Effects of UV-B radiation on oxalate content of silver beet leaves

Silver beet (Beta vulgaricus var. cicla) a common vegetable in New Zealand is known to contain high levels of oxalates in the leaves. Silver beet plants were grown in a field trial under glass and perspex sheets which filtered sunlight reaching the plants. After eight weeks of growth, the plants were harvested and the total, soluble and insoluble oxalate content of the leaves of the plants grown under the two filter treatments and a no-frame control were measured. Perspex allowed the transmission of UV-A, UV-B and photosynthetically active radiation (PAR), whereas glass excluded UV-B radiation. No significant differences between the perspex treatment and the no-frame control were observed when the data was compared on a wet matter (WM) or dry matter (DM) basis. Shielding the growing plants with glass significantly reduced the total oxalate and soluble oxalates to 83 and 84% respectively when compared to the perspex and no-frame treatments