Abstract: A produce-ripening room (1) has a pallet rack (8) designed to support one or more modular pairs of two loaded pallets (11) juxtaposed side-by-side with a select space between them for central distribution of conditioned atmosphere under pressure throughout produce crates (12) positioned on the pallets (11). The modular pairs of two loaded pallets (11) can be one-to-three tiers high, up to twelve tiers deep and as many tiers wide as desired stacked bin boxes may be substituted for the pallets. A top horizontal baffle (22) is positioned vertically above and extended from end-to-end over depth of the select space between the modular pairs of two loaded pallets (11) and seals (26, 27, 36, 37) are positioned on four sides of the select space to provide a central high-pressure plenum (25, 34) for a first embodiment.