Different adaptive responses of leaf physiological and biochemical aspects to drought in two contrasting populations of seabuckthorn

Abstract

Two contrasting populations of seabuckthorn ( Hippophae rhamnoides L.) from western China were employed to study their differences in adaptive responses to drought. The Daofu population was from a wetter upland climate region, whereas the Dingxi populations was from a drier lowland climate region. A completely randomized design with two factors, two populations and two watering regimes (100% and 25% of the soil water holding capacity), was used. In both populations, drought significantly decreased growth and the net photosynthesis rate (A), and significantly increased the root/shoot ratio (RS), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX) and ascorbate peroxidase (APX) activities, and abscisic acid (ABA) and proline contents. Compared with the Daofu population, drought induced a greater RS value, higher CAT, GPX, and APX activities, and a higher ABA content in the Dingxi population, whereas the gas exchange traits, for example, the stomatal limitation value (LS) and intercellular CO2 concentration (Ci), were less responsive to drought in the Dingxi population. The two populations may have developed different strategies to tolerate drought, such as different pathways to dissipate excess absorbed light energy, to resist oxidative stress, and to keep water status. Such factors enable the Dingxi population to tolerate drought better than the Daofu population.