Long-term high temperature stress decreases the photosynthetic capacity and induces irreversible damage in chrysanthemum seedlings

To study the effects of long-term and short-term high temperature stress recovery on physiological functions appearance quality chrysanthemums, a controlled experiment with chrysanthemums was conducted. The treatments were 25 °C for 3 days (T1D3), 9 (T1D9), 41 (T2D3) 41°C (T2D9). results indicated that there is no significant difference between T1D3 T1D9 groups. Conversely, total chlorophyll content (Chl), net photosynthetic rate (PN), maximum quantum yield Photosystem II (PSII) (FV/FM) under T2D3 T2D9 decreased by 27.07%, 43.30%, 5.62%, 44.85%, 68.22%, 8.29%, respectively. JIP-test showed T2D9-stressed plants had lower efficiency functional antenna size, higher activity reaction centre than T2D3. contents malondialdehyde, soluble protein proline increased 3.67 nmol/g FM, 298.75 μg/g, 192.99 antioxidant enzymes activities inhibited significantly T2D9. After relieved, Chl, PN, FV/FM recovered to same level as T1D3, while did not. Furthermore, diameter flowers in T1D3. However, poorly. Both anthocyanin reduced comparing T1D9, indicating damage chrysanthemum seedlings caused irreversible.