Table 2.

Impact of heat stress on different traits/biological processes of wheat.

Trait/ Biological Process	Responses/Consequences/Impact	References
Morpho-phenological behavior	Poor germination and seedling establishment	[34,40]
	Reduction in root length, shoot growth and dry matter	[34,41]
	Reduction in effective tiller	[42]
	Reduced ear length, number of spikelet and fertile floret	[43,44]
	Abortion of flower and fruits	[11,12,41]
	Shedding of leaves	[45,46]
	Reduction in phenological duration of crop	[14,47]
	Reduced days to germination, anthesis and maturity	[14,43]
	Reduction in germination of pollen grains and spikelet fertility	[11,12,48,49]
	Reduced grain filling period	[11,14,43,45]
Grain development and quality	Reduction in number or size of grain	[11,14,19]
	Reduction in harvesting index	[48]
	Increases rate of grain filling but shortened grain filling duration	[50]
	Reduction in transportation of photo-assimilates to grain	[51]
	Increase in grain protein and reduction in quality of proteins	[52]
	Reduced starch synthesis	[51,52]
	Reduced total soluble sugar and super molecules	[51,53]
	Reduction in essential amino acids	[50]
	Reduced bread making quality	[52]
	Reduction in flour quality and sedimentation index	[50,54]
	Reduction in economic grain yield	[51,55]
Physiological and growth behavior	Reduced photosynthesis and photosynthetic efficiency	[14,18,19,56,57]
	Increase in respiration and photorespiration at mild heat stress	[56,57]
	Increase in leaf senescence and reduction of chlorophyll content	[14,18,19,39,46]
	Reduction in the relative water content and leaf water potential	[45,58]
	Increased transpiration and decreased stomatal conductance	[59]
	Decrease uptake and translocation of water	[50,60]
	Increased canopy temperature	[61]
	Reduction in uptake, assimilation, and translocation of nutrient	[62,63]
	Reduction in specific leaf weight, leaf width and total dry matter	[38,64]
Molecular responses	Enhanced production of reactive oxygen species (ROS)	[18,19,65,66]
	Higher accumulation of osmolytes	[36,65]
	Destruction of plasma, mitochondrial and chloroplast membrane	[34]
	Reduction in Rubisco activity	[66]
	Reduction in soluble and rubisco binding proteins	[16]
	Denaturation and aggregation of seed proteins	[67]
	Higher accumulation of heat shock proteins	[68,69]
	Activation of antioxidant system and associated molecules	[70,71]