European Journal of Sustainable Agroecosystems

Background: Chickpea (Cicer arietinum L.) is the second most significant cool-season leguminous food crop in the world but its reproductive phase is particularly vulnerable to the terminal heat stress phenomenon, which has become an increasing occurrence as short planting dates force the beginning of flowering and pod setting during warm months. A sudden rise in temperature is sufficient to eliminate pollination viability and cause the abandonment of the pods and flowers, resulting in a yield loss of 30% to 50%.
Objective: This paper compiles confirmed scientific research relating to pollen viability under terminal heat stress, the disruptions to the homeostasis of reactive oxygen species (ROS) in chickpea, and the consequent changes in hormonal signalling, identifying gaps in the research that prevent the practical application of the findings.
Sources of information: A systematic, PRISMA-guided search using Scopus, the Web of Science, PubMed, AGRIS and Google Scholar (2015-2026, but including selected major contributions from earlier than 2015) generated a total of 612 publications of which 58 were relevant to the study while 34 were utilized in the comparative table.
Heat stress consistently damages pollen germination and viability due to altered anther sucrose metabolism, peroxidation of membrane lipids due to excessive superoxide and hydrogen peroxide, and reduced ascorbate-glutathione cycling. Coincidentally with the rise in abscisic acid, there is a drop in the signaling of auxin, gibberellin, and cytokinin, with subsequent remodelling of ethylene and jasmonate signaling pathways amassing, which worsens the conditions in tapetum and pollen. Resistant genotypes constantly display higher levels of antioxidant enzymes, greater osmolyte levels, and more intense induction of the synthesis of heat shock proteins with lower decrease of pollen viability and pod setting. 
There are certain gaps in knowledge regarding mechanisms of ROS-hormone communication in chickpea anthers.
Conclusion: The combination of pollen phenomics, multi-omics profiling and genomics-led breeding based on heat-tolerance loci is the best avenue to achieve heat-resistant chickpea; it requires more coordination of physiological mechanisms and breeding practices than available at present.