干旱胁迫对降香黄檀幼苗光合生理特性的影响

采用温室盆栽方法,设置对照(CK)、轻度(LS)、中度(MS)和重度(HS)干旱胁迫4个水分条件,研究不同水分条件对降香黄檀幼苗光合和生理特性的影响。结果表明:(1)随着干旱胁迫程度增加,降香黄檀幼苗叶片叶绿素总含量总体呈现出下降趋势。(2)降香黄檀幼苗叶片净光合速率、气孔导度、胞间CO2浓度和蒸腾速率随着干旱胁迫强度增加均呈现出先增加后降低趋势,且MS和HS处理下的气孔导度和胞间CO2浓度同时降低,此时幼苗光合能力的下降主要受气孔因素限制。(3)随着干旱胁迫强度的增加,降香黄檀幼苗叶片细胞膜相对透性、丙二醛含量、游离脯氨酸含量和POD活性均呈现出增加趋势,而同期SOD和CAT活性呈现出先升高后降低趋势。可见,降香黄檀幼苗在轻度干旱胁迫下可通过增加叶片保护酶活性来清除活性氧对其组织造成的伤害,但胁迫超过一定程度后保护酶活性下降,表明降香黄檀幼苗的耐旱能力有限。

Photosynthesis Physiological Characteristics of Dalbergia odorifera Seedlings under Drought Stress

A greenhouse experiment was conducted to study the photosynthesis physiological characteristics of Dalbergia odorifera seedlings under water stress.Four treatments were arranged:control(CK),light water stress(LS),moderate water stress(MS) and heavy water stress(HS).The results showed that:(1)Total chlorophyll content of seedlings decreased with the drought stress increased.(2)The net photosynthetic rate,stomatal conductance,intercellular CO₂ concentration and transpiration increased under light drought stress and decreased under heavy drought stress.The stomatal conductance and intercellular CO₂ concentration decreased together at moderate water stress and heavy water stress,which indicated that the decline of photosynthetic capacity was caused by stomatal restriction.(3)The leaf membrane permeability,MDA content,proline content and POD activity increased with the drought stress increased,SOD and CAT activities were tended to increase and then decrease.The protective enzyme activities increased at moderate water stress while decreased at heavy water stress which indicated that drought tolerance of D.odorifera seedlings was limited.