持续干旱胁迫下外源精胺对红椿幼苗的形态与生理调节效应的影响

Regulation effects of exogenous spermine on morphology and physiology of Toona ciliata seedlings under drought stress

为了掌握持续干旱胁迫下外源精胺（Spm）对红椿幼苗的形态和生理调节效应，本研究以2年生红椿盆栽幼苗为试验对象，在人工遮雨棚中开展干旱胁迫及外源精胺调节试验，试验设置4个持续干旱胁迫处理：（1）对照（土壤相对含水量45％～50％，每天浇水至饱和状态，CK）；（2）轻度干旱胁迫（土壤相对含水量30％-38％，持续干旱7d）；（3）中度干旱胁迫（土壤相对含水量25％-30％，持续干旱14d）；（4）重度干旱胁迫（土壤相对含水量20％-25％，持续干旱21d）。然后，连续3天对轻度、中度和重度干旱胁迫处理喷施外源Spm（浓度为1mmol·L^-1）进行修复调节，并正常管护5天。结果表明：喷施Spin对重度干旱胁迫下植株形态损伤的修复速度远低于轻度和中度干旱胁迫植株；在对照、轻度干旱胁迫（或中度、重度）以及喷施外源Spm调节三者之间，红椿幼苗叶片相对含水量和叶绿素含量均差异极显著（P〈0．01）；在对照、中度干旱胁迫（或重度）以及喷施外源Spm调节三者之间，红椿幼苗叶片相对电导率均差异极显著（P〈0．01）；在对照、轻度干旱胁迫以及喷施外源Spm调节三者之间，红椿幼苗叶片MDA含量和POD含量差异显著（P〈0．05）；在对照、重度干旱胁迫以及喷施外源Spm调节三者之间，红椿幼苗叶片MDA含量和POD含量差异极显著（P〈0．01）；在对照、重度干旱胁迫以及喷施外源Spm调节三者之间，红椿幼苗叶片游离脯氨酸含量差异极显著（P〈0．01）；喷施1mmol·L^-1Spm可修复红椿在遭受干旱胁迫时造成的形态和生理损伤并提高植株的持续抗旱能力，其修复作用对轻度和中度干旱胁迫更为显著。

To understand the morphological and physiological regulation effects of exogenous spermine （Spin） on Toona ciliata Roem. seedlings under drought stress, two-year-old potted seedlings of T. cilliate were adopted as experimental materials, and a drought stress and exoge- nous Spm regulation experiment was carried out under rain shelter by combining persistent drought stress with soil moisture measurement. The experiment contained 4 drought stress treat- ments： control （relative soil water content 45%-50%, watering to saturation state of soil mois- ture every day, CK）, mild （relative soil water content 30%- 38%, persistent drought for 7 days）, moderate （relative soil water content 25%-30%, persistent drought for 14 days）, and severe （ relative soil water content 20%-25%, persistent drought for 21 days）. Afterwards, spra- ying Spm （1 mmol·L^-1） was applied to the seedlings after the mild, moderate, and severedrought treatments for 3 consecutive days, then the seedlings were normally managed for 5 days. The repair effect of exogenous Spm on morphological damage in plants under severe drought stress was much lower than those under mild and moderate drought stress. There were extremely signifi- cant differences in leaf relative water content and leaf chlorophyll content among CK, drought- stress treatment （either mild, moderate or severe） and Spm regulation treatment （P〈0.01）. There was extremely significant difference in leaf relative conductance among CK, moderate- drought-stress treatment （or severe-drought-stress treatment） and Spin regulation treatment （P〈 0.01 ）. Differences in leaf MDA content and POD content were significant （P〈0.05） among CK, mild-drought-stress treatment and Spm regulation treatment and they were extremely significant among CK, severe-drought-stress treatment and Spm regulation treatment （P〈0.01）. The proline content was extremely significantly different among CK, severe-drought-stress treatment and Spin regulation treatment （P〈0.01）. Therefore, we could conclude that 1 mmol·L^-1 exogenous Spm treatment could repair the morphological and physiological damages of T. ciliata seedlings under drought stress and promote the drought resistance ability, and such effects were more obvious in plants under mild and moderate drought stress.