Seasonal variation of leaf colour in Syrian barley and its association with photosynthetic electron transport rate

Abstract

Leaves, formed at later developmental stage, in barley genotypes native to Syria are lighter green than those adapted to wetter areas. In the present study, six barley genotypes were objectively assessed for leaf colour throughout a cropping season. Leaf colour was measured by using a chroma meter. The L* a* and b* axes provide a three-dimentional coordinate space of colour that relates to human perception. L* measures psychrometric lightness. The a* axis transects the red and green hues, while the b* axis transects the blue and yellow hues. Syrian landraces showed considerably higher L* indicating that they have a lighter leaf colour. They had higher a* and lower b* values than those of dark-green group until February, and then turned to lower a* and higher b* values thereafter. This indicated ťhe leaves of Syrian landraces had lesser green and yellow hue in winter than in spring. The relationship between leaf-colour variables and the photosynthetic electron transport rates were also explored both in winter and in spring. It is considered that low chlorophyll content and/or higher chlorophyll a/b reduces the risk of damage from photoinhibition.