Seasonal variation and correlation with environmental factors of photosynthesis and water use efficiency of Juglans regia and Ziziphus jujuba.
Both the photosynthetic light curves and CO(2) curves of Juglans regia L. and Ziziphus jujuba Mill. var. spinosa in three seasons were measured using a LI-6400 portable photosynthesis system. The maximal net photosynthetic rate (A(max)), apparent quantum efficiency(phi), maximal carboxylation rate (V(cmax)) and water use efficiency (WUE) of the two species were calculated based on the curves. The results showed that A(max) of J. regia reached its maximum at the late-season, while the highest values of A(max) of Z. jujuba occurred at the mid-season. The A(max) of J. regia was more affected by relative humidity (RH) of the atmosphere, while that of Z. jujuba was more affected by the air temperature. Light saturation point (LSP) and Light compensation point (LCP) of J. regia had a higher correlation with RH of the atmosphere, those of Z. jujuba, however, had a higher correlation with air temperature. V(cmax) of both J. regia and Z. jujuba had negative correlation with RH of the atmosphere. WUE of J. regia would decrease with the rise of the air temperature while that of Z. jujuba increased. Thus it could be seen that RH, temperature and soil moisture had main effect on photosynthesis and WUE of J. regia and Z. jujuba. Incorporating data on the physiological differences among tree species into forest carbon models will greatly improve our ability to predict alterations to the forest carbon budgets under various environmental scenarios such as global climate change, or with differing species composition.
Yang
Hai-Bo
HB
Laboratory of Forest Ecology and Global Changes, School of Life Sciences, Nanjing University, Nanjing 210093, China.
An
Shu-Qing
SQ
Sun
Osbert-Jianxin
OJ
Shi
Zuo-Min
ZM
She
Xin-Song
XS
Sun
Qing-Ye
QY
Liu
Shi-Rong
SR
D002245:Carbon Dioxide / Q000378:metabolism; D004777:Environment; D031324:Juglans / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D010788:Photosynthesis / Q000528:radiation effects; D018526:Plant Transpiration / Q000528:radiation effects; D012044:Regression Analysis; D012621:Seasons; D014867:Water / Q000378:metabolism*; D031957:Ziziphus / Q000502:physiology* / Q000528:radiation effects
D014867:Water; D002245:Carbon Dioxide