R. Save et al., WATER RELATIONS, HORMONAL LEVEL, AND SPECTRAL REFLECTANCE OF GERBERA-JAMESONII BOLUS SUBJECTED TO CHILLING STRESS, Journal of the American Society for Horticultural Science, 120(3), 1995, pp. 515-519
One-gear-old gerbera plants subjected to 1 night at 5C had reduced lea
f water losses and chlorophyll content and increased root hydraulic re
sistance, but stomatal conductance and leaf water potential did not ch
ange. After 3 nights,leaf water potential had decreased and leaf refle
ctance in the visible and the near-infrared had increased. Similarly,
abscisic acid (ABA) in leaves had increased and cytokinins (CK) in lea
ves and roots had decreased, but ABA levels in roots did not change. A
fter 4 days at 20C, root hydraulic resistance, reflectance and leaf wa
ter loss returned to their initial values, but leaf water potential an
d chlorophyll content remained lower. Leaf ABA levels reached values l
ower than the initial, while root ABA and leaf CK levels retained the
initial values. These data suggest that in the gerbera plants studied,
3 nights at 5C produced a reversible strain but otherwise plants rema
ined uninjured, so this gerbera variety could be cultured with low ene
rgetic inputs under Mediterranean conditions. The results mag indicate
that ABA and CK were acting as synergistic signals of the chilling st
ress. Spectral reflectance signals seemed to be useful as plant chilli
ng injury indicators at ground level.