Photosynthetic characteristics in Camellia oleifera clones at fruit maturation stage

In order to learn yield characteristics in new variety of Camellia oleifera from photosynthetic physiology aspect,diurnal changes of net photosynthetic rate(Pn) and transpiration rate(Tr) were studied comparatively with LI-6400P portable photosynthetic system,taking high-yield variety,medium-yield variety and ordinary variety in C.oleifera clones as materials.The results showed that all Pn diurnal change curves were of single peak type,Midday depression phenomenon of photosynthesis didn't occur in all varieties,and there were significant differences among Pn of three varieties.All Tr diurnal changes curves were of single peak type,while all diurnal change curves of water use efficiency were of U type.The maximum Pn of three varieties was 11.574-14.040 μmol·m-2s-1,their light saturation points was 369-500 μmol·m-2s-1,and their light compensation point was 19-23 μmol·m-2s-1.The results of multiple regression analysis showed that the main factor influencing Pn of the high-yield variety was stomatal conductance,the main factors influencing Pn of the medium-yield variety were photosynthetic active radiation and CO2 concentration,and the ordinary variety was mainly influenced by intercellular CO2 concentration.