Ma. Morales et al., CHANGES IN THE GROWTH, LEAF WATER RELATIONS AND CELL ULTRASTRUCTURE IN ARGYRANTHEMUM-CORONOPIFOLIUM PLANTS UNDER SALINE CONDITIONS, Journal of plant physiology, 153(1-2), 1998, pp. 174-180
Pregerminated seeds of Argyranthemum coronopifolium grown in a hydropo
nic culture under growth chamber conditions were exposed to 70 mmol/L
NaCl nutrient solution 45 days after sowing. The saline treatment was
imposed for 15 days. Saline stress reduced the relative growth rate (R
GR), net assimilation rate (NAR) and leaf area ratio (LAR). Leaf water
potential (Psi(l)) and leaf osmotic potential (Psi(s)) decreased sign
ificantly in the treated plants while the leaf turgor potential (Psi(p
)) increased due to osmotic adjustment (decrease of the leaf osmotic p
otential at full turgor, Psi(os)). This osmotic adjustment was not suf
ficient to avoid decreases in stomatic conductance (g(l)) and net phot
osynthesis (P-n). The data obtained by X-ray microanalysis on individu
al cells from the epidermis, mesophyll and palisade showed that saline
stress led to a similar pattern of Na+ and Cl- accumulation and loss
of K+ in all leaf tissues. Salinity increased the number of lipid bodi
es in the cytoplasm and induced variations in che chloroplasts, whose
size increased significantly as did their content of starch grains. Th
ese alterations were common in mesophyll and palisade cells although m
ore noticeable in the latter. Transfer cells were observed in the leaf
. However, they did not confer salt-tolerance and some were seriously
damaged by the salt. The results showed that Argyranthemum coronopifol
ium although a wild native from littoral areas, is not a salt tolerant
species.