Field experiments were performed at the Agricultural Experiments and
Researches Station, Faculty of Agriculture, Cairo University, Giza, Egypt during the
two growing seasons of 2002 and 2003 to study the effect of foliar application with
stigmasterol at various concentrations of 0,25,50,100 and 200 ppm on morphological,
anatomical and yield characters as well as on seed quality of soybean cv. Giza 35. Results revealed that foliar application with stigmasterol at the relatively low
used concentration of 25ppm or at the relatively high used concentration of 200 ppm
showed no significant effect on all studied morphological characters of vegetative
growth of soybean cv. Giza 35. By contrast, foliar application with any of the two
assigned median concentrations of 50 and 100 ppm stigmasterol induced significant
promotive effects on main stem length, number of branches and leaves per plant,
total leaf area per plant and shoot dry weight per plant of soybean cv. Giza 35.
Worthy to mention that the maximum promotive effect induced in vegetatiVe growth of
soybean was detected at 100 ppm stigmasterol. As to the effect of foliar application with 100ppm stigmasterol on anatomical
structure of vegetative growth of soybean cv. Giza 35, it could be stated that such
treatment increased stem diameter due mainly to the prominent increase in the
thickness of epidermis, cortex and vascular cylinder although a slight reduction in pith
diameter was observed. Ukewise. spraying stigmasterol at concentration of 100 ppm
increased thickness of both medvein and lamina of leaflet blades of soybean cv. Giza
35. The increase in lamina thickness was accompanied with increments in thickness
of palisade and spongy tissues. Also, the main vascular bundle of the midvein was
increased In size as a result of spraying stigmasterol. Concerning the effect of stigmasterol on yield characters and seed quality of
soybean cv. Giza 35, it was found that all adopted concentrations of stigmasterol
showed no Significant effect on number of seeds per pod and percentage of total
lipids in seeds of soybean cv. Giza 35. Number of pods per plant, number of seeds
per plant and yield of seeds per plant were increased significantly and linearly with
increasing the concentration of stigmasterol up to 100 ppm and then decreased
sharply when using stigmasterol at concentration of 200ppm. Moreover, foliar
application with any of the two aSSigned median concentrations of 50 and 100 ppm
stigmasterol induced significant promotive effects on specific weight of seeds and
percentage of crude protein in seeds of soybean tv. Giza 35, and the difference
between these two median concentrations proved indifferent in this respect. The
maximum significant increase in seed yield per plant was recorded at 100 ppm
stigmas~erol, being 44.4% more than seed yield per untreated plant of soybean cv.
Giza 35.