Abstract: The frequent occurrence of hailstorm in Xinjiang affects cotton (Gossypium hirsutum L.) production and causes enormous economic loss.  The indeterminate growth habit of cotton allows for varying degrees of recovery and yield when different hail damage levels occur at different stages, which brings inconvenience to agricultural insurance claims and post-damage management.  Therefore, this study aimed to elucidate cotton recovery and yield responses to different levels of simulated hail damage at different growth stages.  Four levels of hail damage (0, 30, 60, and 90%) were simulated every 15 d from the five-leaf stage to the boll opening stage in 2018 and 2019, for a total of six times (I, II, III, IV, V, and VI).  The results showed that seed cotton yield decreased as the damage level increased and yield reduction increased when the damage was applied to older plants (for 30, 60 and 90% damage levels, yield reduction was 9–17%, 22–37% and 48–71%, respectively).  One possible reason was that the leaf area index and leaf area duration of plant canopy decreased after hail damage, resulting in a reduction in the accumulation of above-ground biomass.  However, when hail damage occurred before bloom, due to the indeterminate growth habit of cotton, the vegetative organs produced a strong compensation ability that promoted the bud development.  The compensation ability of vegetative organs decreased when hail damage occurred after bloom and the recovery time was too short to promote new boll maturity.  As the first study to understand the recovery of cotton after hail damage, it analyzed the leaf area index, leaf area duration, above-ground biomass accumulation and yield, rather than the yield alone.  The findings are of great importance for cotton production as they inform decisions about post-damage management practices, yield forecasts and insurance compensation.

Key words: cotton , compensation , growth , simulated hail damage , yield