Hard to answer your question for plant populations, but here is something to go by.

On a square 160 acre field, here is what your drone will provide.

Altitude Time Batteries Resolution Images Storage
393 ft - 36m - 2 - 3.3cm/px - 766 - 6.4 GB
196 ft - 130m - 5 - 1.6cm/px - 3117 - 26 GB
131 ft - 280m - 9 1.1cm/px - 7051 - 59 GB



All of these figures are with 80% picture overlap.

Time to process will vary greatly, based on computer processing speed.

Hope that helps you figure things out.

edited to hopefully make the numbers make more sense