干旱区生态环境知识资源中心

Net photosynthetic rate (P-N), transpiration rate (E), and stomatal conductance (g(s)) declined from upper leaves to the lower ones during dry and rainy seasons, indicating that long-term carbon budget should take into account P-N variations for different leaf types. Relatively greater P-N in the dry season suggested that this species is more able to maintain higher P-N under drought, but the relatively higher E in the dry season might reduce water use efficiency (P-N/E) for the species. Significant correlations between P-N and g(s) indicated that g(s) may be the critical factor for P-N variability in the desert region.