Combined application of Serine and Kinetin regulates leaf disc senescence in Spinacia oleracea L.

Investigation was carried out to know whether serine can delay senescence and if it has any additive effect when applied in combination with kinetin (Kn) to leaf discs of senescent spinach leaves. The selected concentrations of serine and kinetin were 5 mM and 0.38 mM respectively and experiment was conducted under either 8 mmol photon m⁻² s⁻¹ or in dark for 6 days. The amount of protein along with pigments declined with time in untreated leaf discs and serine alone and in combination with Kn inhibited the degradation by controlling protease activity in light and dark. Progress of leaf disc senescence was characterized by an increase in total free amino acids; the increment was much greater in dark than in light. Protein bound amino acid content was also declined in control. However, serine individually and in presence of Kn brought down the accumulation of free amino acids and helped to retain bound amino acids significantly. This study reveals additive effect of serine with kinetin in delaying leaf senescence.