Responses of pigmentation and δ13C in Qilian juniper to cold and drought stresses under natural conditions in the Qilian Mountains,China

The seasonal changes of pigments and stable carbon isotope composition (δ¹³C values) were investigated in needles of Qilian juniper (Sabina przewalskii Kom.) from two typical sites, one drier and the other wetter, in the Qilian Mountains, China. The anthocyanins and rhodoxanthin content from both sites were much higher in winter than in summer. Plant needles contained more carotenoids and xanthophylls in winter at the wetter site, while no seasonal difference appeared at the drier site. However, lower chlorophyll content and higher proline and δ¹³C were observed at the drier site. Average tree height was shorter at the drier site trees than at the wetter site. Our results suggested that under natural conditions, pigmentation in S. przewalskii may serve to improve the energy balance of the photosynthetic apparatus under cold and drought stresses. Proline and δ¹³C could be used as drought indicators for S. przewalskii.