Study on Diurnal Changes of Photosynthetic Characteristics of Juglans regia

Taking Juglans regia‘Liaohe 4'as material,diurnal changes of photosynthetic characteristics were studied by Li-6400 portable photosynthesis analyzer.The results showed that the diurnal changes of the net photosynthetic rate(Pn) in the cultivar exhibited double peak curve at 10:00 and 16:00 respectively and the prime peak was 48.40%higher than the second peak,the maximum photosynthetic rate was 6.1125μmol·m-2·s-1,significant midday depression phenomenon occurred at 14:00;the diurnal changes of the transpiration rate(Tr)in the cultivar displayed double peak curve at 10:00 and 14:00respectively and the first peak higher than the second peak,the maximum transpiration rate was 1.7989mmol·m-2·s-1;during midday,net photosynthetic rate(Pn)and stomatal limitation value(Ls)of walnut generally displayed a declining trend,however,intercellular CO2 concentration(Ci)increased.Therefore,non-stomatal limitation was the major factor influencing photosynthesis of Juglans regia.