高氯酸钾胁迫对水稻幼苗光合作用及保护酶活性的影响

Effects of KClO_4 stress on photosynthesis and activities of protective enzymes of rice seedling

为研究高氯酸钾污染胁迫对水稻苗期光合作用及保护酶活性的影响,在水培及可控试验条件下,对生长在不同浓度(0 mg/L、20 mg/L、100 mg/L、500 mg/L)KClO4胁迫环境中的水稻幼苗光合参数和保护酶活性等变化进行测定。结果表明:与对照相比,胁迫下水稻幼苗的相对生长速率、相对叶绿素含量、净光合速率(P n)、蒸腾速率(T r)、气孔导度(G s)、气孔限制值(L s)均受到不同程度抑制,而丙二醛(MDA)含量、胞间CO2浓度(C i)和过氧化物酶(POD)活性增加,影响程度总体上随胁迫时间的延长和浓度的增高而增大。超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性呈先升后降的趋势。POD活性对胁迫响应最为敏感,至第7 d时20 mg/L、100 mg/L和500mg/L KClO4胁迫处理POD活性分别达到对照的2.07、2.57和2.70倍。相关分析结果表明,相对生长速率与P n、MDA含量、POD及SOD活性呈显著或极显著相关,P n与MDA含量、POD和SOD活性呈显著相关。以上结果说明KClO4胁迫所致水稻幼苗净光合速率下降主要由于非气孔因素的限制,活性氧代谢平衡失调是导致胁迫下水稻生长受抑、光合能力下降的主要原因之一,POD活性等可作为高氯酸钾胁迫伤害的敏感指标。

In order to explore the effects of KClO4 stress on photosynthesis and the activities of antioxidative protective enzymes of aquatic plant, rice seedlings （Oryza sativa L. ） were treated by nutrient solution with different concentrations （0 mg/ L, 20 mg/ L, 100 mg/ L, 500 mg/ L） of KClO4 under the controlled conditions. The relative growth rate （RGR）, the relative chlorophyll content （SPAD）, net photosynthetic rate （Pn）, stomatal conductance （Gs）, transpiration rate （Tr）, stomatal limitation （Ls） of rice seedlings with perchlorate treatment were inhibited at different degrees compared with the control（no perchlorate）, while the intercellular CO2 concentration, matlondialdehyde （MDA） content and POD activity was increased. The effects of KClO4 stress increased progressively with the climbing of concentration and extersionof time. The activities of SOD and CAT ascended firstly and descended afterwards. POD was the most sensitive to the stress, and after treating for 7 d, the activities of rice seedling in 20 mg/ L, 100 mg/ L and 500 mg/ L KClO4 stress treatments were 2.07, 2. 57 and 2. 70 times as much as the control, respectively. There were significant correlations between RGR and SPAD, Pn, MDA content, SOD, POD activities, and between Pn and MDA content,SOD, POD activities. All these results suggested that the decrease of Pn mainly resulted from non-stomatal limitation, and the imbalance of active oxygen metabolism was the main causation leading to the growth inhibition and the decrease of pho-tosynthetic capacity. POD activity could be a sensitive index for the damage by KClO4 stress.