The Effects of Water Deficit Stress on Physiological and Biochemical Changes of Medicinal Plants Ocimum basilicum L. under Climatic Conditions in Ardabil, Iran

ABSTRACT Basil (Ocimum basilicum L.) is an important medicinal and aromatic plant which is cultivated throughout the world and investigation the effects of important agronomic factors on its quantitative and qualitative yield are necessary.This research was conducted in the years 2013-2014 in agricultural farm of Mr. Abedini in the village Mahmoud Abad of Namin city functions, (Ardabil, Iran), as factorial experiment in a completely randomized block design by 3 replications. The experimental treatments were water deficit stress (D1=70, D2=140 and D3= 210 mm evaporation from pan class A) as category factors and three levels of nitrogen fertilizer in the form of urea (N1= 0, N2 = 50, N3 = 100 kg/ha).The results showed that the most ratio of the essential oils of basil obtained in the first and the second harvests (2.37% and 1.81%, respectively) in the treatment of without nitrogen fertilizer and the lowest ratio of the essential oils of basil was in the first and second harvests (1.43% and 1.69%, respectively) in the treatment of 100 kg/ha nitrogen fertilizer. Interactions of water deficit stress and nitrogen fertilizer on dry matter yield per unit area was significant at total of two harvests (total yield); and the highest dry matter yield was observed in treatments of D1= 70 mm evaporation and 100 kg/ha nitrogen fertilizer (1000.01 kg of dry matter per hectare), and the lowest ratio was achieved in treatments of D3=210 mm evaporation without the use of fertilizer (516.43 kg of dry matter per hectare). On the other hand the results indicated that interactions of water deficit stress and nitrogen fertilizer on essential oil yield per unit area was not significant at the first harvest, the second harvest and total yield. However, the highest essential oil yield was obtained at the first harvest, the second harvest and total yield, (9.08, 7.54 and 15.21 l/ha, respectively) in the treatments of D1=70 mm evaporation and nitrogen fertilizer of 100 kg/ ha as well as the lowest essential oil yield (5.01, 5.1 and 9.03 l/ha, respectively) in the treatments of D3=210 mm evaporation and failure to use of nitrogen fertilizer