Question

what does salanio say about knapped ginger

Answer 1

Solanio said the above statement in context with the rumors of Antonio's shipwreck

he said that may the rumour be as false as of the lady who chewed ginger to pretend that she's crying for the death of her third husband

in other words solanio used the word ginger to express fakeness

Answer 2

Knapping or eating ginger is said to increase the will for pleasures of the bed

So, Solanio here means that while the woman is making her neighbours believe that she is sad about the death of her third husband, she is actually eating ginger and thus looking forward to enjoying her next marriage.

Hope this helped!

;)