Mechanisms of Salt Tolerance in Plants Relevant to Closed System Agriculture in Desert Environments

Closed system agriculture (CSA) in arid regions provides a method for minimizing the disadvantages of arid environments such as limited supplies of fresh water, while making maximal use of the main advantages, including abundant solar radiation and long growing seasons. The greatest advantage can be obtained from CSA if it is combined with the use of the often abundant saline ground water of many arid zones. The effective use of saline water in CSA requires development of plant varieties that can be productive under saline conditions and take full advantage of the CSA environment. This study is aimed at defining physiological characteristics which might provide easily selected or engineered traits that would lead to enhanced production of C4 plant species under CSA conditions utilizing saline water. Our findings indicate that increased carboxylation efficiency with increased salinity is a key physiological trait conferring enhanced productivity to certain species of sporobolus under saline CSA conditions. This trait can be identified by lowered CO2 concentrations in the intercellular spaces in response to salinity.