SCREENING SWEET CHERRY SELECTIONS FOR DORMANT FLORAL BUD HARDINESS

In Dec. 1990, sweet cherry (Prunus avium L.) selections varied in flor al bud kill from 9% to 92 % following exposure to severe cold. In the following winter, the hardiness of two hardy and two tender selections was analyzed by differential thermal analysis (DTA) to screen selecti ons for hardiness. In a mild winter, when buds remained at their minim um hardiness level, the hardy selections consistently were >2C hardier than the tender selections. About one-half of that hardiness differen ce was associated with differences in tissue water content, the other half with unknown factors. Buds of the tender selections began to deve lop earlier and bloomed earlier than the hardy selections. DTA analysi s of floral bud populations separated selections that clearly differed in floral bud hardiness.