Characterization of Rice (Oryza sativa L.) Physiological Responses to α-Tocopherol, Glycine Betain or Salicylic Acid Application.

The α-tocopherol, glycine betaine (GB) and salicylic acid (SA) play important but different roles in inducing stress tolerance in many plant species. The potential impact of α-tocopherol, GB or SA on higher plants has been the subject of many studies, with special emphasis on oxidative stress tolerance under adverse conditions. However, little work has been carried out so far on rice (Oryza sativa L.) responses to α-tocopherol, GB or SA under optimal conditions. A study was conducted to determine the effects of α-tocopherol, GB or SA application on rice morphology, phenology and physiology under optimal conditions. Plants were treated with α-tocopherol (2.3 kg a.i. ha^-1), GB (2.0 kg a.i. ha^-1) or SA (12.9 g a.i. ha^-1), 20 days after emergence (DAE). The α-tocopherol, GB or SA application did not affect number of productive tillers per plant, days for 1^st panicle emergence, pollen germination and biomass production; however, plant height, leaf characteristics, leaf physiology, spikelet fertility, panicle and grain characteristics and grain yield of rice plants were affected. Plants treated with α-tocopherol, GB or SA showed 6%, 13% and 13.5% increase in grain yield per plant compare to untreated plants as a result of decreased respiration rates and increased membrane integrity and spikelet fertility.