| To explore whether drought could induce oat’s (Avena nuda L.) cross adaptation to low temperature, Dingyou No. 6 seedlings were pretreated with drought condition, simulated by 20% polyethylene glycol 6000 (PEG) for 3 d. After recovering for 2 days, both pretreated and control were treated under low temperature (day/night temperature is 8℃/5℃). 14 physiological indexes of the seedling leaves were determined, including superoxide anion (O[XZ(180#][XZ)][KG-*3/5]2), H2O2, malondialdehyde (MDA), ascorbic acid (ASA), Glutathione (GSH), Soluble sugar (SS), Soluble protein (SP), Amino acid (AA), and proline (Pro) contents, relative water content (RWC) and superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) activities at 0, 1, 3, 5, 7 days after low temperature treatment, as well as the plant height increment and biomass increment of oat seedlings 7 days after low temperature stress. Principal component analysis and membership function analysis were used to evaluate the drought and low temperature resistance of oat seedlings. Results showed that compared with the control, drought pretreatment significantly enhanced the plant height increment and biomass increment of oat seedlings under low temperature stress, 14 physiological index values of oat seedling leaves, such as O[XZ(180#][XZ)][KG-*3/5]2, H2O2 and so on have also changed in different degree. The correlation analysis of 14 physiological index values after converting standardized deviation showed that there was a significant correlation between different variables. The principal component analysis with 5 principal component factors showed taht the variance contribution rate were 38.881%, 18.219%, 11.238%, 9.616% and 8.809% respectively. The cumulative variance contribution rate was 86.763%. For the primary group of principal components, SS, AA, Pro, O[XZ(180#][XZ)][KG-*3/5]2, H2O2, RWC, SOD and APX were the major contributors, while for the secondary group of principal components, POD, MDA and GSH were the major contributors, for the third group of principal components, CAT and GSH were the major contributors, for the fourth group of principal components, SP and Pro were the major contributors, for the fifth group of principal components，APX and ASA were the major contributors. 5 principal component score values in the subordinate function analysis showed that the comprehensive evaluation values of drought pretreatment were significantly higher than control during almost the whole low temperature treatment except the first day. In conclusion, drought could induce the cross adaptation to low temperature in oat seedlings. |