whta is the role of casparian strip???? what would have happened if it was not present???? 

 
When substances travel inwards from the root epidermis through the cortex, and finally arrive at the endodermis, they encounter the Casparian strip. Since it is an impermeable thickening in the cell wall, it stops materials from traveling through it, thus terminating the apoplastic pathway. Thus, it forces all substances to pass through the cytoplasm by the symplastic pathway. This is very important for the plant, as the cell wall cannot control the type and amount of substances passing through it, but the plasma membrane can. So, by forcing substances to shift from the apoplastic to the symplastic pathway, the Casparian strip allows the plant to control how much water and minerals it absorbs from the soil.
thumbs up please  *_*