Advantages of a novel pH measurement for soilless media.

Rhizosphere pH determines nutrient bioavailability, but this pH is difficult to measure. Standard pH tests require adding water to growth media. This dilutes hydrogen ion activity and increases pH.

Photocontrol of flowering and stem extension of the intermediate-day plant Echinacea purpurea.

Intermediate-day plants (IDP) flower most rapidly and completely under intermediate photoperiods (e.g., 12-14 h of light), but few species have been identified and their flowering responses are not well understood.