The role of agrometeorological and agrohydrological indices in the phenology of wheat in central Greece

In this study the relationship between several agrometeorological and agrohydrological indices related to temperature, humidity, precipitation and solar radiation as well as yield is examined. The agrometeorological and agrohydrological indices computed and used in this study are: heat unit, cumulative rainfall, effective phototemperature, nyctotemperature, photothermal unit, vapor pressure deficit and crop-drying days. Factor analysis was employed to indicate the significance of each parameter during various phenological stages. The agrometeorological and agrohydrological indices are correlated with the yield of wheat in two areas of central Greece, namely: Larissa (for the years 1957-1980) and Trikala (for the years 1963-1980). The results suggest a grouping, of the nine parameters that were used, in three main factors explaining 87% of the total variance of the data. It has been found that temperature and rainfall are the factors explaining most of the total variance of the data set. The contribution of humidity was also significant, especially during the last phenological stages of wheat. These results can be explained by the climatological conditions that prevail in the two study areas. Overall, the results show the importance of the agrometeorological and agrohydrological indices for monitoring the development of wheat through its phenological stages. (C) 2002 Elsevier Science Ltd. All rights reserved.