水分胁迫下臭柏（Sabina vulgaris Ant.）光合特性和色素组成的季节变化

在室内砾耕栽培条件下,通过培养液中加入PEG(Polyethylene glycol 分子量为6000)以调节溶液渗透势,设置对照、弱水分胁迫和强水分胁迫3种处理 (培养液渗透势分别为0.02,-0.1,-0.34 MPa), 从1997年开始对臭柏进行长期干旱胁迫模拟实验.2003年测定了臭柏叶片光合色素和光合特性的季节变化.结果表明:对照区气孔导度季节变化在5月和9月份形成了典型的双峰曲线.尽管对照区的气孔导度明显高于其他两个处理,但日光合量却低于弱水分胁迫区.3个处理Chl a/b的比值在11月至翌年3月的低温期内均升高,以强水分胁迫区的增幅最大,其它月份该比值在3个处理之间没有显著的差异.3个处理的叶绿素总量(Chl a+b)在生长季的5～9月份均有不同程度的上升,但其中以强水分胁迫区增幅最小.在11月至翌年3月的低温期,各处理均大幅提高叶黄素总量(V+A+Z)和热耗散色素比例(A+Z)/(V+A+Z) (V:紫黄质、A:单环氧玉米黄质、Z:玉米黄质);在5～7月份的生长高峰期,各处理则明显降低了叶黄素总量和热耗散色素比例.这种趋势在强水分胁迫区表现的更为显著.

Seasonal changes of photosynthetic characteristics and pigment composition of Sabina vulgaris Ant. under water stress

To explore the eco-physiological adaptation of Sabina vulgaris to drought stress, a drought-controlled experiment was performed using PEG (Polyethylene glycol) with three levels of osmotic potential (0.02, -0.1 and -0.34 MPa, respectively) in the culture solution in the greenhouse for 6 years (1997-2003). The seasonal changes of photosynthetic characteristics and pigment composition were investigated for the whole year in 2003. The pattern of seasonal change in stomatal conductance was shown in bimodal distribution with peaks in both May and September in 2003, and the stomatal conductance in the control was much higher than that of the other two water stress treatments, while the photosynthetic rate of low water stress was the highest among the three treatments. The ratio of chlorophyll a to chlorophyll b (Chl a/b) increased for all three treatments through November to March next year, particularly at the high water stress condition. The total leaf Chl content (Chl a+b) increased for all the three treatments through March to September, and the value was the lowest with the high water stress treatment. The total xanthophyll content (V+A+Z) and (A+Z)/(V+A+Z) were significantly higher in winter (November to March) than in summer (May to July) compared to that in other seasons, which was particularly obvious with high drought treatment.