Effect of water deficit and its interaction with ascorbate on proline, soluble sugars, catalase and glutathione peroxidase amounts in Nigella sativa L

In this research, proline, soluble sugars, catalase and glutathione peroxidase levels which change in response to water deficiency and the effect of ascorbic acid as protecting factor in Nigella sativa L. were surveyed. Plants were cultured in greenhouse and irrigated based on the following treatments: 1) Control with irrigation equal to field capacity, 2) two third of field capacity, 3) one third of field capacity, 4) two third of field capacity along with 10 mM ascorbic acid, 5) two third of field capacity along with 1 mM ascorbic acid, 6) one third of field capacity along with 10 mM ascorbic acid, 7) one third of field capacity along with 1 mM ascorbic acid. Proline and soluble sugars levels in shoots and roots were significantly different for all treatments except for the treatment with 2/3 field capacity along with 10 mM ascorbic acid. Enzymes levels in 1/3 and 2/3 treatments were significantly different in both shoots and roots. One mM ascorbic acid along with different field capacity showed no reducing effect. However, 10 mM ascorbic acid especially in 2/3 field capacity could reduce the effect of water deficit through reduction in level of metabolites produced in response to low irrigation.