International Journal of Plant & Soil Science

Five citrus proevancnes were subjected to watering levels in the nursery. The effects of watering regime were evaluated on the growth, physiological and biochemical attributes while the measured variables were deployed to rank tolerance to soil moisture deficits by citrus species. The watering regimes were 100 % field capacity (1.2 litres at four days interval), moderately watered: 75% field capacity (0.9 litres at four days interval) and 50% field capacity (0.6 litres at four days interval) which imposed at 16 weeks after transplanting. Data were collected on height and leaf development, root and shoot biomass, chlorophyll content, stomata architecture, proline, membrane lipid peroxidation and antioxidant enzymes (Superoxide dismutase (SOD), Catalase (CAT), Gluthathione (GSH). Citrus provenances differed in growth traits, stomata architecture, proline, membrane lipid peroxidation and and enzymatic activities. Watering regime induced significant changes in leaf chlorophyll and phenolic contents and enzymatic activities of catalase (CAT), superoxide dismutase (SOD), membrane lipid peroxidation (malonaldehyde (MDA) and Guaiacol peroxidase (GPx) in citrus. The 75 and 50% FC watering significantly enhanced MDA and proline and activities of enzymatic antioxidant in citrus seedlings compare with 100% FC watering. Activities of CAT and GPx were enhanced by 75% FC while CAT, SOD and GPx were enhanced by 50 % FC watering. Under water limitations, 75% FC watering can support citrus seedling growth and 50% FC for lemon under soil moisture limitation.