光强对福建马蓝光合特性的影响

以药用植物福建马蓝(Strobilanthes cusia)为材料,研究不同光强对福建马蓝光合特性的影响。结果表明,不同光强(100%自然光照、30%自然光照、6%自然光照)处理下,马蓝叶片的光合速率日变化均呈双峰型曲线。3种光强处理中,以30%自然光强下光合速率最高。与自然光照相比,遮荫条件下(30%自然光照、6%自然光照)马蓝具有较高的初始荧光(Fm)、PSⅡ的光化学活性(Fv/Fo)、原初光能转换效率(Fv/Fm)、光化学量子产额(Yield)、光化学淬灭系数(qP)和较低的非光化学淬灭系数(qN);遮荫条件下,马蓝是通过提高叶片叶绿素a/b含量,降低光补偿点,提高光系统中光反应中心光化学活性,增强系统的光能转换效率来提高光合速率,以弥补弱光条件下光能的不足。试验发现遮荫条件下,光合速率和气孔导度相关度较低,非气孔因素应是遮阴影响马蓝光合的主要因子,同时发现遮荫使得马蓝气孔对于光照强度响应的敏感度显著增加。光强对马蓝叶片药效学成分靛蓝、靛玉红中靛蓝含量影响不显著,100%自然光处理的靛玉红含量大于两个遮荫处理。福建马蓝适宜于30%自然光照条件下的间作套种或林下栽培,对其生长有利。

Effects of different light intensities on Strobilanthes cusia photosynthetic characteristics in Fujian Province

"Jian Indigo" made from stem and leave of Strobilanthes cusia is one of the genuine drugs in Fujian Province. S. cusia original plant occurs in dank conditions and grows in forests or generally shaded conditions. Although light intensity is the main cultivation factor of S. cusia, studies on the characteristics of S. cusia photosynthesis under different light intensities were limited. Hence studies on different light intensities (full sunlight, 30% sunlight and 6% sunlight) were carried out to investigate the effects of light intensity on photosynthetic characteristics of S. cusia in Fujian Province. Results showed that diurnal variations in photosynthetic rates under three treatments tracked di-peak curves. Among the three light intensity treatments, the rate of photosynthesis was highest in the 30% sunlight treatment. Compared with natural light (full sunlight), the 30% and 6% sunlight treatments had higher Fm, Fv/Fo, Fv/Fm, Yield, qP and lower qN. Under shaded conditions, photosynthetic rate of S. cusia increased with increasing chlorophyll a/b and photochemical activity in the light response centre, and decreasing light compensation point. Enhancing light energy conversion efficiency rate in photosynthetic system in compensation of insufficient light energy in low light intensity conditions also increased S. cusia photosynthetic rate. There existed a little correlation between photosynthetic rate and stomatal conductance in S. cusia, which suggested the non-stomatal factors were the main drivers of photosynthesis in shaded conditions. It was further noted that shading significantly increased the sensitivity of stomata to light intensity. While the effect of light intensity on leaf indigo content was not obvious, indirubin content under full sunlight was higher than under shaded conditions. The 30% sunlight treatment in intercropping conditions or under tree shades was most suitable for the growth and medicinal component accumulation of S. cusia in Fujian Province.