Effects of salinity on the photosynthetic pigment composition of barley (Hordeum vulgare L.) grown under a triple-line-source sprinkler system in the field

The effects of salinity on the flag leaf photosynthetic pigment contents and photosystem two efficiency have been studied in several cultivars of barley (Hordeum vulgare L.) in four growing seasons. Barley was grown in a triple-line-source sprinkler system, that maintains a linear soil salinity gradient. Salinity induced minor increases in the flag leaf total chlorophyll content, bur: did nor cause significant changes in the relative pigment. composition. The photosynthetic pigment stoichiometry of flag leaves was in the ranges 20-40: 100-200: 110-180: 90-150 : 230-230 : 1000 (mol:mol) for neoxanthin: V+A+Z pigments:lutein: p-carotene: chlorophyll b:chlorophyll a. We observed changes in the pigment stoichiometry from year to year, indicating that the pigment composition of the flag barley leaf depends markedly on the environmental conditions, The actual efficiency of photosystem two, measured at full sun in the field with modulated chlorophyll fluorescence techniques, had small changes in response to salinity in the triple-line-source sprinkler system, whereas the non-photochemical fluorescence quenching increased in response to moderate salinity.