INTERACTIVE EFFECTS OF CERTAIN VITAMINS, BIOREGULATOR AND YEAST EXTRACT ON SWEET PEPPER STEM AND LEAF ANATOMY UNDER TWO TYPES OF SALINITY.

All salinity types at 2000 mg/L increased stem diameter due to an increase in pith diameter, cortex thickness, width of epidermis cell and vascular bundles dimensions (length as well as metaxylem vessel diameter). In addition, CaCl₂ and NaCl+CaCl₂ 1:1 (w/w) were the most effective in this respect. In addition, high salinity level (4000 mg/L) decreased most of the studied anatomical parameters. While, the pith diameter and number of vascular bundles were decreased only under NaCl at 4000 mg/L. On the other hand, pre-soaking seeds in selected chemicals used, in most cases, showed  a positive effect on the stem structure and AsA at 50 mg/L or SA at 75 mg/L was the most effective in this respect.
Low level of all salinity types (2000 mg/L) increased midrib region thickness due to increasing the length of main vascular bundle. While, the highest  salinity level (4000 mg/L) led to a decrease in this respect due to the decrease in length of main vascular bundle. In addition, NaCl was more effective in this respect followed by NaCl+CaCl₂ (1:1). On the other hand, the leaf blade (lamina) thickness was also decreased in plants grown under NaCl at 4000 mg/L followed by NaCl+CaCl₂ (1:1) due to a decrease in the thickness of palisade and spongy tissues as well as upper and lower epidermis width. Moreover, the application of chemicals used led to an increase in the thickness of midrib region as compared with untreated plants. In addition, SA (75 mg/L), AsA (50 mg/L) and α-tocopherol (100 mg/L) were more effective. In most cases, AsA at 50 mg/L or SA at 75 mg/L alleviated the harmful effect of salinity level (4000 mg/L) on midrib region and lamina thickness as well as the main vascular bundle dimensions when compared with untreated plants. Furthermore, AsA at 50 mg/L was more effective than the remaining treatments.