A field experiments were carried out in season of 2013/2014 at Botanical garden, Botany and Microbiology Dept., Fac. of
Sci., Al- Azhar Univ., Nasr City, Cairo, to study the effect of foliar applications of some bio-stimulants (dry yeast extracts, arginine,
B12 and their interactions) on growth, total yield, quality and some chemical constituents of wheat plants. Results showed
that, foliar spraying of wheat plants with bio-stimulants especially yeast extract had a significant effect on vegetative growth,
yield and quality. Shoot fresh weight of wheat plants were improved by yeast extract at all doses and B 12 foliar application
during the first stage. Results showed that addition of any of these treatments has been significantly increased the dry weight of
roots during two stages as compared to the control in almost cases. The contents of pigments of wheat plants showed, significant
increases in chlorophyll a, b, a+b and carotenoids content in response to various treatments. Results indicated that foliar
application of all these treatments increased amylase activity compared to control during the second stage. Application of yeast
(6 g l-1) + B12 or yeast (6 g l-1) + arginine showed the heaviest 100 seeds weight (4.16 and 4.11 g) respectively as a compared
with untreated plant(2.9 g). Moreover it could be concluded that foliar spraying of yeast (4g/l) +Arg. led to obtain the highest
values of yielded seeds protein, while the highest values of yielded carbohydrates at yeast (4g/l) +B12 of wheat plants.