In the diameter of the vascular bundles of relatively tolerance
to salinity on growth parameters, Saule variety was
reduced greatly compared to other varieties(by31%) (Figure
6).
Reducing the vascular bundles diameter is directly
related to decreasing the area xylem vessels, which as
conductive elements are clearly responsible for holding
various elements by changing their diameter (Ortega et
al., 2006). It is supposed that reduction in the number of
conducting elements has been reported in literature as
being an adaptive measure for securing water flow (Baas
et al., 1983). Reduction in size and number of conducting
elements of the xylem in response to heavy metals was
reported by Sandalio et al. (2001).
Munns (2002) indicated that the reduction of leaf, sheath
thickness and stem area might be because Salinity reduces
the ability of plants to take up water and this causes
reduction in growth rate. If excessive amounts of salt enter
the plant they will eventually rise to toxic levels, transpiring
leaves and reducing the photosynthetic capacity of
the plant.