Changes in PSII Function during the Senescence of Flag Leavesin Super-High Yielding Hybrid Rice (Oryza sativa L.)

Abstract:

The changes in light energy dissipation and xanthophyll cycle components in super-high yielding rice (Oryza sativa L.) cv. Peiai 64S/E32 were compared with those in traditional hybrid Shanyou 63 during the senescence of flag leaves in the field. The results showed that the maximum photochemical efficiency of PSII (F_v/F_m), quantum efficiency of PSII (ΦPSII), photochemical quenching coefficient (qP) and photosynthetic rate all decreased with the senescence of flag leaves, but the non-photochemical quenching coefficient (NPQ), the pool size of xanthophyll cycle (Z+A+V) and deepoxidation state (DES) increased. There was no significant difference in ΦPSII and qP between super-high yielding rice Peiai 64S/E32 and traditional hybrid Shanyou 63 on the 55-75 day after transplanting, but the decreases in ΦPSII and qP in Peiai 64S/E32 were less than those in Shanyou 63 after transplanting for 75 days. This suggests that there is a better PSII function for utilization of the absorbed light energy in Peiai 645/E32 than in Shanyou 63 during the senescence of flag leaves.