Light response of photosynthesisand its simulation in leaves of Prunus sibirica L.under different soil water conditions
Light response of photosynthesisand its simulation in leaves of Prunus sibirica L.under different soil water conditions
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作者：
H. Xiaolan
水分亏缺是黄土丘陵沟壑区植被恢复与重建的主要限制因子之一，L.is该地区常见的树种之一，但对水分胁迫下山杏叶片光合特性的研究较少。本研究旨在探讨不同土壤水分含量对山杏光合作用的影响L.to表征山杏光合作用与土壤水分的关系，探讨不同光合模型在模拟不同土壤水分条件下山杏光合作用光响应中的适用性，以进一步了解水分胁迫下山杏的光生理特性，指导黄土丘陵沟壑区山杏的栽培. L.in利用CIRAS-2便携式光合作用测定系统，研究了8种不同土壤水分条件下2年生西伯利亚扁桃叶片光合作用的光响应，并分别采用矩形双曲线模型、非矩形双曲线模型和基于矩形双曲线模型的修正模型对光合作用的光响应曲线进行了拟合和分析。在土壤相对含水量为56.3%~ 80.9%的地区，山杏叶片的光合速率较高，光抑制不明显。光合速率的光响应、表观量子效率、光补偿点和暗呼吸速率均能用3个模型拟合。非直角双曲线模型拟合效果最好;矩形双曲线模型拟合效果最差，当RSWC超过最佳范围时，（56.3%RSWC80.9%）时，强光对山杏叶片有明显的光抑制作用，光合作用显著降低，光饱和点和光合量子效率也显著降低，在此情况下，只有修正的矩形双曲线模型才能较好地拟合光合作用的光响应和主要参数。结果表明，山杏叶片正常光合作用的最适RSWC范围为56.3%~ 80.9%，修正的矩形双曲线模型能较好地拟合各种土壤水分条件下的光合作用光响应曲线和主要参数，矩形双曲线模型和非矩形双曲线模型均能较好地拟合各种土壤水分条件下的光合作用光响应曲线和主要参数。矩形双曲线模型只能拟合最佳土壤水分条件下的光合作用光响应曲线和主要参数。
Water deficit is one of the major limiting factors in vegetation recovery and reconstruction in loess hilly gully region.Prunus sibirica L.is one of the common trees grown in this region.However,studies on characteristics of photosynthesis in leaves of Prunus sibirica L.under water stress are limited. The objective of this study is to explore the effect of different soil water content on photosynthesis in leaves of Prunus sibirica L.to characterize the relationship between photosynthesis of Prunus sibirica L.and soil water content and to explore the applicability of different photosynthetic models in simulating light response of photosynthesis in Prunus sibirica L.under different soil water conditions,which will help us to further understand the photo-physiological characteristics of Prunus sibirica L.under water stress.The results will also help guiding cultivation of Prunus sibirica L.in the loess hilly gully region. By using CIRAS-2 portable photosynthesis system,the light responses of photosynthesis in leaves of two-year-old Prunus sibirica L.were studied under 8 different soil water conditions.And the light response curves of photosynthesis were fitted and analyzed by rectangular hyperbola model,non-rectangular hyperbola model and a modified model based on rectangular hyperbola model. Higher photosynthesis and less obvious photo-inhibition were observed in leaves of Prunus sibirica L grown in the region where the relative soil water contents(RSWC) were from 56.3% to 80.9%.The light response of photosynthesis,the apparent quantum yield(Φ),the light compensation point(LCP) and the dark respiration rate(Rd) were well fitted by the three models.Among the three models,the non-rectangular hyperbola model fitted the data best;the rectangular hyperbola model fitted the data worst.When the RSWC exceeded the optimal range(56.3%RSWC80.9%),obvious photo-inhibition and significant decrease in photosynthesis were observed in leaves of Prunus sibirica L.under strong light,light saturation point and quantum yield of photosynthesis also decreased significantly.Under this circumstance,only the modified rectangular hyperbola model could well fit light response of photosynthesis and the main parameters. The optimal range of RSWC for normal photosynthesis in leaves of Prunus sibirica L was from 56.3% to 80.9%.The modified rectangular hyperbola model could well fit light response curves of photosynthesis and the main parameters under all the different soil water conditions.The rectangular hyperbola model and non-rectangular hyperbola model could only be used to fit light response curves of photosynthesis and the main parameters under the optimal soil water conditions.