Reduced cellular cross-sectional area in the leaf elongation zone of wheatcauses a decrease in dry weight deposition under saline conditions

Expansion and dry weight (DW) of wheat leaves are spatially distributed alo ng the axis and affected by salinity. The objective of this study was to ev aluate the effect of salinity on the spatial distribution of cellular cross -sectional area and DW in the elongating and mature leaf zones of leaf 4 of the main stem of spring wheat (Triticum aestivum L. cv. Lona) during its l inear growth phase. Plants were grown in illitic-chloritic silt loam with 0 and 120 mM NaCl in a growth chamber. Cellular cross-sectional area and DW contents of leaves were determined on the 5-20-mm scale along the leaf axis . Spatial distribution of cellular cross-sectional area changed slightly wi th distance within the elongation zone in both treatments. The cellular cro ss-sectional area of the leaf at 120 mM NaCl was reduced by 32% at 5 mm, as compared with about 36% averaged from the region between 5 and 30 mm from the leaf base, indicating that the reduction in the cellular cross-sectiona l area by salinity occurred mainly at the leaf base when the leaf initiates . A slight decrease in the DW per leaf length at a given location in the el ongation zone may be due to the strongly decreased cellular cross-sectional area by salinity. This suggests that the limitation of leaf growth by sali nity may be due mainly to the effect of salinity on leaf expansion, but not due to the effect on the synthesis of dry matter.