We aimed to investigate the water use strategies and the responses to water shortages in Glycyrrhiza uralensis, which is a dominant species in the desert steppe. Water stress gradients included control, mild, moderate, and severe. The time intervals were 15, 30, 45, and 60 d. Our study suggested that with the aggravation of water stress intensity, the total biomass of Glycyrrhiza uralensis gradually decreased and allometric growth was preferred to underground biomass accumulation. From 30 d and mild to moderate water stress, the water potential (WP) of leaves decreased considerably compared to the CK. The relative water content (EWC) decreased over time and had a narrow range of variation. Proline (PR) was continuously increased, then declined at 45–60 d under severe and more severe water stress. The δ¹³C values increased in all organs, showed roots > stems > leaves. The net photosynthetic rate (Pn) and transpiration rate (Tr) decreased to varying degrees. The instantaneous water use efficiency (WUEi) and limiting value of stomata (Ls) increased continuously at first and decreased under severe water stress. Meanwhile, severe water stress triggered the most significant changes in chloroplast and guard cell morphology. In summary, Glycyrrhiza uralensis could maintain water content and turgor pressure under water stress, promote root biomass accumulation, and improve water use efficiency, a water-conservation strategy indicating a mechanism both avoidable dehydration and tolerable drought.

Grass species have a range of strategies to tolerate soil water restriction, which are linked to the environmental conditions at their site of origin. Climate change enhances the relevance of the functional role of anatomical attributes and their contribution as water stress tolerance factors. Morpho-anatomical traits and adjustments that contribute to drought resistance in Lolium perenne L. (Lp) and Bromus valdivianus Phil. (Bv), a temperate humid grass species, were analysed. The structure of the leaves and pseudostems (stems only in Lp) grown at 20–25% field capacity (FC) (water restriction) and 80–85% FC (control) were evaluated by making paraffin sections. In both species, water restriction reduced the thickness of the leaves and pseudostems, along with the size of the vasculature. Bv had long and dense leaf hairs, small and numerous stomata, and other significant adaptive traits under water stress, including thicker pseudostems (p ≤ 0.001), a greatly thickened bundle sheath wall (p ≤ 0.001) in the pseudostem to ensure water flow, and a thickened cuticle covering on leaf surfaces (p ≤ 0.01) to avoid water loss. Lp vascular bundles developed throughout the stem, and under water restriction the xylem vessel walls were strengthened and lignified. Lp leaves had individual traits of a ribbed/corrugated-shaped upper surface, and the stomata were positioned to maintain relative humidity outside the leaf surface. Water restriction significantly changed the bulliform cell depth in Lp (p ≤ 0.05) that contributed to water loss reduction via the curling leaf blade. This study demonstrated that the two grass species, through different morphological traits, were able to adjust their individual tissues and cells in aboveground parts to reach similar physiological functions to reduce water loss with increased water restriction. These attributes explain how both species enhance persistence and resilience under soil water restriction.

Objective: Indigofera bungeana is a shrub with high quality protein that has been widely utilized for forage grass in the semi-arid regions of China. This study aimed to enrich the currently available knowledge and clarify the detailed drought stress regulatory mechanisms in I. bungeana, and provide a theoretical foundation for the cultivation and resistance breeding of forage crops. Methods: This study evaluates the response mechanism to drought stress by exploiting multiple parameters and transcriptomic analyses of a 1-year-old seedlings of I. bungeana in a pot experiment. Results: Drought stress significantly caused physiological changes in I. bungeana. The antioxidant enzyme activities and osmoregulation substance content of I. bungeana showed an increase under drought. Moreover, 3,978 and 6,923 differentially expressed genes were approved by transcriptome in leaves and roots. The transcription factors, hormone signal transduction, carbohydrate metabolism of regulatory network were observed to have increased. In both tissues, genes related to plant hormone signaling transduction pathway might play a more pivotal role in drought tolerance. Transcription factors families like basic helix-loop-helix (bHLH), vian myeloblastosis viral oncogene homolog (MYB), basic leucine zipper (bZIP) and the metabolic pathway related-genes like serine/threonine-phosphatase 2C (PP2C), SNF1-related protein kinase 2 (SnRK2), indole-3-acetic acid (IAA), auxin (AUX28), small auxin up-regulated rna (SAUR), sucrose synthase (SUS), sucrosecarriers (SUC) were highlighted for future research about drought stress resistance in Indigofera bungeana. Conclusion: Our study posited I. bungeana mainly participate in various physiological and metabolic activities to response severe drought stress, by regulating the expression of the related genes in hormone signal transduction. These findings, which may be valuable for drought resistance breeding, and to clarify the drought stress regulatory mechanisms of I. bungeana and other plants.

Intensive annual forage cultivation via diversified sowing can increase resource-use efficiency and meet the food requirements of the growing population. However, increasing cultivation time could increase energy demands and production costs with accompanying environmental hazards, such as greenhouse gas (GHG) emissions. A 2-year field experiment including three cropping systems (forage oat monoculture [O], forage oat–common vetch mixed-cropping [O/V], and common vetch monoculture [V]) and two sowing dates (spring and summer) was conducted to comprehensively assess productivity performance, energy utilization, and ecological efficiency under a cereal–legume mixed system over two sowing seasons in Northwestern China. The average system dry matter yield and economic benefit in the mixed system increased by 70.9% and 132.6%, respectively, compared to those of the monoculture system. The application of a mixed-cropping system increased energy efficiency and the ecoefficiency index (EEI) by 61.4% and 132.3%, respectively, with a decline in GHG emission intensity (GHGI) by 49.9%. Spring sowing increased average forage productivity and economic benefit by 9.3% and 18.6%, respectively, with a 23.0% decline in GHGI compared with that engendered by summer sowing. However, there was no correlation between the mixed-cropping system and single sowing date, and the average dry matter yield, economic benefit, and GHGI of the mixed-cropping system were 7.8 t ha⁻¹, 1478.4 USD ha⁻¹, and 0.3 kg CO₂e kg⁻¹, respectively. Furthermore, compared with the monoculture system, the combination of spring and summer seasons under the mixed-cropping system could increase the average annual system forage productivity, economic benefit, and EEI by 37.0%, 49.9%, and 53.1%, respectively, while reducing GHGI by 48.4%. This study demonstrates that the mixed forage oat and common vetch during spring and summer was the sustainable cropping system that achieved high system productivity, good economic returns, high energy utilization, and low environmental risk in Northwestern China.