Abiotic factors pose a significant constraint for food security and agricultural production worldwide, and the issue has been exacerbated by extreme and rapid climate change. Heat and drought are the most important limiting factors that have a significant influence on crop growth and production. For better management, it is critical to understand the biochemical, ecological and physiological responses to these stresses. Plant responses to these challenges may be divided into three categories: phonological, physiological and biochemical. This review gives a thorough description of plant adaptations towards drought and heat stress, with a particular emphasis on identifying similarities and variations. As a result of physical damage, biological disruption and biochemical abnormalities, suboptimal water supplies and unusual temperatures negatively impact crop development and yields. However, both of these stressors have a wide range of impacts and are thus complex to explain in terms of mechanics. More profound knowledge of how plants respond to various challenges can lead to more practical solutions and management. A distinctive aspect of the phenomenon is comparing fundamental behaviour with abiotic stresses.

Drought vs. climatic stress
Drought, excessive salinity and cold may all cause a cellular dehydration that manifests as symptoms of physiological dehydration. Drought stress occurs when soil and atmospheric humidity are low and the ambient air temperature is above normal. In this situation, the evapotranspiration flux is out of balance with the soil’s absorption of water (Suzuki et al., 2016). When the temperature of the soil and air rises over a certain threshold level for a certain period of time, it is referred to as heat stress. Temperature affects yields in a comprehensive multi-location research. Plant growth and agricultural yield of important crops are being adversely affected by these unfavourable circumstances, which cause the development of drought-prone regions (Suzuki et al., 2016; Ray et al., 2019). Both drought and heat must be evaluated together since their combined impact is greater than that of each of them alone. Numerous genes influence the body’s response to abiotic stress, such as heat or drought, whereas the underlying processes are more complicated than those for biotic stress, which tend to be characterized by monogenic resistance. Heat and drought responses may be complicated further by various environmental factors, both biotic and abiotic, which make research more difficult. Due to oxidative, osmotic and thermal stressors caused by water scarcity and soil salinity, these issues are indisputably important obstacles to production in agriculture (Barnabás et al., 2008). It has also been noted that the lower stomatal conductance and transpiration under these circumstances may cause heat stress when leaf temperatures increase. Growth and performance of plants deteriorate significantly in tropical and subtropical areas when there is a lack of water and high temperatures (Suzuki et al., 2016).