DIFFERENTIAL FLOOD STRESS RESISTANCE OF 2 ALMOND CULTIVARS BASED ON SURVIVAL, GROWTH AND WATER RELATIONS AS STRESS INDICATORS

Potted almond trees (Amygdalus communis L.) of the two cvs Ramillete a nd Garrigues were submitted to two treatments: non-flooded (control) a nd flooded for 7 d in June 1991 under field conditions. After being su bmerged for one week, the almond trees were removed from the water (re covery period). The effects of flooding on the growth. stomatal behavi our, leaf water potential, osmotic potential and turgor potential were examined through the experimental period. Flooding caused a reduction in root dry weight of 'Ramillete', wilting, chlorosis and necrosis of the leaves, and plant death. Epinasty occurred in treated trees, but it appeared sooner in 'Garrigues' than in 'Ramillete'. Garrigues prese nted the lower resistance of plant plus soil (R((p+s))) for both treat ments. After the flooding period, a progressive reduction of R((p+s)) values was noted in 'Garrigues'. The decrease in leaf water potential by flooding in both cultivars can be related to an increase in the res istance to water uptake. Leaf osmotic and turgor potential behaviour c onfirm the progressive dehydration of leaf tissues. The continous decr ease in psi(l) psi(s) and psi(p) values in 'Ramillete' indicated that the severity of the damage induced by flooding stress was irreversible in this cultivar. The reduction in leaf conductance (g(l)) can be rel ated to the leaf water deficit by effects of flooding, the recovery of g(l) for 'Garrigues' occurred 20 d after leaf water potential. The di fferences between the cultivars suggest that they differ in their abil ity to withstand flood conditions and their association is not desirab le in poorly drained soils.