Abstract: A field experiment was carried out in typical saline-alkali soils to examine the effects of salt stress on root growth, antioxidant enzyme activity, respiration metabolism at different growth stages and yield of oats of salt-tolerant cultivar “Bai 2” and salt-sensitive cultivar “Bai 5”. The results showed that under salt stress, total root respiration rate of Bai 2 and Bai 5 decreased first and then increased across the growth period. The respiratory rate of EMP pathway in Bai 5 was higher than that in Bai 2, and increased by 83.3%, 120.3%, 3.3% and 63.9% in tillering, jointing, heading and filling stage, respectively. TCA pathway respiration rate of Bai 2 was significantly increased by 88.9% compared with Bai 5 at heading stage, while PPP pathway respiration rate of Bai 2 was significantly increased by 48.1% compared with Bai 5 at tillering stage. SOD enzyme activity of Bai 2 was significantly higher than that of Bai 5 at the tillering stage, jointing stage and heading stage, being 2.2, 1.5 and 1.6 times, respectively. SOD enzyme activity of Bai 5 was significantly increased by 1.8 times compared with Bai 2 at the filling stage. POD enzyme activity showed a similar pattern of SOD. The dry weight, total root length, surface area, volume, and average diameter of Bai 2 were higher than those of Bai 5 at different growth stages. Under salt stress, the number of harvested ears of Bai 2 was significantly increased by 96.6% compared with Bai 5, the number of grains per ear was significantly increased by 21.6%, 1000grain weight was significantly increased by 9.6%, and grain yield was increased by 24.7% (P<0.05). In summary, the transformation of EMP-TCA pathway to PPP pathway of Bai 2 in the early stage of growth enhances its adaptability to salt stress. Compared with Bai 2, all the examined parameters of Bai 5 were much lower, resulting in lower yield.

Key words: oat, salt stress, respiratory metabolism, antioxidant enzyme, yield.