Research hotspots and frontiers analysis of heat stress in maize

As the world’s largest food crop, maize plays a vital role in maintaining global food security. However, global warming has led to frequent high temperature weather, which has severely limited the growth and yield of maize. Therefore, in-depth exploration of the research hotspots and frontiers in the field of global maize high temperature stress will help to cope with the challenges brought by climate change and promote the sustainable development of the maize industry. In this paper, CiteSpace software was used to analyze the annual number of the keyword co-occurrence, clustering and brust of 4255 papers related to high temperature stress of maize included in the Web of Science core database from 1990 to 2023. The results showed that the research hotpots mainly focuses on four aspects: growth and yield changes, physiological response, molecular mechanism and coping strategies of maize under high temperature stress. Through in-depth exploration of the research progress of these four aspects, it was found that high temperature stress at different growth stages caused different degrees of damage to maize, and the yield reduction range from high to low was flowering stage>filling stage>heading stage>seedling stage. High temperature stress can also cause changes in multiple physiological and biochemical characteristics of maize, including impaired photosynthesis, increased biofilm permeability, excessive accumulation of reactive oxygen species, and hormone imbalance. The molecular mechanism of maize in response to high temperature stress focuses on gene expression and heat shock protein operation, but the specific heat tolerance mechanism is still unclear. Through the comprehensive application of agronomic measures and breeding techniques, including sowing date adjustment, scientific water and fertilizer management, rational application of growth regulators and cultivation of heat-tolerant varieties, high temperature stress can be effectively alleviated and high and stable yield of maize can be promoted. In addition, the transcriptional regulation mechanism of maize in response to high temperature stress is the current research frontier and will also be a hot topic in future research. This paper comprehensively reviewed the literature on high temperature stress in maize in the past 34 years, which provided a useful reference for the study of high temperature resistance of maize and the formulation of mitigation measures.