Abstract

The inhibitory effect of salt stress in rice is complex and is one of the main reasons for reduction of plant growth and crop productivity. In the present study, the response of rice callus cultivar Khao Dawk Mali 105 (KDML105), commonly known as Thai jasmine rice, to salt stress was examined. Callus cultures of KDML105 rice were exposed to salt stress by placing on Murashige and Skoog (MS) medium containing 250 mM NaCl. Growth, water content, proline and inorganic ion content in rice cells were measured during stress treatment for 8 - 10 days. After prolonged exposure to salt stress, growth and water content of rice cells were progressively decreased. Rice cells accumulated high level of Na⁺ during stress, whereas the accumulation of K⁺ and Ca²⁺ was decreased. High level of Na⁺ inside the cells inhibited the K⁺ uptake resulted in increase level of the Na⁺/K⁺ ratio. In addition, salt stress also caused an increase in the accumulation of proline. This result suggested that proline may play a crucial role in protecting the KDML105 rice cells under salt stress.

Key word: Aromatic rice, osmoprotectant, callus culture, salt stress.