木棉叶片叶绿素荧光参数和SPAD值对干旱胁迫的响应

采用盆栽控水干旱法模拟干旱逆境，对1年生木棉(Bombax ceiba)盆栽苗进行不同程度的胁迫处理，测定干旱胁迫时其叶片叶绿素SPAD值和荧光参数动态变化。结果表明，干旱胁迫下，木棉叶片叶绿素相对含量逐渐降低；初始荧光(Fo)随着干旱程度的加剧而呈上升趋势，而最大荧光(Fm)、潜在光化学效率(Fv /Fo)、最大光化学效率(Fv /Fm)、光化学淬灭系数(qP)和表观光合电子传递速率(ETR)下降，在中度和重度干旱胁迫时差异显著(P＜0.05)；非光化学淬灭系数(NPQ)变化不显著。干旱胁迫导致木棉植株出现光抑制，植株可通过降低光化学淬灭、增加热耗散的形式增强对干旱的适应能力。

Responses of Chlorophyll Fluorescence Parameters and SPAD Value in Leaves of Bombax ceiba to Drought

Four different gradients of drought stress were carried out on one-year-old seedlings of Bombax ceiba by potted simulation drought. The Chlorophyll SPAD value and fluorescence parameters in leaves of seedlings were measured. The results showed that the SPAD reduced slowly with the degree of drought stress increasing, the parameters of initial fluorescence (Fo) showed a rising trend, while maximum fluorescence (Fm), potential activities of PSⅡ (Fv /Fo), maximum photochemical efficiency of PSⅡ (Fv /Fm), photochemical quenching (qP) and relative photosynthetic electron transport rate (ETR) decreased, and they had significant difference under moderate and severe drought stress from slight drought stress and control (P<0.05). But non-photochemical quenching (NPQ) change was not significant among these treatments. With the drought stress increased, the photo-inhibition appeared, B. ceiba could improve adaptability by reducing photochemical quenching coefficient and improving thermal dissipation.