Light absorption and light extinction in barley (Hordeum vulgare L.) as affected by planting dates and plant genotypes

Plant light absorption and extinction may affect plant growth and yield. A split plot experiment (with three replications) was carried out in the Research Field of Agricultural College, Islamic Azad University, Isfahan, Iran, during 2011–2012 in order to determine the influence of light absorption and extinction on barley growth and yield. Planting dates including Oct 10th (P1), 25th (P2), and Nov 10th (P3) and plant genotypes including Nosrat (N), 4Shur (S), and Fajr 30 (F) were used as the main- and sub-plots, respectively. Plant growth and yield as well as crop light absorption and extinction were determined at different growth stages. Using a light meter, the rate of photosynthetically active radiation of canopy in the range of 400–700 nm was determined (41–57%). Light extinction coefficients (0.355–0.485) were also determined according to the Beer-Lambert law. Planting dates and genotypes significantly affected crop growth, yield, and response to light. S resulted in the highest rate of light extinction and absorption at P1 and P3, respectively, and it also resulted in the highest rate of grain yield (4228 kg ha −1 ) and harvest index (40.9). These results indicated the positive correlation between the growth and yield of barley genotypes with light absorption and extinction. Such findings can be used for a more efficient designing of a barley canopy with higher growth and yield.