decreasing. Intercellular CO2 concentration （Ci） decreased but later increased; stomatal limitation value （Ls） changes were the opposite of Ci changes. Salt tolerance of C. trichotomum was less than 6 g·kg^-1 in few days. Stomatal limitations mainly caused the decline in the photosynthetic rate of C. trichotomum, whereas in the long run non-stomatal limitations were the primary cause. Ch, 5 fig. 14 ref.]