Changes in the inorganic status and enzyme activities in senescent leaves of chickpea, Cicer arietinum L.

Abstract

The changes in the level of some inorganic constituents and the activities of some important enzyme systems in senescent leaves of chickpea (Cicer arietinum L.) have been studied. In senescent leaves, a marked decline in the potassium and phosphorus contents was evident which was accompanied by the accumulation of calcium, silicon, chloride and manganese. Leaf senescence was accompanied by a great increase in hydrolytic processes, as revealed by the increase in the activities of acid phosphatase, alkaline phosphatase, ATPase, inorganic pyrophosphatase and 3-phosphoglycerate phosphatase. The activities of nitrogen metabolism enzymes, namely nitrate reductase, nitrite reductase, glutamine synthetase and alanine aminotransferase, and of photorespiratory enzymes -- phosphoglycolate phosphatase, glycolate oxidase and catalase, were lower in senescent leaves. Leaf senescence was further associated with an increase in the activities of peroxidase and polyphenol oxidase, a considerable depression in pyruvate kinase activity, and a slight elevation in aldolase activity.