摘要
以黄河三角洲贝壳堤岛3年生杠柳(Periploca sepium)苗木为试验材料,模拟设置贝壳砂生境下的4种水分梯度,利用CIRAS-2型光合作用系统测定杠柳叶片在不同干旱胁迫下的光合作用光响应过程,采用4种光响应模型进行拟合分析,以比较贝壳砂生境干旱胁迫下适宜的光响应模型,探讨最佳光响应模型参数对干旱胁迫的适应规律。结果表明:4种模型对杠柳叶片光合作用光响应过程拟合效果的优劣顺序为:直角双曲线修正模型>非直角双曲线模型>指数模型>直角双曲线模型,后3种模型均为没有极值的函数,故不能很好地拟合光响应曲线光抑制过程,并不能直接求解最大净光合速率(Pnmax)和光饱和点(LSP)。光响应参数拟合效果最佳表现为:非直角双曲线模型的暗呼吸速率(Rd),直角双曲线模型的光补偿点(LCP),直角双曲线修正模型的Pnmax和LSP。4种光响应模型对干旱胁迫具有不同的适应性,直角双曲线修正模型适应各种水分条件,直角双曲线模型和指数模型较适合轻度干旱胁迫条件,非直角双曲线模型较适合重度干旱胁迫条件。随干旱胁迫的加剧,光响应参数表观量子效率(AQY)、Rd和LCP先升高后下降,净光合速率(Pn)、Pnmax和LSP逐渐下降。轻度、中度和重度干旱胁迫下,LSP分别比对照下降5.2%、16.3%和34.5%,Pnmax分别比对照下降17.8%、39.0%和59.0%。水分充足条件下,杠柳叶片光能利用最强,光照生态幅最宽;重度干旱胁迫下,杠柳叶片表现出明显的光饱和、光抑制现象,光能利用减弱,光合能力受到较大限制。
Aims Our objectives were to find the optimal models for different drought stresses by comparing four light response models of photosynthesis in leaves of Periploca sepium growing in sand formed from seashells, investigate the adaptability law of parameters of light response models to drought stresses, and define the adaptability of P. sepium to the shell sand moisture conditions. Methods We used three-year-old P. sepium grown in shell ridge island of China’s Yellow River Delta as experimental material, set up four moisture conditions simulating those in shell sand, measured light responses of photosynthesis in leaves of P. sepium under different drought stresses using CIRAS-2 portable photosynthesis system, and fitted and analyzed the light response curves by four models： rectangular hyperbola, non-rectangular hyper-bola, exponential and modified rectangular hyperbola. Important findings The sequence of fitting effect of the four light response models was in descending order： modified rectangular hyperbola model nonrectangular hyperbola model exponential model rectangular hy-perbola model. This result was related to the latter three models not having extreme values, not fitting the process of light response curve declining after light saturation point （LSP）, and not directly and accurately solving maxi-mum net photosynthetic rate （Pnmax） and LSP. Among them, the non-rectangular hyperbola model best fit dark respiration rate （Rd）, the rectangular hyperbola model best fit light compensation point （LCP） and modified rectangular hyperbola model best fit Pnmax and LSP. The adaptabilities of the four models to different drought stresses varied. The modified rectangular hyperbola model well fit the curves under all the drought stresses, the rectangular hyperbola model and exponential model suited mild drought stress and the non-rectangular hyperbola model suited severe drought stress. The light response parameters, including apparent quantum yield （AQY）, Rd, LCP, Pnmax and LSP, responded to drought stresses differently. AQY, Rd and LCP first increased and then decreased with the aggravation of drought stress, while Pn, Pnmax and LSP decreased gradually. LSP decreased by 5.2%, 16.3% and 34.55% under light stress, moderate stress and severe stress, respectively, in comparison to the control （1556 μmol·m–2·s–1）. Pnmax decreased by 17.8%, 39.0% and 59.0% compared to the control （22.58 μmol·m–2·s–1）. Light use capability of P. sepium leaf was strongest and light ecological amplitude （1520 μmol·m–2·s–1） was wid-est under sufficient water condition; photo-saturation and photo-inhibition occurred significantly, light use capa-bility weakened, and photosynthetic capacity was inhibited seriously under severe stress.
出处
《植物生态学报》
CAS
CSCD
北大核心
2013年第2期111-121,共11页
Chinese Journal of Plant Ecology
基金
国家自然科学基金项目(31100468和41201023)
国家"十一五"科技支撑计划课题(2009BADB2B05)
山东省自然科学基金项目(Y2006D01)
关键词
光响应模型
净光合速率
光合参数
贝壳堤岛
土壤水分
light response model
net photosynthetic rate
photosynthetic parameter
shell ridge island
soil water
