Hailstorms are typically localized events in crop production (Bosco et al. 2018). Corp suffer from hail damage mainly embodied in defoliation timing and severity, and lead to reductions in crop plants and loss of photosynthetic organs (Battaglia et al. 2019). Besides the loss of photosynthetic area, hailstones also bruise the stalks of larger plants, resulting in interference with the movement of assimilates, include plant hormone, nutrients and water, ultimately affect the growth and development of plants (Battaglia et al. 2019).
The dormant bud in plant is the key factor to influence the recover efficiency and to decision the yield production. The degree of hail damages depends on hailstone size, intensity and the kinetic energy (Saa et al. 2011; Yue et al. 2019). Meanwhile, the growth stage and the elasticity of the crops also important to the extent of the hailstorm damage (Petoumenou et al. 2019; Yue et al. 2019). The damage is earlier, the loss degree is heavier, and in contrast, the risk is relatively low during the maturation stage of crop (Zhao et al. 2010), and our study proved that hailstorms during the budding stage may not result in significant cotton yield reductions than the seedling stage. The cotton plants with cotyledon and apical meristem during cotyledon period are easily destroyed because the slow growth and worse in resistance after hail storm (Wan et al. 2004). In this study, we performed several appropriate, experimentally sound investigations on damage plants of upland cotton in Handan and Cangzhou City in Hebei, China. Although a terrible hailstorm occurrence during early development stage, cotton plants have latent buds after damage. So, we can avoid to re-farm again or other crops and strengthen the field managements immediately to recover cotton plants. After fertilizing, intertill and prune in time, we adjusted the plant architecture to avoid the over flourishing growth. In addition, strengthening the root system underground was critical to promote the development of dormant buds. Similar management measures were also performed to recover plant growth after hail disaster to minimize the loss to crops in other studies (Hu 2008; Bal et al. 2017).
The unfruitful buds, bolls and damage ratios differed among different varieties after hail damage (Yang et al. 2004). In present study, different accessions showed varied recovery ability for yield production. Among them, the yield loss of 11–0514 and 11-7027 showed less than 20% of damage rate, similar results in the RIL and BC populations. However, yield production of Sumian 20, 11–0710 and 11–0516 increased after recovery, this phenomenon may be attributed to the earlier maturation period and the more effective bolls. In 2015E2, another research also concluded that although cotton plants sowing at the early period experiencing hail damage, they displayed better yield performance than the upland cotton plants re-sowing at the late period, and the rate of boll forming and opening was significantly affected by different varieties (Wang 2016). However, there was no significant effect on fiber length, fiber strength, fiber uniformity and fiber elongation in different cotton varieties (Wang 2016). Similar results also found here, four fiber quality traits increased slightly in different materials.
It is worth noting that although we reduced the loss by strengthen managements after hail storm, the development period of cotton plants was delayed. It is necessary to spray ethephon to promote early-maturing of bolls at mature. In fact, the hail disaster can be prevented and limited by early warning by weather forecast, as well as planting trees on a large scale (Yan 2016). In addition, artificial hail prevention system had been constructed and destroyed the hail formation manually in Xinjiang Autonomous Region in China (Institute of Cotton Research of CAAS 2013). Moreover, if the fertility of soil is good, no or less post-disaster recovery treatment measures can be taken except for timely intertill, so that the cotton can recover naturally (Wang 2016). Otherwise, further exploring the suitable measures were taken to recovery the cotton development status by applying different nitrogen fertilizers, regulator dosages and application times, to guarantee no significant impact on cotton yield after hail damage.