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Abstract [Objective] Drought stress seriously affects the yield and quality of medicinal plants. This study aims to reveal the physiological mechanism of exogenous calcium in alleviating drought-induced damage in Platycodon grandifloras, which can provide a basis for using exogenous calcium to improve drought resistance and medicinal quality of P . grandiflorus in arid and semi-arid area. [Methods] With P . grandiflorus seedlings as materials, a pot experiment was conducted to explore the effects of exogenous calcium on the growth, photosynthetic gas exchange parameters, antioxidant enzyme activity, and medicinal quality of P . grandiflorus seedlings under drought stress by foliar spraying of 10 mmol/L CaCl2. [Results] (1) Exogenous calcium significantly increased root length and dry and fresh biomass of P . grandiflorus under drought stress. It significantly increased the stomatal aperture, chlorophyll a content, total chlorophyll content, carotenoid content, net photosynthetic rate, stomatal conductance, and transpiration rate by 30.28%, 57.67%, 44.44%, 100.33%, 89.53%, 60.00%, and 83.11%, respectively, in P . grandiflorus leaves under drought stress. (2) Exogenous calcium effectively reduced the content of malondialdehyde and hydrogen peroxide in P . grandiflorus leaves under drought stress, which was significantly reduced by 13.82% and 18.66%, respectively, compared to drought stress. Exogenous calcium increased the superoxide dismutase, superoxide dismutase, and catalase activities in P . grandiflorus leaves by 25.43%, 7.90%, and 33.92%, respectively, and also increased the soluble protein content in roots compared with drought stress. (3) Exogenous calcium significantly increased the levels of latycodin-D, polysaccharides, total flavonoids, and free amino acids in P . grandiflorus roots by 35.34%, 34.87%, 4.19%, and 6.52%, respectively, under normal conditions. Under drought stress, the levels were significantly increased by 10.94%, 7.53%, 6.07%, and 5.78%, respectively. (4) N, P, K, Ca, Cu, and Mn contents in the aboveground and underground parts of P . grandiflorus were significantly reduced under drought stress, while they were increased to varying degrees under exogenous calcium treatment. [Conclusion] Spraying 10 mmol/L CaCl2 could enhance the antioxidant system activity and osmotic regulation ability in P . grandiflorus leaves in arid environment, increase the content of photosynthetic pigments and photosynthetic performance, synergistically promote the accumulation of secondary metabolites and mineral elements, improve the quality of medicinal parts, and alleviate the damage of P . grandiflorus seedlings under drought stress.

Drawing on Critical Metaphor Analysis, this study investigates major metaphors of the COVID-19 pandemic used by the Chinese government in the specific genre of news picture. It examines patterns of metaphor use in the first year of the pandemic in China and explains how and why the government employs the identified metaphors in the Chinese political context. Results reveal that pandemic metaphors (45%) are not as widely used in news pictures as presumed, the vast majority (95%) are rendered in verbal mode, and the most salient metaphors used in news pictures are the UP/DOWN (spatial), WAR, FAMILY, and COMPETITION metaphors. This study then addresses how COVID-19 metaphors are used in the Chinese political context and claims that the Chinese government uses specific metaphors with persuasive and ideological functions. The WAR metaphor aids comprehension of abstract concepts of the pandemic treatment, the FAMILY metaphor fosters empathy among Chinese individuals to counter blame and discrimination in society, UP/DOWN (spatial) and COMPETITION metaphors stimulate action to overcome the common "enemy." WAR and FAMILY metaphors also contribute to the construction of a greater sense of collectivism and play a crucial role in fostering a positive national identity. Implications, limitations and some directions for future research are suggested.

With the proposal and development of Generative Adversarial Networks, the great achievements in the field of image generation are made. Meanwhile, many works related to the generation of painting art have also been derived. However, due to the difficulty of data collection and the fundamental challenge from freehand expressions, the generation of traditional Chinese painting is still far from being perfect. This paper specialises in Chinese art painting generation of flowers, which is important and classic, by deep learning method. First, an unpaired flowers paintings data set containing three classic Chinese painting style: line drawing, meticulous, and ink is constructed. Then, based on the collected dataset, a Flower‐Generative Adversarial Network framework to generate multi‐style Chinese art painting of flowers is proposed. The Flower‐Generative Adversarial Network, consisting of attention‐guided generators and discriminators, transfers the style among line drawing, meticulous, and ink by an adversarial training way. Moreover, in order to solve the problem of artefact and blur in image generation by existing methods, a new loss function called Multi‐Scale Structural Similarity to force the structure preservation is introduced. Extensive experiments show that the proposed Flower‐Generative Adversarial Network framework can produce better and multi‐style Chinese art painting of flowers than existing methods. [ABSTRACT FROM AUTHOR]