水分胁迫对油松生理活性的影响

为研究油松幼苗对水分胁迫的生理响应,探讨油松幼苗的抗旱耐病机制,以3年生油松幼苗为试验材料,采用盆栽控水试验方法,设置T_1(土壤含水量20%以上)、T_2(土壤含水量10.1%~20%)、T_3(土壤含水量5.1%~10%)和T_4(土壤含水量5%以下)4个水分梯度,测定不同水分胁迫条件下SOD和PPO的含量及变化规律。结果表明,各处理油松针叶SOD活性均随胁迫时间的延长呈先上升后下降再上升的趋势,水分胁迫6天后,其SOD活性显著下降。相同时间下,T_1和T_2的SOD活性与对照组无显著性差异,T_3和T_4的SOD活性显著低于对照(P0.05)。各处理油松针叶PPO活性均随胁迫时间的延长呈先上升后下降的趋势,T_1的PPO活性在9天后下降,T_2、T_3和T_4均在12天后下降,说明土壤含水量在20%以上时,油松的自我修复能力较强,所需修复时间较短。相同胁迫时间下,土壤含水量在10%以上时,PPO活性随水分胁迫的加剧而升高,土壤含水量在10%以下时,PPO活性降低,说明过度胁迫时,酶活性降低。

Effect of Water Stress on Physiological Activity of Pinus tabulaeformis

The paper aims to study the physiological responses of Pinus tabulaeformis seedlings to water stress and discuss drought resistance mechanism. In the present investigation, activities of superoxide dismutase (SOD) and polyphenol oxidase (PPO) of Pinus tabulaeformis needles were analyzed and determined. Needles obtained from 3 years seedlings which were planted in the flowerpots. With water controlling, the soil water content of each treatment was established (T1: over 20%; T2: 10.1%-20%; T3: 5.1%-10%; T4: under 5%). The activities of SOD and PPO were determined by colorimetric analysis every 3 days. The results showed that: along with the stress time, the SOD activity increased at first and reached the maximum on the 6th day, then decreased, while there was a rebound phenomenon on the 12th day. Under the same time of drought stress, the SOD activity showed no significant difference among T1, T2 and control group, while those of T3 and T4 were significantly lower than that of the control treatment (P <0.05). The PPO activity increased first then decreased with water stress time. The PPO activity of T1 decreased after 9 days, while that of T2, T3 and T4 decreased after 12 days. It proved that Pinus tabulaeformis had stronger self-repair ability and could repair itself in a short time when the soil water content was over 20%. The PPO activity increased along with the degree of water stress when soil water content was over 10%, while it decreased when soil water content was less than 10%,indicating that enzyme activity decreased when the water stress was excessive.