低温锻炼后桑树幼苗光合作用和抗氧化酶对冷胁迫的响应

Responses of mulberry seedlings photosynthesis and antioxidant enzymes to chilling stress after low-temperature acclimation

以桑树品种"秋雨"为试验材料,研究了桑树幼苗在低温锻炼、冷胁迫和常温恢复期间的光合作用和抗氧化酶活性的变化.结果表明:12℃3d低温锻炼明显提高了桑树幼苗的抗冷性.3℃3d冷胁迫下,12℃3d低温锻炼后的桑树幼苗叶片净光合速率(Pn)、气孔导度(Gs)和PSⅡ最大光化学效率(Fv/Fm)明显高于对照(未经低温锻炼)处理的桑树幼苗,而且其在常温下的恢复也较对照桑树幼苗迅速.在12℃3d低温锻炼和3℃3d冷胁迫期间,桑树幼苗叶片脯氨酸和可溶性糖含量明显增加,而经低温锻炼的桑树幼苗叶片丙二醛(MDA)含量明显低于未经低温锻炼的桑树幼苗,经低温锻炼的桑树幼苗叶片抗坏血酸过氧化物酶(APX)活性则明显高于未经低温锻炼的桑树幼苗.说明渗透调节物质含量增加和APX活性提高在低温锻炼诱导桑树幼苗的抗冷性上发挥着重要的作用.

Taking the seedlings of mulberry （Morus alba） variety ＇ Qiuyu＇ as test materials, this paper studied the changes of their leaf photosynthesis and antioxidant enzymes during low-temperature acclimation, chilling stress, and normal temperature recovery. The results showed that low- temperature acclimation at 12℃for 3 days markedly increased the cold resistance of mulberry seedlings. After the acclimation, the leaf net photosynthetic rate （ Pn ）, stomatal conductance （ Gs） , and maximum photochemical efficiency of photosystem Ⅱ （ Fv/Fm ） under the chilling stress at 3 ℃ for 3 days increased obviously and recovered rapidly, compared with the control non-acclimation. During the period of the low-temperature acclimation and chilling stress, the leaf proline and soluble sugar contents increased. After the acclimation, the leaf malondialdehyde （MDA） content was ob- viously lower while the leaf ascorbate peroxidase （APX） activity was obviously higher than the control, illustrating that the increase of osmolytes content and APX activity played important roles in the cold resistance of mulberry seedlings.