Changes in Some Enzyme Activities during Excised Rice Leaf Senescence under NaCl — Stress

Abstract

Excised rice ( Oryza sativa L. cv. RAT-NIA) leaves were used to compare the changes in some enzyme activities during senescence in non-stressed and salt-stressed leaves. During the process of leaf senescence, chlorophyll and protein contents decreased which were accelerated and retarded by salt stress and kinetin respectively. Catalase activity exhibited a decreasing trend in non-stressed leaves which was retarded by salt stress and kinetin treatment further retarded the trend in both nonstressed leaves. Salt stress accelerated the increasing trend of peroxidase activity in senescing leaves which was further accelerated by kinetin, being pronounced more in salt-stressed leaves. The decreasing trend of alkaline inorganic pyrophosphatase was accelerated by salt stress and retarded by kinetin. These results suggest that salt stress does not accelerate all the enzymatic processes associated with leaf senescence.