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Cut flower chrysanthemum (Dendranthema grandiflora 'Jinba') plants were treated with 40 °C/35 °C or 33 °C/28 °C (day/night) for 11 days and then transferred to 23 °C/18 °C for 5 days to study the changes in their photosysnthesis and flourescence parameters under high temperature stress and normal temperature recovery. The results showed that on the 5th day of 33 °C/28 °C treatment, net photosynthesis (Pn) decreased gradually and stomatal conductance (Gs) decreased evidently; while after recovery for 5 days, both P n and G s resumed to 80% of the control. At 40 °C/35 °C, Pn and Gs decreased dramatically. The increase of intercellular CO2 concentration (Ci) at the early stage under given high temperatures that the photosynthesis inhibition by high temperature stress was resulted from non-stomatal limitations. However, 9 days later, stomatal limitation became the mainly cause of photosynthesis inhibition by high temperature stress was resulted from non-stomatal limitations. However, 9 days later, stomatal limitation became the mainly cause of photosynthesis inhibition. The intrinsic photochemical efficiency (Fv/Fm), quantum yields of PS II (Φ PS II), and the efficiency of excitation energy capture by open PS II reaction center (Fv'/Fm') at 33 °C/28 °C and 40 °C/35 °C all decreased light capture and efficiency of electron transfer through PS II. The photochemical quenching (qp) at 33 °C/28 °C descended first and turned to rise then, suggesting that the election transfer was firstly restrained by the stress. Contrastively, qp rose continuously at 40 °C/35 °C, indicating that oxygen-evolving complex (OEC) was the location in chrysanthemum photosynthesis apparatus most sensitive to extreme high temperature. [ABSTRACT FROM AUTHOR]

Based on the salt-tolerance identification of a series of cucumber rootstock varieties, the cucumber cultivar 'Xintaimici' grafted on different salt-tolerant rootstock varieties 'Sherpa', 'Shintosa' , 'Tielizhen' , and 'Figleaf gourd' was selected to study its seedlings physiological responses to NaCl stress, taking the self-rooted ones as the control. Under the stress of 100 mmol NaCl x L(-1), the leaf electrolyte leakage rate and malondialdehyde (MDA) content of the grafted seedlings were significantly lower than those of self-rooted seedlings, and the seedlings grafted on 'Figleaf gourd' showed the lowest electrolyte leakage rate and malondialdehyde (MDA) content, followed by the seedlings grafted on 'Tielizhen', 'Shintosa' , and 'Sherpa'. The leaf proline and soluble sugar contents and peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities of the grafted seedlings were significantly higher than those of the self-rooted seedlings, and the POD, SOD, CAT, and APX activities were the highest for the seedlings grafted on 'Figleaf gourd' and the lowest for the seedlings grafted on 'Sherpa', but had no significant differences for the seedlings grafted on 'Tielizhen' and 'Shintosa'. The leaf Na+ content of the seedlings grafted on different rootstock varieties ranked as 'Figleaf gourd' < 'Tielizhen' < 'Shintosa' < 'Sherpa', while the leaf K+ content had little difference for the seedlings grafted on 'Figleaf gourd', 'Tielizhen', and 'Shintosa' but was significantly higher than that for the seedlings grafted on 'Sherpa'. The self-rooted seedlings had the highest leaf Na+ content but the lowest leaf K+ content. The leaf Na+/K+ ratio of grafted seedlings was significantly lower than that of self-rooted ones, and the seedlings grafted on 'Figleaf gourd' had the lowest leaf Na+/K+ ratio.