Effect of Drought Stress on Antioxidant Enzyme Activities and Root Yield of Sugar Beet (Beta vulgaris)

摘要

The growth and development of plants are severely restricted by a variety of environmental stresses. Therefore, in order to evaluate the response of antioxidant defense system of three sugar beet genotypes to drought stress and improving soil water content management, a field experiment was conducted in a randomized complete block design under split plot arrangement with four replications at the Research Site of Sugar Beet Seed Institute in Karaj, Iran during 2008 and 2009 growing seasons. Irrigation treatments arranged in main plots during growing seasons included: 80 mm (I : as control), 130 mm (I ) and 180 mm (I ) evaporation from A class 1 2 3 pan under surface irrigation method, 30 mm (I ), 80 mm (I ), 130 mm (I ) and 180 mm (I : as severe drought) 4 5 6 7 evaporation with 100% volume of water requirement under trickle irrigation (Tape) method, and 30 mm (I ) 8 evaporation with 75% volume of water requirement under trickle irrigation (Tape) method. Genotypes included: 7112 (G ), BP-Karaj (G ) and BP-Mashhad (G ) were in sub plots. Results of the study showed that drought 1 2 3 stress decreased root yield (RY). Plants under water deficit stress indicated a significant increase in catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities in leaves. There were significant differences among genotypes for antioxidant enzyme activity except RY trait. Also, irrigation × genotype interactions showed significant difference on CAT and GPX activities. There was a negative correlation between enzymes activities and RY. It means that with increasing in enzymatic activity decreased RY. The obtained results suggested that drought stress leads to production of reactive oxygen species (ROSs), which resulted in an increased membrane permeability, i.e. malondialdehyde (MDA) content and oxidative stress in the plants. Also, genotypes with higher levels of antioxidants showed higher resistance to drought stress.