Effects of phenological stages, growth and meteorological factor on the albedo of different crop cultivars

Albedo is a key component of the atmospheric, climatologic and remote sensing studies by means of global warming, energy balance, evapotranspiration, climate models, hydrological cycle etc.  For these reasons, the accurate determination of surface albedo has become more important. In this study, the variation of measured albedo values of winter wheat, barley and sunflower cultivars according to phenological stages was investigated for the first time in the northwestern part of Turkey. Additonally, influences of leaf area index as growth indicator and rainfall as meteorological variable on albedo were also analyzed. The average albedo values of winter wheat, barley and sunflower in both growing periods varied from 0.176 to 0.190 for winter wheat, from 0.171 to 0.189 for sunflower and from 0.187 to 0.214 for barley cultivars. According to phenological stages, the minimum and maximum average albedo values were found for winter wheat as 0.121 between sowing and germination and 0.247 between stem formation and head emergence; for sunflower as 0.150 between sowing and germination and 0.212 between leaf initiation and immature bud; for barley as 0.144 sowing and germination and 0.261 between head emergence and flowering stages. Additionally, significant relationships were found between albedo and leaf area index for winter wheat, barley and sunflower as r2=0.87, r2=0.82 and r2=0.77, respectively.