Figure 1.

Abiotic stress results in a range of changes attempting to optimise light absorption and energy balance of photosynthesis.

(A) Common to all abiotic stresses, is the need to optimise light absorption and energy balance to avoid photoinhibition and allow acclimation. Sustained or high intensity stresses cause irreversible damage the photosystems and other cellular components leading to cell death. (B) Salinity, an abiotic stress factor, acts in two phases; the osmotic and the ionic. The osmotic phase is a rapid response, which results in stomatal closure and growth rate reduction. It is referred to as a shoot-ion independent effect, as the ions have not had time to accumulate to toxic levels in the shoot. It is followed by the ionic phase, which causes early leaf senescence (Munns and Tester, 2008). Reproduced with permission of Annual Review of Plant Biology, Volume 59 © by Annual Reviews, http://www.annualreviews.org. (C) Energy absorbed by the photosystems can be used in one of three ways: for photosynthesis, released as chlorophyll fluorescence or released as heat through non-photochemical quenching.