Drought is a major abiotic stress that restricts agricultural production. It not only limits the growth and development of crops, but also affects the delicate balance between plants, rhizosphere microorganisms and root exudates, which is crucial for plant growth and soil health. Therefore, in-depth study of the complex relationship between the three under drought stress will provides scientific basis and technical support for sustainable agricultural development and national food security production. In this paper, the research results on the exudative components and contents of root exudates and the differential changes of rhizosphere microbial communities after drought stress in plants both domestically and internationally were summarized. The recruitment of beneficial microorganisms by root exudates in response to drought stress was analyzed. The mechanism and physiological process of plant growth-promoting rhizobacteria to help plants improve drought tolerance were discussed. The interaction and mutual feedback relationship among host plants, root exudates and rhizosphere microorganisms under drought stress were summarized. On this basis, the changing patterns of root exudates under drought stress, the mechanism of plant drought tolerance, and the key scientific issues and research prospects of the effects of root exudates on rhizosphere microorganisms were proposed, aiming to provide theoretical basis and references for studying and applying methods to improve rhizosphere microbial communities in order to enhance plant drought resistance.
The warming trend of the global climate system continues, and the impact on natural ecosystems and water resources continues to rise, aggravating the already fragile global water resources. At this background, as a potential water resource, non-precipitation water (NPW) in arid area plays an important role in the maintenance of ecosystem and land surface water balance in arid area. Therefore, based on the present results of international research on NPW, the development process of NPW is summarized. The observation methods, variation characteristics, formation mechanism and the contribution of NPW to land surface water balance and its effects on crops in arid areas of Northwest China were reviewed. Finally, on the basis of combining the international frontiers, hot issues and development trends of NPW research, the shortcomings and problems of current NPW research are analyzed scientifically. It is pointed out that the study of NPW should focus on further revealing the complex formation mechanism of NPW on land surface, and strengthen the cognition of NPW in different climatic regions and different underlying surfaces. Breakthroughs have been made in key scientific issues such as the establishment of a specially targeted land surface NPW observation system, the development of the parameterization of land surface NPW in the numerical model, and the research and development of technical standards for the development and utilization of land surface NPW.
The TCIs (tourism climate indices) are applications of the human comfort in climate health tourism. TCIs aim to characterize the climate and environmental status of tourist destinations and provide a comprehensive measure of tourists’ climatic well-being. In this study, the Web of Science and China National Knowledge Infrastructure (CNKI) databases were searched for visualization analysis, explained the connotation of the TCIs and human comfort index, summarized the historical evolution of TCIs and the human comfort index, and discussed the existing problems and countermeasures of TCIs researches. In order to provide theoretical support for the in-depth research and sustainable development of TCIs in the future. The results are as follows: (1) The English studies were more concerned with tourism satisfaction and competitiveness, whereas the Chinese studies were more concerned with human comfort, climate comfort, and climate tourism. (2) Human comfort indices were primarily composed of meteorological factors and clothing insulation, which aims to reflect the human body's feeling of environmental comfort. The TCIs not only covers meteorological factors and aesthetic factors, but also considers health factors such as air quality and oxygen content, aiming to comprehensively evaluate the suitability of tourism activities and the effect of climate health of travelers.
