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Leymus chinensis is a dominant and most promising grass species in the Songnen Grassland of Northern China. Experiments were conducted to determine the effect of temperature, salinity, alkalinity and their interactions on seed germination. Seeds were germinated at four alternating temperatures (10-20, 15-25, 20-30 and 25-35°C), with saline stress (9:1 molar ratio of NaCl:Na 2-SO 4 ) and alkaline stress (9:1 molar ratio of Na 2 CO 3 :NaHCO 3 ). Germination percentage and rate were inhibited by either an increase or decrease in temperature from the optimal temperature range of 20-30°C, and were also inhibited by an increase in salinity and alkalinity at all temperatures. The inhibitory effects of high salinity on germination were greater at 25-35°C, but seeds were subjected to more stress even though the alkalinity was low under this temperature. Recovery percentage was highest at 400 mM M salinity at 20-30°C, but only at 100 mM M alkalinity, and 25-35°C also resulted in lower recovery percentage under both stresses. Results suggest that saline stress and alkaline stress have different impacts on seed germination and that saline-alkaline tolerance of L. chinensis seeds is affected by the interactions of temperature and salinityalkalinity. Early July sowing in the field is recommended when temperature is optimal and salinity-alkalinity concentrations are reduced by the high rainfall.

Soil alkalization is a major environmental threat that affects plant distribution and yield in northeastern China. Puccinellia tenuiflora is an alkali-tolerant grass species that is used for salt-alkali grassland restoration. However, little is known about the molecular mechanisms by which arbuscular mycorrhizal fungi (AMF) enhance P. tenuiflora responses to alkali stress. Here, metabolite profiling in P. tenuiflora seedlings with or without arbuscular mycorrhizal fungi (AMF) under alkali stress was conducted using liquid chromatography combined with time-of-flight mass spectrometry (LC/TOF-MS). The results showed that AMF colonization increased seedling biomass under alkali stress. In addition, principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) demonstrated that non-AM and AM seedlings showed different responses under alkali stress. A heat map analysis showed that the levels of 88 metabolites were significantly changed in non-AM seedlings, but those of only 31 metabolites were significantly changed in AM seedlings. Moreover, the levels of a total of 62 metabolites were significantly changed in P. tenuiflora seedlings after AMF inoculation. The results suggested that AMF inoculation significantly increased amino acid, organic acid, flavonoid and sterol contents to improve osmotic adjustment and maintain cell membrane stability under alkali stress. P. tenuiflora seedlings after AMF inoculation produced more plant hormones (salicylic acid and abscisic acid) than the non-AM seedlings, probably to enhance the antioxidant system and facilitate ion balance under stress conditions. In conclusion, these findings provide new insights into the metabolic mechanisms of P. tenuiflora seedlings with arbuscular mycorrhizal fungi under alkali conditions and clarify the role of AM in the molecular regulation of this species under alkali stress.

Entropy changes due to magnetostructrual phase transition in Gd5SixGe4−x intermetallics have been studied based on a systematic analysis of experiment data and mean-field theory calculations. It is found that the magnetic and lattice entropy changes have the same sign. Further analysis indicates that the main entropy change (∼60%–∼80%) comes from the field-induced change of the magnetic order, while the rest arise from the entropy difference of the two crystallographic modifications joined by the structural transition, probably due to the variation of the lattice vibration mode. The present work reveals the importance of lattice entropy for a system experiencing a first-order transition.

Effects of salt (NaCl : Na 2 SO 4 ) and alkali (NaHCO 3 : Na 2 CO 3 ) stresses on the contents of inorganic ions and organic solutes in wheat shoots were compared to explore the physiological responses and adaptive strategies of wheat to these stresses. Wheat significantly accumulated Na + and simultaneously accumulated Cl , soluble sugars and proline to maintain osmotic and ionic balance under salt stress. Compared with salt stress, the high pH from alkali stress enhanced Na + accumulation and affected the absorption of inorganic anions. To maintain ionic and osmotic balance, wheat accumulated organic acids, soluble sugars and proline. The accumulation of Cl ) and organic acids was the main difference in the physiological responses and adaptive mechanisms to salt and alkali stresses, respectively.

Understanding how the biomass production and clone growth of perennial grasses respond to summer warming is crucial for understanding how grassland productivity responds to global warming. Here, we experimentally investigated the effects of summer warming on the biomass production and clonal growth of potted Leymus chinensis in a phytotron. Summer warming significantly decreased the biomass of both parent and daughter shoots, slightly increased the belowground biomass, and lead to a significant increase in root : shoot ratio. Warming significantly increased the total belowground bud number and decreased the daughter shoot number. Importantly, the proportions of each type of bud changed; vertical apical rhizome buds decreased, while horizontal rhizome buds increased in number. The change in proportions of each type of bud is closely related to the decrease in daughter shoot number, rhizome number and length, as well as the decrease in aboveground biomass and increase in belowground biomass. These results indicate that, as a rhizomatous, perennial grass, L. chinensis adopts a selective growth strategy that reduces the energy allocated to aboveground growth and emphasises the development of belowground organs. The implication is that continued summer warming, will further reduce the aboveground biomass production of temperate grasslands dominated by rhizomatous, perennial grasses. Inevitably, species that depend on these grasses for forage will suffer should global climate warming continue.

We evaluated the contribution of arbuscular mycorrhizal fungi to the growth, ion content, and solute accumulation of Leymus chinensis seedlings under salt–alkali stress and nitrogen deposition.