From the experience of the son of a rice farmer (probably the first time that descriptor has been used on SDMB) there can also be agronomic advantages .
Rice is usually grown on heavy clay soils to minimise water losses. Rice spends most of it’s growing cycle during summer in “permanent water” maintained 25-35cm deep.
One of the consequences of the clay soils is muddy water which blocks the sun.
If there is low levels of salt in the water the clay particles flocculate and the water becomes clear. Consequently the sun penetrates the surface, the water is warmer which encourages greater growth.
Varieties with greater tolerance of brackish water than existing cultivars could exploit this advantage.