the effect of sowing date on yield of millet varieties by influencing on phonological periods duration

in order to investigation of sowing date effect on yield of millet species and its impressible from duration of phonological periods and development rate, an experiment was conducted based on complete randomized block design as combine analysis in four replications at eight sowing dates (30 april, 1 jun, 31 may, 4 july, 5 august, 1 september, 2 october and 3 november) and three millet species (panicum miliaceum, pennisetum galucum and setaria italica) in research field of gorgan university of agricultural sciences and natural resources. the results of this study showed that the sowing dates and species have significant differences in mean of leaf area index (lai) and yield. first sowing date has the most lai at three species, but it has not significant different by second sowing date in yield. increase in growth duration at early sowing dates lead to increase of lai simultaneous proper temperature and day length conditions. common millet has the most lai, but foxtail millet has the most yield for longer growth period. the results of correlation coefficients of emergence rate with temperature showed that emergence rate has high correlation (r>97%) at all varieties and stemming rate influenced by temperature and day length. the least days to emergence were in (5 august and 1 september) and the least days from tillering to stemming were in (1 september).