What kind of crop can be grown at high salinity?

Scientists have developed a seed-producing crop that thrives in sandy soils irrigated with salt water. The crop, derived from a wild halophyte, Salicornia bigelovii, yields seeds rich in high-quality oil and protein.

I was going to say sea weed but that is probably not what you are looking for.

There is a table toward the bottom of this article that shows the relatively sensitivity to soil salinity in various crops.  Note that each table has the least sensitive at the top and goes down to the most sensitive at the bottom.  The bigger the number in the table, the less sensitive the crop is.  The numbers in the table represent the salinity in terms of the electrical conductivity tests they perform on the soil.  

The least sensitive field crops listed are barley, sugarbeets, and wheat.
The least sensitive forage crops listed are tall wheatgrass, wheatgrass, and crested wheatgrass.
The least sensitive fruits/vegetables listed are broccoli, cucumber, and cantaloupe, though you can tell by the numbers that these are much more sensitive to salinity than the field crops or forage crops are.

The salt tolerance of a crop may be appraised according to three criteria:

    * Ability of the crop to survive on saline soils
    * Yield of the crop on saline soils
    * Relative yield of the crop on a saline soil as compared with its yield on a nonsaline soil under similar growing conditions.


Scientist are developing plants that thrive in salt water and salty soils may help alleviate severe food shortages in developing countries. Such as:  Salt-Tolerant Tomatoes
they are sweeter, tastier tomatoes, and melons made more salt-tolerant through crossbreeding are being grown with drip irrigation in desert settlements in Egypt and Israel.
Date Palm has a high level of salt tolerance. Fig, pomegranate, cantaloupe, grapes and olive crops are among those economically important fruit plants which are recorded to have grown on moderate saline conditions and thus have salt-tolerance. Among vegetables: garden beets, asparagus, spinach are few crops registered to have grown on salty soil and water conditions. Field crops such as barley, rapeseed, and cotton are highly salt-tolerant crops. And rice, corn and sorghum are crops which can be grown in moderate salinity.