Matthew Poole and continuators on Exodus 9:32

32 But the wheat and the rie were not smitten: for they were not grown up .

The Hebrew word may be rendred either dark or hid, to wit, under the ground, whereby it was secured from this stroke: or late, as divers of the Hebrews and other Interpreters render it. This kind of Corn coming later up, was now tender and hidden either in the ground, or in the Herb: whereby it was in some measure secured both from the fire by its greenness and moisture, and from the hail by its pliableness and yielding to it, whereas the stalks of Barly were more dry and stiff, and therefore more lyable to the Hail and Fire.

Marginal references: Heb. hidden or dark.