低温胁迫对“繁景”杜鹃生理特性及叶片超微结构的影响

Effects of low temperature stress on physiological characteristics and ultrastructure of “Fanjing” Rhododendron leaves

"繁景"杜鹃为杂交后代优良新种,研究其对低温的耐受能力,为宁波及周边城市将其作为绿化植物提供参考。该研究以一年生杂交后代优良株系"繁景"为材料,采用盆栽试验,利用人工降温的方法,研究不同低温(0℃,-3℃,-6℃,-9℃)对其生长状态、生理生化及叶片超微结构的影响。结果表明:在-3℃和0℃的低温胁迫下,叶绿素含量降低缓慢且与处理前变化不显著,在-9℃和-6℃的低温胁迫下,其叶绿素含量要显著低于处理前和对照组,不同低温处理下,叶片光合速率均呈下降趋势,至试验结束时,光合速率与温度成正比。在-9℃和-6℃低温胁迫下,其叶片相对电导率和丙二醛(Malondialdehyde,MDA)的含量增长最快,且过氧化氢酶(Cata-lase,CAT)、以及超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化物酶(Peroxidase,POD)活性下降幅度最大,在-3℃和0℃低温胁迫下,MDA的含量增长较明显,但可溶性蛋白,CAT,POD及SOD活性变化不明显。温度降低对其叶片超微结构的影响较大,在0℃和-3℃低温胁迫下,其细胞结构正常;在-6℃低温胁迫下,类囊体结构开始模糊,淀粉粒和嗜锇颗粒变大且增多;在-9℃低温胁迫下,细胞膜开始解体,叶绿体被膜破损缺失严重,空洞化程度严重,部分细胞甚至成为空细胞。综合各指标变化情况,杜鹃优良株系能耐受的较低温度为-6℃。因此,杜鹃该优良株系为较耐寒品种,可作为宁波及周边城市良好的杜鹃花绿化候选材料。

As a new kind of hybrid offspring,＂Fanjing＂Rhododendron was studied for its tolerance to low temperature,and it was used as a green plant in Ningbo and surrounding cities. We used the excellent strains of＂Fanjing＂Rhododendron as the material with pot experiment,and the method of artificial cooling to study different low temperatures（ 0,-3,-6 and-9 ℃）,physiological and biochemical effects of growth state and leaf ultrastructure. The results showed that at the temperature-3 ℃ and 0 ℃,the chlorophyll content decreased slowly and before treatment did not change significantly at the temperature-9 ℃ and-6 ℃,the chlorophyll content was significantly lower than that before treatment and the control group,different low temperature treatments,photosynthetic rate of leaves decreased,until the end of the trial when the photosynthetic rate was directly proportional to the temperature. Under-9 ℃ and-6 ℃ low temperature stress,the relative conductivity and malondialdehyde in leaves（ Malondialdehyde,MDA） content increased most rapidly,and catalase（ Cata-lase,CAT）,peroxidase（ Peroxidase,POD） and superoxide dismutase（ Superoxide Dismutase,SOD） activity decreased significantly; at-3 ℃ and 0 ℃ treatment,the content of MDA increased significantly,but soluble protein CAT,POD and SOD activity did not change significantly. Lower temperature had great effect on the ultrastructure of leaves of Rhododendron,when the temperature was at-3 ℃ and 0 ℃,the cell structure was normal; under-6 ℃ treatment,fuzzy starting structure of thylakoid,starch grains and osmiophilic particles become larger and more; under the-9 ℃ treatment,the cell membrane began to disintegrate and chloroplast membrane a serious lack of damage severity,hollowing out,some cells even become empty cells. Comprehensive indicators of changes in the situation,excellent strains of Rhododendron can tolerate a lower temperature of-6 ℃. Therefore,it can be used as a good candidate material for Rhododendron in Ningbo and surrounding cities.