The effect of plant growth regulators on recovery of wheat physiological and yield-related characteristics at booting stage following chilling stress

Chilling stress has a strong negative impact on the growth and development of winter wheat (Triticum aestivum L.). To investigate the recovery of physiological function and yield formation by plant growth regulators following chilling stress, we performed low-temperature phytotron experiments at the booting stage, and sprayed 6-benzylamino adenine (6-BA), salicylic acid (SA), brassinolide (BR) and abscisic acid (ABA) after chilling stress. Plant growth regulators significantly enhanced SPAD value and net photosynthetic rate (Pn) in flag leaves following chilling stress (p < 0.05). Compared with the control group sprayed with distilled water, stomatal conductance (Gs) and transpiration rate (Tr) increased, while intercellular carbon dioxide concentration (Ci) decreased. In addition, the concentration of malondialdehyde (MDA) was significantly decreased, and the activities of superoxide dismutase (SOD) and peroxidase (POD) were enhanced (p < 0.05). Plant growth regulators also increased the grain filling rate during the 14 days after anthesis, thereby increasing grain weight. The grain number per spike, 1000-kernel weight, and yield per plant after harvest were also significantly enhanced (p < 0.05). Thus, spraying plant growth regulators at the booting stage relieved the adverse effects on physiological activity in wheat flag leaves caused by chilling stress, and 6-BA and SA were particularly effective.