Salinity-Induced Changes in Morphological and Physiological Traits of Lettuce During Early Development

The intensive use of lettuce requires both segmented and early growth studies to identify critical salinity thresholds that may pose risks. The aim of the study was to assess lettuce physiological parameters and early growth under salinity levels. The experiment was conducted in a growth chamber, in germination pots and in soil simultaneously. Three treatments were tested in four replicates: a control and two salinity levels (50 mM (level I) and 100 mM NaCl (level II). The assessed parameters were germination rate (GR), and capacity (GC) in germination pots and soil together with phenological development on BBCH scale, leaf relative chlorophyll content, leaf area, stomatal number, aperture, width and length. Higher GR seeds values were registered with salinity level II around 55% in germination pods and 40% in soil. The first true leaf (BBCH 11) appeared in the highest percentages in the control from germination pots and in the level II treatment from soil. The relative chlorophyll content and stomata feature decrease with increasing salinity dosage. Leaf area was the highest in the control treatment, followed by the 100 mM NaCl treatment. Soil alleviates the level II of salinity stress; however, it also delays the germination seen in the lettuce emergence.