Effects of complex salt-alkali stresses on seed germination of oat

In order to explore the effects of complex salt-alkali stresses on seed germination of Oat (Avena sativa), six alkali concentration treatments with six levels of salinity each, and in total 36 kinds of salt-alkali conditions were simulated by mixing neutral salts (NaCl and Na2SO4) and alkaline salts (NaHCO3 and Na2CO3) in various proportions. Germination percentage, germination energy, radicle and shoot length were measured. The results showed that, germination percentage and germination energy both decreased with increasing salinity under all alkali treatments, and the salinity inhibit effects increased as alkali concentration increased. When subjected to the highest salinity (144 mmol·L-1), germination percentage was 25.6%, 11.1%, 0, 0, 0 and 0, respectively, as alkaline salts proportion increased from 0 to 100%. Radicle and shoot length had the similar downtrends with germination index, and radicle growth was more sensitive to salinity stress. Stepwise regression analysis showed that, salinity was the dominant stress factor affecting seed germination. This may attribute to osmotic stress which mainly determined by sodium concentration in present study.