Abstract
Leaf development of wheat largely determines the rate of plant growth in the early growth stages and is most sensitive to salinity. The objectives were to investigate the shoot growth, area of leaves, and kinetics of leaf elongation of wheat seedlings (Triticum aestivum L.) grown in illitic‐chloritic silt loam with four salinity levels from 0 to 120 mM NaCl in growth chambers. Shoot fresh mass (FM) and leaf area were measured at days 12 and 18 after sowing. Instantaneous measurements of the leaf elongation rate (LER) of leaves 3, 4, and 5 of the main stem were carried out by using linear variable differential transducers (LVDT). Spatial distribution of relative elemental growth rate (REGR) and the length of the leaf elongation zone were determined by measuring displacement rates with a pricking method. Shoot FM per plant linearly decreased with increasing salinity levels. Leaf area under saline conditions was significantly correlated to the shoot FM during vegetative stages, indicating that leaf growth most sensitively responds to salinity. Salinity delayed leaf emergence and affected leaf growth longitudinally and laterally. Reduction in the final length of leaves 3, 4, and 5 was mainly a result of a decrease in their LER. The decreased LER under saline conditions was more pronounced during the steady growth phase and during the light period compared to later stages and to the dark period, respectively. Salinity affected the LER more severely with increasing leaf number, probably as a result of the longer exposure to salinity and longer elongation zones for higher leaf numbers. The reduction in LER resulted from decreasing the REGR but did not result from shortening the length of the leaf elongation zone during the linear phase of leaf growth.
Published Version
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