The participation of the antioxidant system in the drought tolerance of wheat
cultivars (Triticum aestivum L.) was studied under field
and in vitro conditions. Under field conditions, drought
tolerance was evaluated by the capacity to maintain the grain yield under
drought, which was higher in cvv. Elite and La Paz than in the sensitive cvv.
Oasis and Cruz Alta. Tolerant cultivars showed lower relative water content
(RWC) and lower above-ground vegetative biomass than sensitive cultivars.
Field assays did not show a clear correlation between water-stress tolerance
and antioxidant system behaviour. However, when leaves of cvv. with
contrasting drought tolerance were subjected to osmotic stress
in vitro, clear differences in the antioxidant system
activity and oxidative damage between cvv. were observed. In the tolerant
cultivar Elite, it was possible to observe an increase in ascorbate peroxidase
(APX), superoxide dismutase (SOD) and glutathione reductase (GR) activities, a
higher glutathione (GSH) and ascorbate content and less oxidative damage than
in the sensitive cultivar Oasis, which showed no changes or only slight
decreases in the enzyme activities. These results indicate that water stress
tolerance is in part associated with the antioxidant system activity, and
suggest that the behaviour of the antioxidant
systemin vitro assays can be used as an early selection
tool.
Developmental changes in collenchyma cell-wall polysaccharides in celery (Apium graveolens L.) petioles