Response characteristic of Cinnamomum migao seedling's photosynthesis to CO2 in different conditions of nitrogen
To exploring the effect of nitrogen on CO2 response Characteristics of Cinnamomum migao leaf.This research determined the CO2 response curve of migao leaf and a series of related photosynthetic parameters which including stomatal conductance(Gs),intercellular CO2 concentration (Ci),transpiration rate (Tr) by used Li-6400 portable Photosynthesis System,and fitted the CO2 response curve of migao leaf by used three models of rectangular hyperbola,non-rectangular hyperbola,modified rectangular hyperbola under the stress of four different concentration of nitrogen.Result showed that:the modified rectangular hyperbola models make up the defect from the rectangular hyperbola models do not consider the curve convexity and do not fit phenomena of CO2 supersaturation's and Net photosynthetic rate (Pn)'s decline,it's photosynthetic parameters close to measured values,obtained CO2 saturation point (CSP) directly.Ci of each migao treated by nitrogen with the increase of leaf chamber CO2 concentration (Ca) appeared a linear upward trend consistently under controlled ambient conditions.Ci increased with the increased concentration of nitrogen and phosphorus at the same value Ca.The change trend of Tr and Gs almost unanimously that performed with the increase of Ci appeared downtrend totally,and with the increase of concentration of nitrogen or performed increasing trend under the same Ci.Pn increased gradually as Ci increases excepted for that Pn declined slightly in high stage of Ci,CSP and Maximum net photosynthetic rate (Pnmax) have been improved and CO2 compensation point (CCP) have been reduced in adding Nitrogen,This phenomena indicated that the adaptation of amplitude from photosynthesis of migao leaf to CO2 can be enhanced,the efficiency of CO2 utilization can be improved,the accumulation of organic matter can be promoted by adding nitrogen.the modified rectangular hyperbola models are the best on fitted the CO2 response curve of migao,the growth of migaos seedling can be promoted by adding nitrogen effectively.