. 2021 Jul 8;12:676884. doi: 10.3389/fpls.2021.676884

Table 3.

Physiological and biochemical traits influenced by cold stress.

#	Processes	Effect	*^Low Temp. & Duration**	Growth conditions	Cold Induced alterations compared to control	References
1	Photosynthesis	Poor photosynthetic activity	≤ 5°C at vegetative phase (1 d) Control: 20°C ≤ 4°C at vegetative phase (1–7 d) Control: 22°C −2 to −6°C at reproductive phase (≥2 d) Control: 6°C	Controlled (Growth Chambers, Phytotrons)	Leaf Area $↓$ Leaf water content $↓$ Chlorophyll a,b synthesis $↓$ CO₂ Assimilation $↓$ Quantum efficiency of PSII $↓$ Stomatal conductance $↓$ Electron transport chain (ETR) $↓$ Enzymatic activity $↓$ Photo-inhibition Source-sink imbalance	Venzhik et al., 2011; Dahal et al., 2012; Liu L. et al., 2019
2	Respiration	Reduced respiration rate	4⁻12°C at initial vegetative phase (>12 h) Control: 22°C ≤ 5°C at vegetative phase (1 d) Control: 20°C −2 to −6°C at reproductive phase (≥2 d) Control: 6°C	Controlled (Incubator, Phytotrons)	Damaged mitochondrial structure Kinetics of energy flow $↓$ Gaseous exchange $↓$ Enzymatic activity $↓$ ATP production $↓$ Metabolism dysfunction Energy reserves $↓$	Dahal et al., 2012; Li et al., 2013
3	Nutrient relations	Decreased nutrient uptake and transport			Disturbed soil physio-chemical characteristics Disturbed microbial activity Reduced root surface area, thickened primary root axis and no lateral branching, Hydraulic conductivity $↓$ Imbalanced water relations leading drought & reduced phloem activity	Siddique et al., 2000; Farooq et al., 2009

Temperature mentioned here is the minimum recorded field/phytotron temperature during certain growth phases, while 20–25°C is the optimum temperature for efficient biochemical functioning Austin, 1990 [Here, $↓$ indicates a decrease].