Vulnerability to drought-induced cavitation in shoots of two typical shrubs in the southern Mu Us Sandy Land, China

Abstract

Salix psammophila and Caragana korshinskii are two typical shrubs in the southern Mu Us Sandy Land of China which are threatened by increasing water deficits related to climate change and large-scale human activities (e.g. coal mining and oil exploitation). In this study, we assessed their vulnerability to xylem embolism and the related anatomical traits in two-year-old regenerated shoots of these two shrubs to understand how they cope with drought environment. We also evaluated the in situ hydraulic safety margins to hydraulic failure from measurements of annual predawn and midday leaf water potentials. The results showed that S. psammophila stems had a higher water transport capacity than C. korshinskii stems. The stem xylem water potentials at 12%, 50% and 88% loss of conductivity were-1.11,-1.63 and-2.15 MPa in S. psammophila, respectively, and-1.37,-2.64 and-3.91 MPa in C. korshinskii, respectively. This suggested that C. korshinskii was more resistant to cavitation than S. psammophila. Compared with S. psammophila, C. korshinskii had shorter maximum vessel length, lower vessel density, smaller conductive area and higher wood density, which may contribute to its more resistant xylem. The in situ hydraulic safety margins indicated that even during the driest periods, both shrubs lived well above the most critical embolism thresholds, and the hydraulic safety margin was wider in C. korshinskii than in S. psammophila, suggesting that the regenerated shoots of both shrubs could function normally and C. korshinskii had greater hydraulic protection. These results provide the basis for an in-depth understanding of the survival, growth and functional behavior of these two shrubs under harsh and dry desert environments.

The response mechanism of the HVA1 Gene in hulless Barley under drought stress

“…Drought is an important environmental constraint that limits the productivity of barley and other crops worldwide (Romanek et al, 2011). The growth and development of plants are restrained under the stress of drought with decreases in net photosynthetic rate, respiration, leaf osmoregulation ability, and cell membrane stability (Li et al, 2016). The most susceptible stages to drought are germination, early seedling growth, and grain filling.…”

Contrasting hydraulic strategies in Salix psammophila and Caragana korshinskii in the southern Mu Us Desert, China

“…The hydraulic traits of the two shrubs were measured during the period from June 1 to July 25, 2014 in twelve randomly selected plants, including ten plants per species in the past studies (Li et al 2016). The morphological parameters of the sampled shrubs are given in Table 1.…”

“…We mainly measured leaf hydraulic traits and daily changes of leaf and stem hydraulic traits in this study. For the stem hydraulic traits, including the stem vulnerability curves and wood density, the data from Li et al (2016) were used as it was assumed that these values did not change across plants within the same field site.…”

“…The data set containing stem vulnerability curves (VC) and wood density used in this study were obtained from Li et al (2016). Briefly, the bench-dehydration method was used to determine the stem VCs.…”

“…Limited researches on the hydraulic properties of these two shrubs indicated that stems of S. psammophila are highly vulnerable to cavitation (Ogasa et al 2013), and that a progressive loss of stem hydraulic conductivity with age in C. korshinskii has been shown to partially induce a decline in the photosynthetic rate of resprouts (Fang et al 2013). In another recent study, the stem hydraulic vulnerability of these two shrubs were compared and it was found that S. psammophila is more vulnerable to embolism than C. korshinskii (Li et al 2016). Nevertheless, neither leaf hydraulic traits and their coordination with stem hydraulic traits within the same plant continuum nor the daily embolism repair in the two species have been involved.…”