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A field experiment was conducted during kharif season, 2016 at S.V. Agricultural college, Tirupathi to study the Influence of Agroclimatic indices on yield and yield attributes of maize (Zea mays L.). The experiment was laid out in split plot design with twelve treatments. Three maize hybrids D.S 900M, Pinnacle and CP818 with four dates of sowing (June II FN, July I FN, July II FN and August I FN). The results indicated that the number of days to attain different phenological growth stages varied. Among the hybrids Pinnacle recorded numerically higher yield (3006.58 kg ha-1) than D.S 900 M (2748 kg ha-1) but was significantly higher than CP818 (2678.4 kg ha-`1) Among the dates of sowing D1 (June II FN) recorded significantly higher yield (3684.36 kg ha-1) than D2 (3207.72 kg ha-1), D3 (2628 kg ha-1) and D4 (August I FN) recorded significantly lower yields (1724.26 kg ha-1). Pinnacle and June II FN recorded highest accumulated Growing degree days, Heliothermal Units, Photothermal units and Heat Use Efficiency to reach maturity compared to the all other treatments. Buildup of GDD, HTU and PTU are good estimators to study maize phenology and can be used as a reliable tool to optimize the sowing period for different maize cultivars.

Key words: Grain yield, Growing degree days, Heliothermal units, Photothermal units and Heat use efficiency.