Effect of low temperature stress on the cold-resistance physiological indexes of 10 germplasm resources of Roegneria in Qinghai

In order to study the effect of low temperature on the physiological indexes of 10 populations of six wild species belonging to the Roegneria genus in the Three Rivers region of Qinghai, seedlings with four to five leaf stages were used as experimental materials, and the leaf chlorophyll (Chl), soluble sugar (SS), malondialdehyde (MDA) , free proline (Pro) , catalase (CAT) and peroxidase (POD) activities, and cell membrane permeability were measured under low temperature stress of between -25 and 5 ℃. The results showed that the cold resistance indexes of plant materials, such as Chl content, MDA, SS content, Pro content, and CAT and POD activity were significantly different under low temperature stress compared to the control. Different materials have different change ranges, and present different change rules, that is electrolyte permeability continues increasing by increasing the size of the S curve. The MDA content of the all experimental materials tended to remain consistent first increase, and then decrease. The contents of SS and Pro presented as an inverted V-shape, increasing first and then decreasing. The Chl content of nine materials continued to decrease. Membership function analysis showed the order of cold resistance of the 10 Roegneria germplasms is: Roegneria yushuensis (Maduo) > R. yushuensis (Tiebujia) > R. yushuensis (Xinhai) > R. stricta (Tongren) > R. abolinii var. divaricans(Huangyuan) > R. abolinii var. divaricans (Zeku) > R. brevipes (Qumalai) > R. purpurascens (Maixiu ) > R. brevipes (Zeku) > R. trichospicula (Zeku), in order from the strongest to weakest.