To get tier 3 stuff you need between 150 and 200 in the combined meters that a crop needs for both of its Tier 2 results. Pumpkin up to 100 in bar 4 will yield you a full crop of green cabbage and a full crop of only rye, i think. To get to tier 3 or a mix of tiers you'd need to get extra influence in bar 3 for cabbage and extra influence in bar 1 for wheat. The chart doesn't show the order properly, in that, to get Wheat you'd need to either do pumpkin->100bar4, then cabbage->100bar1, then plant cereal and get wheat.
Edit:
There, I fixed that picture to be a bit more explicit in terms of order, assuming 2000% plenty you can just directly plant the starter crop, the secondary, and the wanted result one each. Alternatively get starter crop to full 100 bar, then make sure to get the secondary up fast enough to match the first bar's decline. To get the wanted crop's Tier 3 you'll need 150+ total between the two bars needed. So 100 in starter bar then at least 151 total influence in both bars as the first one declines. Hope this helped.
Exactly 6.022 x 10^23 worth of Lach molecules.