Physiological significance of ascorbic acid in relation to drought resistance in rice (Oryza sativa L.)

Summary A pot-culture experiment was undertaken to assess the physiological significance of ascorbic acid in relation to drought resistance in two high-yielding varieties of rice — Taichung Native — 1 and I.R. 8. The soil-moisture stresses were maintained at 7–10 and 15–20 per cent moisture at field capacity. The wilting treatments were given only at tillering and shooting stages. Observations pertaining to survivality of rice plants and determinations of ascorbic acid, acorbigen and ascorbic acid utilization in fresh leaves were made. The two varieties of rice,i.e. Taichung Native-1 and I.R. 8 were not identical in their drought tolerance. Taichung Native-1 was more drought resistant which may be presumed in view of their differences in morphological make-up and demand for water at different stages of growth. The leaves of Taichung Native-1 showed greater contents of ascorbic acid and ascorbigen following increased rate of ascorbic acid utilization as compared to I.R. 8. These values were significantly reduced during shooting stage, a critical period to drought. This confirms the significance of ascorbic acid towards drought resistance in plants with special reference to rice.