Low spring temperatures often occur during the winter wheat booting stage, when the young ears are very sensitive to cold. In this study, we used two wheat varieties differing in cold sensitivity (sensitive variety Yangmai 18 and tolerant variety Yannong 19) to examine the effect of low temperature on wheat grain number at booting stage. Low temperature stress was simulated in an artificial climate chamber at 4°C for 60 h in 2016 and at 2, 0, or −2°C for 24 h in morphological assays, showing that the development of wheat spikelets was inhibited and floret growth was delayed following low temperature stress. However, an increase in the sucrose content of young panicles was also observed, and the activity of enzymes involved in sucrose metabolism was dynamically altered. Sucrose phosphate synthase activity was enhanced, and sucrose synthase activity significantly increased after treatment at 4 and 2°C, respectively. However, activities of sucrose synthase and invertase decreased with a reduction in temperature. Gene expression assays further revealed downregulation of TaSuS1 expression and upregulation of TaSuS2 , while expression of CWINV was inhibited. Moreover, phytohormone content assays showed an increase in the content of abscisic acid in young wheat ears, but a decrease in the content of auxin and gibberellins. The grain number per spike and 1000-grain weight also showed a downward trend following low temperature stress. Overall, these findings suggest that low temperature at booting induces abscisic acid accumulation in winter wheat, altering the activity of the enzymes involved in sucrose metabolism, which leads to an accumulation of sucrose in the young ears, thereby having a negative effect on wheat production.

High-efficiency flexible perovskite solar cells based on a novel mixed-cation 2D perovskite passivating FA-based perovskite absorber.

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A fast, highly efficient, and ecofriendly extraction method using deep eutectic solvents (DESs) for mechanochemical extraction (MCE) was developed to extract bioactive compounds from plants. Tea leaves containing bioactive compounds such as alkaloids, flavonoids, and catechins were used to evaluate this method. Dozens of DESs and DESs/water mixtures were systematically studied and optimized to select optimized extraction conditions. The results showed that the extractions can be completed within 20 s. Moreover, the developed extraction method is more ecofriendly, faster, gentler, and more efficient than conventional methods. For many compounds, we could simply use the described method without optimization. On the other hand, the target compounds were extracted with various interferences because of the wide ranging high extraction efficiency. Ultrahigh performance liquid chromatography coupled with highresolution mass spectrometry was therefore used for qualitative and quantitative analysis to characterize the efficiency for individual compounds. To avoid the negative effect of DESs on chromatographic separation, the analytical performances of this method, including reproducibility (RSD, n = 5), correlation of determination (r 2 ), and the limit of detection, were determined.

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