Abstract: Under Mediterranean conditions, maize Zea mays L.) grain yield is generally reduced by delayed sowing. Pioneer 31G98 was grown as early and late crop to evaluate the grain yield relations with agronomic and physiological differences between two sowing time in the Seyhan Plain in Çukurova, Turkey, which represents agroclimatic conditions, typical of those prevailing in the Mediterranean region. Maximum values for Leaf Area Index (LAI) and leaf net photosynthesis (An) did not differ between two sowing dates. The duration of LAI, An and Dry Matter (DM) accumulation decreased considerably when sowing took place late. There was a consistent decrease in the Intercepted Photosynthetically Active Radiation (IPAR) in the late sowing crop, compared with the early crop. Biomass and grain yield were significantly decreased when maize was grown as a late crop. Grain yield decrease of the late crop was resulted in lower grain weight, possible due to lower total energy and lower IPAR during the grain growth. Number of grains of both crops were similar. Thus, higher radiation use efficiencies during the grain filling must be considered to overcome maize yield decreases in the late season and under changing climate in the future in Mediterranean environments.