光强转换对不同生长环境下桑树叶片光化学效率的影响

以桑树品种‘蒙古桑’为试验材料,利用叶绿素荧光技术研究了光强转换对生长在不同光强下的桑树叶片实际光化学效率(ΦPSⅡ)、电子传递速率(ETR)和非光化学淬灭(NPQ)的影响,分析了非光化学淬灭(NPQ)3个组分的变化.结果表明:当光强从黑暗或弱光转换到自然光条件下,自然光桑树叶片的光量子转化效率高于弱光叶片,ΦPSⅡ、ETR诱导平衡较快,NPQ诱导呈先升后降趋势.自然光叶片在强光下状态转换淬灭组分(qT)占NPQ的18%,而弱光叶片qT仅占NPQ的7%.与弱光桑树叶片相比,自然光桑树叶片可以通过较高的光量子转化效率和较强的调节激发能在PSⅠ和PSⅡ之间的分配能力来适应光强的变化.

Effects of irradiance transition on leaf photochemical efficiency of mulberry under different light conditions

Taking the seedlings of mulberry (Morus alba) variety Menggusang as test materials, and by using chlorophyll fluorescence technique, this paper
 studied the effects of irradiance transition on the leaf active photochemical efficiency (Φ_PSⅡ), apparent electron transport rate (ETR), and non-photochemical quenching (NPQ) under different light conditions, and analyzed the changes of three components of NPQ. When the irradiance was transferred from dark or weak light to sunlight, the photosynthetic quantum efficiency of full light leaves was higher than that of weak-light leaves, the inducible time responses of full-light leaves’ Φ_PSⅡand ETR were faster to reach steady state as compared to those of week-light leaves’, and the induction of full-light leaves’ NPQ had a trend of rapid increase in the first two minutes and slow decrease subsequently. The state transitional quenching component (q_T) of full-light leaves under high light condition made up 18% of the total non-photochemical quenching (NPQ), whereas the q_T of weak-light leaves only amounted to 7% of NPQ, which meant that the mulberry leaves under full-light condition could adapt to the changes of light intensity by means of higher efficiency of photosynthetic quantum and greater contribution to the adjustment of light energy between photosystem Ⅰ (PSⅠ) and photosystem Ⅱ (PSⅡ), compared to the leaves under weak-light condition.