Study On The Photosynthetic Characteristics Of Four Varieties Oil-tea Camellia

The oil-tea camellia species including Camellia oleifera, Camellia meiocarpa,Camellia chekiangoleosa and Camellia yuhsienensis are selected to study thephotosynthetic characteristics in normal state by Li-6400XT portable photosynthesissystem.The diurnal variation of net photosynthesis,the light-response characteristicsof photosynthesis,CO₂-response curve of photosynthesis and the seasonalvariationwere tested. Meanwhile,the light response curves of photosynthesis were analyzed byrectangular hyperbola model non-rectangular hyperbola model and a modified modelbased on rectangular hyperbola model.The result showed that:（1）The diurnal variation of net photosynthetic rate of four species oil-tea camelliapresented a single peak curve, and midday depression of photosynthesis did notappear. The maximum net photosynthetic rate of Camellia meiocarpa and Camelliaoleifera was higher than that of Camellia chekiangoleosa and Camellia yuhsienensis.（2）The net photosynthetic rate of four species oil-tea camellia under differentphotosynthetic effective radiatio presented a single smooth curve and the maximumnet photosynthetic rate of Camellia meiocarpa and Camellia chekiangoleosa washigher than that of Camellia oleifera and Camellia yuhsienensis. The rectangularhyperbolic model, nonrectangular hyperbolic model and the modified rectangularhyperbola model could well fit light response curves of photosynthesis and thecoefficient （R2） of each model were above0.9. The transpiration rate of four speciesoil-tea camellia under different photosynthetic effective radiation increased alongwith the light intensity increasing and was not restrained by the strong light. Theintercellular CO₂concentration under different photosynthetic effective radiation ofCamellia oleifera and Camellia chekiangoleosa was higher than that of Camelliameiocarpa and Camellia yuhsienensis.While the water using efficiency of Camelliameiocarpa and Camellia yuhsienensis was higher than Camellia oleifera andCamellia chekiangoleosa.（3）The net photosynthetic rate of four species oil-tea camellia under differentconcentration of CO₂presented a single curve On the whole. The CO₂compensation point of four species oil-tea camellia was between49-66μ mol·mol^ï¹£1.The Camelliaoleifera were hierest and Camellia yuhsienensis were lowest.The CO₂saturationpoint（CSP）of Camellia yuhsienensis was800μ mol·mol^ï¹£1,others were1100μmol·mol^ï¹£1. The apparent carboxylation efficiency（CE）was between0.0127-0.0326μ mol·mol^ï¹£1. The transpiration rate of four species oil-tea camellia under differentCO₂concentration presented first rise after falling and the turning point was about400μ mol· molï¹£1.The intercellular CO₂concentration under different CO₂concentration presented as an opening up parabola.The stomatal conductance ofCamellia chekiangoleosa and Camellia meiocarpa under different CO₂concentrationwas higher than Camellia oleifera and Camellia yuhsienensis.（4）The diurnal variation of net photosynthetic rate of four species oil-tea camelliapresented a single peak curve in April, October and December, while the diurnalvariation of net photosynthetic rate of four species oil-tea camellia presented aBimodal curve in July...