Predicted number of heat units required to reach a given budbreak percentage on the terminal 30 cm (12 in.) of stems of selected red maple cultivars, 1999-2000.
Cultivar | Hours chilled | Initial budbreak | 10% budbreak | 25% budbreak |
---|---|---|---|---|
Predicted number of heat unitsz | ||||
‘Autumn Fantasy’ | 200 | 1,716y | 2,085 | 2,487 |
400 | 1,245 | 1,615 | 2,017 | |
600 | 843 | 1,212 | 1,614 | |
800 | 509 | 878 | 1,280 | |
1,000 | 243 | 612 | 1,015 | |
1,200 | 46 | 415 | 817 | |
r2 = 0.63 | ||||
October Glory® | 200 | 1784 | 1850 | 1948 |
400 | 1,348 | 1,414 | 1,513 | |
600 | 970 | 1,035 | 1,134 | |
800 | 648 | 713 | 812 | |
1,000 | 382 | 448 | 47 | |
1,200 | 174 | 240 | 338 | |
r2 = 0.50 | ||||
‘Franksred’ (Red Sunset®) | 200 | 1,728 | 2,052 | 2,419 |
400 | 1,207 | 1,531 | 1,899 | |
600 | 782 | 1,106 | 1,474 | |
800 | 453 | 777 | 1,144 | |
1,000 | 219 | 543 | 910 | |
1,200 | 80 | 404 | 771 | |
r2 = 0.66 |