Differential of three fields grown Juniperus species summer drought and cold hardening

ABSTRACT

Background:

Understanding species’ reactions to environmental stressors (cold and drought) and characterizing drought tolerance can help us understand their ecosystem responses related to global change. This study aimed to understand and compare the drought and cold tolerance strategies of Juniperus excelsa, Juniperus foetidissima, and Juniperus oxycedrus, which are found in the Western Mediterranean Region. Water relation parameters [ΨTLP (osmotic potential at turgor loss point), Ψ100 (osmotic potential at full turgor), Ɛmax (bulk modulus of elasticity), V0/DW (symplastic water at the saturated point per dry weight of the shoot), RWC (relative water content)] in summer and winter were determined. Total soluble sugar and photosynthetic pigment content were identified in spring, summer, autumn, and winter.

Results:

J. foetidissima had lower Ψ _TLP and higher Ɛmax in summer than other species. The species had similar Ψ _TLP ¹ Ψ ₁₀₀ ¹ Ɛmax, V0/DW, and RWC in winter. A seasonal change was observed in total soluble sugar and photosynthetic pigment content. Total soluble sugar and photosynthetic pigment contents were related to mean air temperature and total precipitation.

Conclusion:

J. foetidissima was more tolerant to water deficit in the summer, whereas the three species reacted similarly to the cold in the winter.

Keywords:
Drought; water status; cold resistance; soluble sugar; Juniperus; Mediterranean

HIGHLIGHTS

The water relations of Juniperus species were generally different in summer but similar in winter.

All three Juniperus species had lower total soluble sugar content in summer than in winter.

While photosynthetic pigment content was high in all three species in summer, it decreased in winter.

J. foetidissima was more tolerant to water deficit in summer than J. excelsa and J. oxycedrus.