Gc 16a

The MT content was determined in reference to the previously reported method (Qianqian et al., 2015 (link)), with some modifications. The sample weight was 3.0 g, and the MT was extracted with analytical grade methanol; the final extract was purified by the C₁₈ solid-phase extraction cartridge (ProElut^TM, DIKMA, China) with the help of a vacuum pump, and then the volume was adjusted to 1 mL. The ethylene production rate was measured by gas chromatography (Shimadzu GC-16A, Japan) and repeated three times (Farmer et al., 1986 (link)). In order to avoid the wounding effect on ethylene production, the wound was wrapped in cotton with water after sampling and then sealed with a sealing film. The leaves were immediately put into a container and sealed, maintained in a light incubator at 25°C for 24 h, and then the gas was extracted into a 1 mL syringe for determination. The extraction and determination of ACC were according to Tucker et al. (2010) (link). After O₃ treatment, the samples were stored in liquid nitrogen.

Gas chromatography (GC-16A, Shimadzu, Kyoto, Japan) was used to measure the ethylene production of ‘Xiaobai’ apricot fruit. A total of 500 g of apricot fruit was placed in a 1 L closed chamber for 1 h, and an injection needle absorbed 0.1 mL of gas. The following were the GC conditions: The column and detector temperatures were 50 °C and 150 °C, respectively. The nitrogen (N₂) flow rate was 18 mL min⁻¹. The ethylene production rate is expressed in ng kg⁻¹ s⁻¹ as the amount of ethylene produced by 1 kg fruit per unit time.
A sample of 1 kg of fruit was randomly selected and placed in a 1 L sealed tank attached to a carbon dioxide tester (CES-10, Zhonggu, Shanghai, China) for 30 min at 4 °C. Respiration rate was expressed by CO₂ production rate in ng kg⁻¹ s⁻¹.