The present study was conducted on potato plant (Solanum tuberosum L. cv. Spunta) during the two successive seasons of 2002 and 2003, using five
concentrations of EM1 stock solution (1, 5,10,15 and 20 mUL) compared with control
plants. The first three concentrations of EM1 induced significant increases -in plant
height, number of stems/plant, number of leaves/plant, total leaf area / plant, number
of tubers / plant and weight of tubers / plant, in both studied seasons. Treatment 5 ml
EM1/L gave the highest values in most of the investigated morphological and yield
characters compared to control plants. While, the other used two concentrations of 15
and 20 ml EM1/L induced significant decrease in all of the previous studied
characters. Anatomical studies were made on plants treated with 5 and 15 ml EM1/L
which gave the extreme differences in morphological characters compared with
control. Treatment of 5 ml EM1/L gave the thickest roots, stems and leaves.