Percent reduction (−) in Fv/Fm compared to zero values (i.e., before heat stress was imposed). Species are ranked in order of tolerance based on percent reductions in Fv/Fm as a measure of damage to the leaf photosynthetic system.
| Fv/Fm | ||
|---|---|---|
| Species | July | August |
| A. pseudoplatanus ‘Negenia’ | −18.2d | −7.3c |
| A. pseudoplatanus ‘Spaethii’ | −29.0c | −11.4c |
| A. platanoides ‘Royal Red’ | −33.6bc | −12.8c |
| A. campestre | −31.6bc | −13.9c |
| A. campestre ‘Louisa Red Shine’ | −34.4bc | −31.6b |
| A. platanoides ‘Princeton Gold’ | −36.0bc | −26.4b |
| A. platanoides ‘Emerald Queen’ | −40.8b | −32.0b |
| A. platanoides ‘Drummondii’ | −53.0a | −47.9a |
Numbers within a column followed by a common letter (taken from regression equations [Figure 1]) are not significantly different according to Tukey’s honest significance test (P = 0.05).