photo period or cooler temperatures? (or both?)

autumn had been around for ten days now and the temperatures have cooled somewhat, particularly at night, but there is not that much difference form late summer...the days are shortening though and i am wondering about events in the garden...the egg plants, cucumbers, peppers, and tomatoes are still producing away and understandably so...they have been rejoined by some broccoli that had disappeared for a time during high summer...broccoli is a cool weather crop like asparagus, spinach, arugula, and turnips to name a few..but is it a cool weather crop because of temperature or because the temperatures in the phot0 period it prefers are cool? since it isn't all that cool right now i am inclined to the latter and, as we stand to lose eighty-six minutes of daylight this month it will be interesting to see how much more broccoli develops before a killing frost...lots to explore in the garden's ecological microcosm...you can learn a lot by paying attention...if only i could focus better.