The present invention provides a method for determining a level of a RuBP, PGA, 2-PA in a photosynthetic cellular extract by resolving at least one RuBP, PGA, or 2-PA or combinations thereof in a photosynthetic cellular extract obtained from a plant. In another aspect, it provides for detecting at least one resolved RuBP, PGA, or 2-PA or combinations, thereby determining a level of the resolved RuBP, PGA, or 2-PA or combinations. In one aspect the photosynthetic cellular extract is obtained from a plant subjected to an abiotic stress. A method of the invention can be useful, for example, for identifying plants with increased photosynthetic performance. Also included herein is a high throughput system for identifying a plant with increased photosynthetic performance.