Calcium regulates Gladiolus flower senescence by influencing antioxidative enzymes activity

The objective of the present investigation was to study the role of calcium on antioxidative enzymes activity during the post-harvest life of Gladiolus (Gladiolus grandiflorus). Among the various calcium (Ca) treatments, 50 mmol l(-1) Ca treatments caused the highest increase in the vase life of the spike, from 5.5 days in control to about 9 days. Relative water content and membrane stability index (MSI) decreased from I to V stage. However, significant increase in relative water content and MSI were observed by 50 mmol l(-1) Ca as compared to control. Indices of oxidative stress such as lipid peroxidation and lipoxygenase activity increased from I to V stage, but decreased significantly in 50 mmol l(-1) Ca treatment. The activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) decreased initially from stage I to II, followed by an increase in stage III and thereafter started to decline at stages IV and V. Ascorbate peroxidase (APX) activity increased initially from stage I to III and thereafter declined in stage IV and V in both control and treatment. However, Ca with concentration of 50 mmol l(-1) increased the activities of SOD, CAT and APX at all the stages. The results revealed that spikes treated with Ca (50 mmol l(-1)) solution maintained higher level of antioxidant enzymes activity and also showed delayed senescence in comparison to control.