Physiological and growth responses of two dogwoods to short-term drought stress and re-watering

Cornus florida and its cultivars have attracted many attentions by its colorful ornamental features. Suitable moisture condition is a major factor in the success of introduction. However, little is known about dogwoods drought adaptation to seasonal water deficit, and recovery potential from the following rainfall. In this paper, treatment of continuous drought lasted 19 days, followed by re-watering for 7 days was performed on 10-month-old seedlings of C. florida, comparing with native C. kousa. Meantime, well-watered seedlings of two species were regarded as controls. Soil relative water content (SRWC) in stressed seedlings of both dogwoods decreased significantly with drought stress prolonged, and recovered to the normal level after re-watering. As the response to drought stress, significant decline in internal carbon dioxide concentration (C_i), remarkable increment in intrinsic water use efficiency (WUE_i) in C. florida, significant increment in chlorophyll content in C. kousa, and notable decline in leaf relative water content (LRWC), maximum quantum efficiency of PSII photochemistry (F_v/F_m), photochemical quenching (qP), as well as significant increment in malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, soluble sugar content (SSC) in both dogwoods were observed. However, most of physiological variables recovered to the level of control after re-watering. Furthermore, drought stress promoted root volume, root area, root biomass, whereas inhibited seedling height, basal diameter, aboveground biomass, resulting in increase of root/shoot ratio. Our findings indicate that, although C. florida has a weaker performance than C. kousa under drought stress, it can recover to the normal level after re-watering. These results suggest that C. florida and its cultivars possess drought adaptive potential for introducing to southern China.