Osmolyte Accumulation of Armeniaca vulgaris under Continuous Drought Stress

In this paper,the osmotic regulation characteristics of 4 types of Armeniaca vulgaris seedlings under 80-day drought stress were studied. Drought stress treatment was applied to test the osmotic regulation characteristics of biennial seedlings of Armeniaca vulgaris f. aurantica L.,Wang et D. F. Cui and Armeniaca vulgaris f. glyeyosma L.,Wang et D. F. Cui,and the relative soil moisture content at depth of 15-20 cm,relative water content in leaves of A. vulgaris and the contents of Na+,K+,soluble protein,soluble sugar and proline were measured every 20 days. The results show that the relative soil moisture content at depth of 15-20 cm was decreased to slight drought stress (54%) after the seedlings were irrigated for 20 days,the relative water content in leaves was maintained higher than 80% except that in leaves of sweet kernel No.2. Under slight drought stress,K+ accumulation occurred in leaves of most wild apricots. Na+ accumulation occurred in leaves of all four types of wild apricot seedlings when the relative soil moisture content was decreased to the severe drought stress (47%-18%) after the seedlings were irrigated for 40-80 days. Soluble protein was relatively sensitive to drought stress,it was accumulated under slight to moderate drought stress,and such accumulation was possibly related to the drought-resistant capability of seedlings. Soluble sugar was also accumulated when drought stress was severer. Proline content was sharply increased under severe drought stress after the seedlings were irrigated for 60 days,but it was too low to contribute to osmotic regulation under hyperosmotic conditions,which suggests that the Proline accumulation is a symptom that the cells were injured under such drought stress.