And didja notice they're growing them in a simulated Martian atmosphere? They weren't stuck in simulated Martian soil in an Earth-like atmosphere, but a Martian one! That offers real possibilities, I think.
I simply doubt that is true as the article said the pressure on Mars is 0.6% of standard. They may lower pressure some what but not 99.4%.
You're doubting that the NASA's agricultural research center partner CIP managed to create an atmospheric pressure 0.6% of Earth's mean sea level pressure? Did you know you can create your own vacuum experiment at home, right? You can have roughly 0 pascals of air pressure right in your own living room.
I am sure they lowered the pressure but I am fairly confident that the plants could not survive at 0.6% the atmospheric pressure. Especially since it involves almost no oxygen (mostly CO2). You can make sugar with CO2 but you need O2 to burn that sugar for biological activity. Just think back to biology 101 if you ever took it. Hell, the plant's cell walls would rupture at such low pressures.
They're simulating the martian environment, and they're finding signs of success. These aren't lightweights, these are agricultural experts who have the backing of NASA.
Also at pressures so low liquid water would be a problem at most temperatures. Remember temperature pressure curves from physics?
Not clearly, as high school was some 18 years ago, but I'm sure the people at NASA are familiar with it.