Drought is one of the major abiotic stresses affecting the morphological, physiological, and metabolic processes of plants, and hence their growth and production on a global scale. Lucerne (Medicago sativa L.) is one of the most popular pasture species in semi-arid regions and plays a critical role in sustaining agricultural systems in many areas of the world. In order to evaluate the effect of water deficits on the growth and biomass distribution in different tissues of lucerne, plant height, leaf dry weight, leaf number and area, root dry weight, taproot length and lateral root number, and stem dry weight were measured at four stages from the seedling to flowering stages under three water regimes: (i) adequate water supply (minimum soil water content 85% pot capacity (PC)), (ii) moderate water stress (65% PC), and (iii) severe water stress (45% PC), imposed under a rainout shelter. With limited water supply, plant height, leaf number, leaf area and dry weight, taproot length, and total biomass were reduced, while lateral root numbers increased. The number of smaller leaves and root dry weight increased under moderate water stress, whereas severe water stress reduced them. Leaf, stem, and total dry weight were all reduced by the water deficits, but leaf dry weight was reduced the most and root dry weight the least, so there was a redistribution of biomass towards the roots, increasing the root–shoot ratio. These results help us to understand the response of lucerce to water stress and assist in developing a foundation for the sustainable use of lucerne in semi-arid agricultural systems.

The antioxidant enzyme system is the main defense system responsible for maintaining cellular reactive oxygen species (ROS) homeostasis and normal plant growth and development after saline stress. In this study, we identified and characterized the members of the SOD, APX and CAT gene families of the antioxidant enzyme system in Gymnocarpos przewalskii, using plant physiology and molecular biology methods, and analyzed the pattern of enzyme activity in response to NaCl stress. It was found that seven, six and two genes of SOD, APX and CAT gene families, respectively, were expressed in the leaf tissue of G. przewalskii, in which most of the genes were significantly upregulated under NaCl stress, and the enzymatic activities were in accordance with the gene expression. Three positive selection sites in the GpCAT1 gene can increase the hydrophilicity of the GpCAT1 protein, increase the volume of the active site and increase the affinity for H₂O₂, thus improving the catalytic efficiency of GpCAT1. The results of the present study provide new insights for further investigations of the evolution and function of the SOD, APX and CAT gene families in G. przewalskii and their essential roles under salt stress, and the findings will be useful for revealing the molecular mechanism of salt tolerance and breeding of salt-tolerant plants.

Drought is one of the most harmful environmental stresses affecting the physiological, biochemical processes and growth of plants. Lucerne or alfalfa (Medicago sativa L.), one of the most popular pasture species in arid and semi-arid regions, plays a critical role in sustaining agricultural systems in many areas of the world. In order to evaluate the effect of water shortage on water status, biomass distribution and proline content, the relative water content (RWC), biomass and proline concentration in the leaves, stems and roots of lucerne seedlings under three different water regimes were studied in pots under a rainout shelter. The results showed that after water was withheld, the RWC of the different organs decreased significantly; at the same soil water content, the leaf RWC was higher than that of the stem and root. The biomass of the leaves, stems and roots were all reduced by water stress, while the root–shoot ratio increased indicating that the roots were less affected than the leaves and stems. Proline concentration increased with decreasing soil water content with the leaf proline concentration increasing more than that of stems and roots. These results indicate that roots of lucerne seedlings show greater resilience to water deficits than shoots.

For the preservation of ecosystems, including the enhancement of ecological strategies, examining the temporal and geographical variance in ecosystem services (ESs) and land use/land cover change (LUCC) is crucial. Gannan is situated on the upper Yellow River, which is a notable water conservation region with excellent ecological quality, but in the background of the local traditional production mode and rapid economic development, natural disasters, grassland degradation, and other ecological problems occur frequently. The integrated valuing of ecosystem services and tradeoffs (InVEST) model and the patch-generating land use simulation (PLUS) model are combined in this work to assess the spatiotemporal variance in ESs in Gannan. We set up three scenarios in modeling future land use—ecological protection (EP), natural development (ND), and economic development (ED) in 2050—and analyzed and evaluated the drivers of the variation in ESs. In order to reveal the LUCC in Gannan between 1990 and 2020, we predicted the LUCC and ESs spatial distribution characteristics in 2050, explored the correlation between its driving factors, and comprehensively analyzed and propose optimization measures and protection strategies. Through several simulation experiments, the findings indicate the following: (1) the largest percentage of land expansion for construction in Gannan between 1990 and 2020 is 74.53%, and the most noticeable percentage of shrinkage in the sand area is 20.67%; (2) from 1990 to 2020, Gannan’s water yield, carbon storage, soil retention, and habitat quality all changed, by 60 × 10⁸ m³, 0.04 × 10⁸ t, −10.66 × 10⁸ t, and −0.02, respectively; (3) ESs are influenced by a variety of natural and societal variables: the southern and southwestern regions of Gannan are home to the majority of ESs hot spot areas, while the northern region is home to the majority of cold spot areas. This study contributes to the analysis of the developmental traits of Gannan ecosystems and can serve as a model for the preservation of terrestrial ecosystems with comparable environmental traits.