Leaf area development of field-grown sunflower plants (Helianthus annuus L.) irrigated with saline water

Leaf area development and stomatal resistance of lield-grown sunflower plants (hybrid Mimosa) were studied in response to irrigation with saline water. Salt treated plants were irrigated with 1olo commercial sea-salt water solution. Irrigation started on the 3oth day after sowing when plants had l0 primordia ald 2 fully expanded basa.l leaves. Midday leal water potential decreased during the season in both sa-lttreated [I1) and control plants (I0), with lowerva.lues for Il. At anthesis, 65 days after sowing, the difference was 0.12 MPa and LAI of I0 was 3.3I whereas for I1 it was 2Oo/o lower. Il plants showed a remarkable morphologica-l adjustment to salt stress, by modulating leaf area through leaf expansion rate, whereas the role of leaI senescence was negligible. There was no physiological adjustment in terms of stomata-l resistance. In conclusion, I)eld-grown salt-treated sunflower plants showed avoidance mechanisms which are similar to those observed elsewhere in water stress conditions.