Extreme temperature damage – from DC60

Within the manual Protocols for experimental plot sampling, handling and processing of cereals in field experiments(external link) by G.J. Rebetzke (Greg.Rebetzke@csiro.au), A. van Herwaarden, B. Biddulph, C. Moeller, R. Richards, A. Rattey and K. Chenu.

Extreme temperature events may sometimes occur before, during or soon after anthesis. Factors including genotype, tiller age, and water availability can all contribute to differences in expression of frost damage and associated effects on grain number, size and yield. Hot, dry winds under drought can contribute death of the upper ear producing a -tipping’ phenotype.


Frost: Assessment of frost damage should wait until midway through grain-filling. This is because the damage and the timing of expression will vary with floret position on the ear (Fig. 21). Tertiary florets flower later and so may appear as frost-damaged.

High temperature: High temperature damage is best recorded at physiological maturity after the period for high temperatures is passed and symptoms readily expressed.

For both frost and high temperature damage:

1. Hold 10 random heads in your hand and estimate the percentage of spikelets missing grain. Record this estimate as:

1 = >90% grain missing; 2 = 80% grain missing; 3 = 70% grain missing; 4 = 60% grain missing; 5 = 50% grain missing; 6 = 40% grain missing; 7 = 30% grain missing; 8 = 20% grain missing; 9 = <10% grain missing

2. Repeat for all plots.

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Figure 21. The timing of frost will affect which florets are damaged and which florets survive to produce seed (left). Severe drought and frost commonly coincide to produce severe tipping damage (right)

Other resources

Appendix 1.(external link) Text description of phenological scale, Zadoks decimal code (DC).
Appendix 2.(external link) Picture description of phenological scale, Zadoks decimal code (DC).
Zadoks JC, Chang TT, Konzak CF (1974) A decimal code for the growth stages of cereals. Weed Research 14(6),415-421. doi: 10.1111/j.1365-3180.1974.tb01084.x

Notes and troubleshooting tips


Download complete manual: Protocols for cereal field experiments_Nov2012.pdf

Health, safety & hazardous waste disposal considerations


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