Income tax

They both are to be taxed individually , so NO

Also the loss is from share trading , 

So assuming security transaction tax has been paid and the shares are equity shares or unit of equity oriented Mutual fund . NO SUCH LOSS CAN BE ADJUSTED AGAINST INCOME UNDER ANY OTHER HEAD

sec 10(38) exempts the LTCG on above shares and unit

Further loss from a source which is not taxable can not be adjusted against income under any head.

If you want to save tax of the assesse who sold land

you can claim exemption u/s 54 EC (investment in NHAI or RECL ) within 6 months from date of transfer or date of filling the return u/s 139(1)

the max. amount is rupees rupees 50,00,000 in a financial year

ONLY LAND IS SOLD?

In addition you can go with exemption u/s 54F (purchase or construct a house property provided you do not have more than one house property EXCLUDING THE NEW PROPERTY ) . In case any asset other than residential property is purchased

If you had purchased property 1 year before the date of transfer then also you can claim exemption to the extent of amount LTCG or actual amount whichever is lower

(Other requirements of aforesaid sections are also to be fulfilled)

NO, we cannot set off wife's LTCG with Husband's LTCL and reduce the tax liability.