Photosynthetic daily dynamics of Chenopodium glaucum and Myosoton aquaticum in Guizhou rocky desertification area

The photosynthetic diurnal change characteristics of Chenopodium glaucum and Myosoton aquaticum were studied in sunny days in karst rocky desertification areas of Guizhou Province with Britain Lcpro+photosynthetic apparatus. The daily mean values of net photosynthetic rate (Pn) of C. glaucum and M. aquaticum were 9.06 and 4.25 μmol CO2·m-2·s-1, respectively. The transpiration rates (Tr) and the water use efficiency (WUE) of these two plants were 3.47 and 3.23 mmol H2O·m-2·s-1 and 2.06 and 1.23 μmol CO2·mmol-1, respectively. C. glaucum had high Pn, Tr and WUE whereas M. aquaticum had low Pn, Tr and WUE which suggested that C. glaucum was more suitable for karst rocky desertification areas with drought and shortage of water.