以林下阴生蕨类植物对马耳蕨为材料,采用盆栽试验比较了全光照和阴棚生境下对马耳蕨对强光的光合响应特征,以探讨其光适应机制。结果显示:(1)与荫棚条件下相比,全光照下对马耳蕨叶片叶绿素a(Chl a)、叶绿素b(Chl b)及叶绿素(a+b)[Chl(a+b)]含量分别显著下降了48.3%、28.2%、40.0%,而其类胡萝卜素(Car)和总黄酮含量分别显著增加了158.3%、93.9%;(2)全光照下对马耳蕨叶片PSⅡ最大光能转化效率(Fv/Fm)、初始荧光(F0)、PSⅡ潜在活性(Fv/F0)、PSⅡ光能捕获效率(Fv′/Fm′)、光化学淬灭系数(qP)分别比荫棚的下降了3.7%、23.4%、9.5%、2.5%、3.2%;(3)随着光照强度的增加,全光照下对马耳蕨表观电子传递速率(rETR)及热耗散(qN)上升幅度较荫棚显著提高。研究发现,经过一定时期的光适应,通过减少对光能的捕获、降低PSⅡ反应中心活性及光能转化效率、提高光合能力、增强热耗散能力以及增强活性氧的清除能力,阴生植物对马耳蕨的光合作用可适应高光生境;在无水分胁迫条件下,全阳光照不会导致阴生植物对马耳蕨的光合作用发生光损害。
Aftre exposing to full sunlight photosynthetic responses of an sciophillic fren Polystichum tsus-simense were studied in a pot experiment,acclimation mechanism of its photosynthese to higher light intensity was addressed.The results showed:(1)Compared to growing in shady,the contents of Chl a,Chl b and Chl a+b of P.tsus-simense growing full sunlight decreased by 48.3%,28.2% and 40.0% respectively.The contents of carotenoids and total flavonoids increased by 158.3% and 93.9% respectively;(2)Values of Fv/Fm,F0,Fv/F0,Fv′/Fm′ and qP decreased by 3.7%,23.4%,9.5%,2.5% and 3.2% respectively;(3)With increasing light intensity,the value of rETR and qN of plants in full sunlight increased much more than those under shady shed.The research found that after a certain period of acclimation P.tsus-simense was able to adapt to grow in full sunlight by reducing light capture,lowering PSⅡ activity,raising PSⅡ efficiency,intensifying quenching dissipation,and enhancing active oxygen elimination.The study suggested that full sunlight could not cause a photodamage in P.tsus-simense without water stress.