Distichlis spicata is a potential pasture species for salt-affected lands. However, its performance has been poor during cooler overcast weather. An experiment was established to investigate the importance of high light intensities on the growth and salt excretion of Distichlis spicata var. yensen-4a in a controlled environment glasshouse in Melbourne, Australia. The plants were grown in quartz sand with basal nutrients incorporated while a 1 cm water table was maintained at the bottom of the pot. Treatments included two salt concentrations of 1 and 4 g NaCl/kg sand, with either full light, or shaded to exclude 90% of the light.. Plants were allowed to establish in fresh water before the salt treatments and shade treatments were imposed. Measurements taken included total dry matter production, leaf osmolarity, net photosynthetic rate and leaf transpiration.

Net photosynthetic rate was shown to decrease under low light levels at the low salt concentrations, however there were no differences at the higher salt concentration. Overall dry matter production decreased with the high salinity treatment. However, the light level did not affect dry matter production. Transpiration rates were higher in the full sun treatments than in the shade treatment. Salinity did not have any effect on the transpiration at low light levels, but transpiration was reduced by the high salinity treatment when grown in full sun. Leaf osmolarity was not affected by light treatments, but was increased by 45% with the higher salt treatment. We conclude that salinity concentration is more critical than light levels for the performance of D. spicata.