Abstract: The experiment was carried out during kharif season of 2014 at Department of Rice, Tamil Nadu Agricultural University, Coimbatore-3. The objective of the experiment was to study the influence of photothermal indices on morphological, physiological, phenological characteristics and yield traits of rice under different sowing windows. The different sowing windows and photothermal indices influences the morphological characters of twelve rice genotypes. Among the sowing dates, the rice genotypes sown on June 9th sowing reflected significantly higher plant height, total dry matter production, number of leaves, flag leaf length and flag leaf angle. Regarding genotypes, the long duration genotype CB-05-022 recorded significantly better morphological characteristics which leads to produce better grain yield.Concerning the photothermal indices i.e. growing degree days, photothermal units, heliothermal units, heat use efficiency and radiation use efficiency was recorded maximum under June 9th where, they took longer vegetative growth duration to produce higher grain yield by utilizing heat units and natural resources efficiently under favorable weather conditions.