I think the green tint in the desert, especially the early shots with the droids, is party due to them using a green/grey filter to achieve a day for night/twilight effect, when filming at those times wasn't practical, isn't it? There's a whole mix of brightness conditions that aren't consistent for advancing day, depending on when they were able to film (sometimes in the bright of day with the cameras' iris almost completely stopped down, producing the odd glaring, somewhat blurry, unfocused effect.).

In the SE's one or more of the replaced sandcrawler shots shows it almost being twilight/ nightfall. A bit strange, because when they get to the farm it actually appears brighter and earlier, again. I guess they could have gone through a night period, then day and arrived at the farm almost a whole day later, but it's not obvious..