Biochemical Characterization on Photosynthetic Activities during Dark Incubated Senescence of Wheat Primary Leaves by Gibberellic Acid

In annual crop plants like maize, rice and wheat etc. Senescence limits crop yields of annual crops like maize rice and wheat. Delayed leaf senescence is a desirable agronomic trait to improve crop yield. In this study 10 µM GA reduced the loss of wheat primary leaves under incubated dark conditions. GA reduced the loss of pigments, proteins, electron transport activities, spectral properties. The restoration of WCE activity by GA was closely associated with the restoration of PS II activity compared to that of PS I. GA treated leaf thylakoid membranes showed an increase in absorption at 680 nm moderate increase at 480 nm and 440 nm at 72 h during dark incubation. GA protected the degradation of water oxidation complex polypeptides (33, 23, 17 KDa) of PS II and slightly protected the PS I polypeptides.