Table 2.

Percent reduction (-) or increase (+) in leaf chlorophyll content (SPAD values) compared to zero values (i.e., before heat stress was imposed). Species are ranked in order of tolerance based on percent reductions in SPAD values as a measure of damage to the leaf chloroplast membrane.

A. pseudoplatanus ‘Spaethii’+2.46a–5.52a
A. campestre ‘Louisa Red Shine’–1.57a–3.90a
A. pseudoplatanus ‘Negenia’–2.25a–3.25a
A. platanoides ‘Royal Red’–3.94a–3.85a
A. campestre–6.36a–1.22a
A. platanoides ‘Emerald Queen’–4.70a–7.55a
A. platanoides ‘Princeton Gold’–5.31a–10.6a
A. platanoides ‘Drummondii’–8.82a–8.11a
  • Numbers within a column followed by a common letter (taken from regression equations [Figure 2]) are not significantly different according to Tukey’s honest significance test (P = 0.05).