Most of the soils, which are develo

Most of the soils, which are developed
from Miocene lime marl, have clay-loam to clay textures
and a low organic matter content. Such soils frequently have
poor drainage and heavy rain or excessive irrigation causes
them to become waterlogged; air space is displaced by the
water and O2 in the soil is quickly depleted, which induces a
water stress situation in plants (Kawase 1981). Research into
the effects of water deficit on agricultural crops has been
extensive, whereas less attention has been focused on plant
responses to soil flooding.
The physiological responses to flooding represent a wide
range of metabolic, hormonal, developmental and physiological
processes. Among these, may be mentioned ethylene
accumulation, stomatal closure, wilting, changes in the leaf
insertion angle, reduced growth, and adventitious root formation
(Bradford and Yang 1981, Kramer 1983, Fitter and Hay
1987).
In fruit trees, the resistance to oxygen deficiency in roots is
mediated by the characteristics of the rootstock. Differences
in the level of soil aeration tolerated by the more commonly
used rootstocks of apricot trees have been described (Egea
1970, Crossa-Raynaud and Audergon 1987). Although Egea
(2000) indicated that Pollizo prune rootstock tolerates soil
flooding better than Real Fino apricot, there have been no
studies concerning the response of these apricot rootstocks
to different soil flooding treatments.
For these reasons, the aim of the present paper was to
study the effects of soil flooding on the plant-water relations
and vegetative growth of young apricot plants grafted onto
apricot and prune rootstocks, as well as to evaluate the effect
of rootstock on the degree of resistance of apricot plants to
flooding conditions.