Table 2.
Morphological traits of wheat with respect to their growth stages, influenced by cold stress.
| # | Traits | Growth stage | *Low Temp. & Duration | Growth Conditions | Cold induced alterations compared to control | References |
|---|---|---|---|---|---|---|
| 1 | Germination and emergence | Initial seedling stage (Vegetative) | ≤ 2°C (>2 d) Control: 30°C | Controlled (Incubator) | Delayed emergence Poor vigor |
Jame and Cutforth, 2004 |
| 2 | Leaf initiation | Seedling growth (Vegetative) | ≤ 5°C (12 h to 1 d) Control: 20°C | Controlled (Phytotron) | Leaf initiation
Growth rate Biomass |
Leonardos et al., 2003 |
| 3 | Ground cover/stand establishment | Tillering (Vegetative) | ≤ 0°C (> 5 d) | Field (Frost spells) | Number of tillers
Uneven stand establishment Stem apex killed |
Whaley et al., 2004 |
| 4 | Peduncle development | Stem elongation (Veg.  Rep.) |
≤ 2 to −9°C (≥ 2 d consecutively) | Field (Frost spells) | Internode extension
Stunted peduncle extension Shoot biomass |
Whaley et al., 2004 |
| 5 | Flag leaf and head emergence | Jointing booting (Reproductive) |
≤ 0 to −2°C (24–60 h) Control: 8°C | Controlled andOpen-top Chambers | Delayed floret growth Leaf chlorosis and wilting Denatured spikelet |
Li et al., 2015; Zhang et al., 2019 |
| 6 | Flowering, Pollination | Anthesis (Reproductive) | ≤ −2 to −6°C (2–6 d) Control: 6°C | Controlled (Phytotron) | Floret abortion Anthers desiccation Flower shedding |
Ji et al., 2017 |
| 7 | Final grain development | Grain filling (Reproductive) | ≤ −2 to −6°C (2–6 d) Control: 6°C | Controlled (Phytotron) | Number of grains/spikes
Incomplete fruit setting 1,000-grain weight Grain Yield |
Ji et al., 2017 |
| 8 | Root growth and development | – | – | – | Surface area
Thickened primary root axis. Lateral branches Hydraulic conductance Nutrient uptake |
Siddique et al., 2000; Farooq et al., 2009 |
*
Temperature mentioned here is a minimum recorded field/phytotron temperature during certain growth phases [Here, indicates a decrease].