XXIIIrd International Eucarpia symposium, Section Ornamentals ...

HEAT TOLERANCE IN PETUNIA AS
MEASURED BY AN ELECTROLYTE LEAKAGE
TECHNIQUE
Identification of heat-tolerant petunia (Petunia ×hybrida Hort. Vilm. Andr.) genotypes and
techniques for rapid assessment of heat-tolerant plants during breeding programs for
sub-tropical and tropical areas are desirable. The extent to which electrolyte leakage
from petunia leaf discs at 50 °C for 20 min, measured using a test for cell membrane
thermostability (CMT), could be related to the reduction in branch number induced by
heat in the greenhouse-grown plants were determined. Heat-intolerant cultivars exhibited
more reduced branches, but less reduced RI (relative injury) value than heat-tolerant
cultivars with increasing mean growing temperatures from 16 to 27 °C. The cultivars with
a high RI value are those with the lesser CMT and more reduction in branch number by
high temperature at 27 °C. The relationship between the RI value occurring in leaf tissue
discs of two seed-propagated cultivars and treatment temperature from 25 to 56 °C was
sigmoidal. The RI values at the approximate midpoint of the sigmoid response curve
occurred at 47 °C for ‘Primetime Carmine’ regardless of growing day/night temperatures,
and at 47 and 49 °C for ‘Tidal Wave Silver’ grown at 25/20 °C and 30/25 °C,
respectively. A high temperature at 30/25 °C resulted in reduced branch number in
‘Primetime Carmine’ but not in ‘Tidal Wave Silver’.
P54
Tzu-Hsuan Liu
Chia-Yang Lin
Der-Ming Yeh
Department of Horticulture,
National Taiwan University,
No. 1, Roosevelt Road
Section 4, Taipei, 106,
Taiwan
dmyeh@ntu.edu.tw
Session Posters 127