Destruction of chlorophyll in emerging seedlings of spring barley associated with environmental stresses

An unusual disorder occurred on spring barley seedlings in southern and central Bohemia in April 2005. Affected seedlings showed conspicuous bleached or straw-coloured areas on tips of the first leaves. There were very sharp, distinct, horizontal boundaries between the green basal and discoloured tip parts of the leaves. It was remarkable that these boundaries were at the same position on all affected first leaves of seedlings from the same field. Affected seedlings were randomly distributed in the fields, and their incidence ranged from about 20 to 70% according to location. When observing the meteorological data, we can suppose that colour abnormalities in emerging seedlings were associated with specific environmental stresses which affected the sensitive plant tissues in the period between 6 to 8 days after seeding. These stresses included frosty mornings followed by clear days with high solar radiation and high UV Index.