| The relationship between changes of osmotica content and osmotic adjustment ability of wheat seedlings under drought and cold cross-stress and cross-adaptation was studied with sand culture in artificial illumination incubator.The result showed that the content of soluble sugar,proline,amino acid and soluble protein increased in the seedlings of the 3 wheat varieties under one stress(drought or cold),and the wheat varieties showed certain ability of osmotic adjustment.Under drought and cold cross-stress(drought + cold or cold + drought),the osmotica content and osmotic adjustment ability increased obviously(the ability of osmotic adjustment increased by 66.38% and 51.27% in Jinmai47,by 71.77% and 71.09% in Zhengyin No.1,and by 56.36% and 62.91% in Changwu 6878).The relative permeability of plasma membrane reduced as compared with one stress,drought or cold(the relative permeability of plasma membrane reduced by 23.03% and 22.94% in Jinmai47,by 20.27% and 8.91% in Zhengyin No.1,and 28.17% and 23.44% in Changwu6878).The result also showed that the ability of osmotic adjustment of resistant varieties was notably higher than susceptive varieties.When wheat was treated with cross adaptation for drought and cold,the pretreatment of one stress could increase resistance to another stress.It also showed that there was some common physiological metabolism under different stress,and enhancement of osmotic adjustment ability was one of the possible physiological metabolisms of cross adaptation under drought and cold cross-stress(drought + cold or cold + drought). |