低温胁迫对闽楠幼苗形态及生理特性的影响

Effect of Low Temperature on Morphology and Physiology Characteristics of Phoebe bournei Seedlings

为研究闽楠幼苗耐低温胁迫的能力,以闽楠一年生盆栽苗为材料,人工模拟不同的低温环境(10℃、5℃、0℃、-5℃)进行培养试验,以25℃条件下生长的幼苗为对照,观察幼苗叶片在胁迫下的形态变化,并测定其生理生化指标。结果表明,胁迫10d时,5℃和10℃处理的幼苗其叶形、叶色和枝梢形态与对照相比未见明显变化,但0℃处理的幼苗叶片则有明显变化;20d时,10℃条件下闽楠成熟叶片萎蔫下垂并伴有少许叶片脱落现象,而0℃处理的叶片还伴有失绿现象。经过-5℃/24h处理,幼苗叶片失绿且伴有结冰现象;常温恢复1h和12h后,叶片出现反卷、失绿严重、叶片重度萎蔫并脱落的现象。随着胁迫温度的降低和持续长时间的处理,闽楠幼苗叶片细胞质膜透性、SOD酶活性和脯氨酸含量增加,MDA含量先下降后上升,叶绿素含量呈持续下降趋势。经过24h的冻害处理及常温恢复1h和12h,闽楠幼苗叶片细胞质膜透性、叶绿素含量、MDA含量、SOD酶活性和脯氨酸含量呈不同程度的变化趋势。用Logistic方程计算出闽楠幼苗半致死温度为-2.9℃。试验结果说明闽楠幼苗可以抵抗一定程度的低温,但持续20d的冷害和-5℃/24h冻害及常温恢复12h处理,其幼苗叶片的正常代谢及生长发育受到严重影响。

In order to know the endurance ability of Phoebe bournei seedlings under low temperature stress,the morphological characteristics,physiology and biochemistry indexes of Phoebe bournei seedlings were measured with one-year-old potted P. bournei seedlings under different low temperature conditions（ 10℃,5℃,0℃,-5℃） set by artificial simulation,while seedlings at 25℃ as control. The results showed that： there was no obviously change on-leaf shape,leaf color and shoot shape of P. bournei seedlings after 10 d under low temperature stress of 5℃ and10℃. The seedlings appeared wilting and a little drooping under 10℃ stressing on 20 d,however,some leaves lost green under 0℃ stress. After the seedlings were treated at-5℃ for 24 h,the leaves lost green and accompanied with icing phenomena,afterwards,the seedlings were recovered 1 h and 12 h under 25℃,the leaves appeared rewind,lost green seriously,dispirited severely and shredded. As the stress temperature decreased and treatment continued for a longer time,the leaves membrane permeability,SOD activity and proline content increased,chlorophyll content showed a downward trend,and the MDA content increased firstly and then decreased.After treated under-5℃ for 24 h and then recovered 1 h and 12 h under 25℃,the membrane permeability,chlorophyll content,proline content,SOD activity and MDA content of the seedlings varied in trend. With logistic equation,the seedlings semi-lethal temperature was calculated,-2. 9℃. The study indicated that the P. bournei seedlings could endure low temperature stress. However,when the stress time continued 20 d and under-5 ℃ treatment for 24 h as well as recovered 12 h in normal conditions,the seedlings could be seriously affected in terms of physiology and metabolism,even on the growth and development.