Two pots experiments were conducted at the Experimental Farm of El-Qassasin Horticultural Research Station,
Agricultural Research Center, Ismailia Governorate, Egypt, during two successive seasons of 2016/2017 –
2017/2018, to investigate the effect of potassium silicate at (0, 4, 6, and 8 cm3/l) as a foliar spray under different
levels of water salinity (tap water, 1000, 2000 and 3000 ppm) on Calendula officinalis L. plant. The experiment was
performed in complete randomized block design as factorial experiment with 3 replicates. The obtained results
cleared that using salinity levels decreased growth parameters (plant height, number of branches/plant, fresh and dry
weights of herb/plant), flowering parameters (flower diameter, number of flowers/plant, fresh and dry weight of
flowers (g/plant) during eight cuts and fresh and dry weight of flowers (g/plant/season)) and chemical constituents
(chlorophyll a, chlorophyll b, carbohydrate and carotenoid contents) compared to control. Moreover, the highest
values in these parameters were registered by potassium silicate at 8 cm3
/l concentration. Proline content increased
in leaves with using saline water at 3000 ppm + potassium silicate at 8 cm3
/l. Generally, it could be concluded that
potassium silicate at 8 cm3
/l, showed a uniform impact in alleviating inhibition of Calendula officinallis L. plant
growth and productivity under moderate salinity stress condition.