Leafy Greens Have Circadian Rhythms, Too

Photo: thebittenword.com Just like humans, plants respond biologically to the cycle of days and nights, called circadian rhythms. Now, a team of biologists has discovered that even after produce has reached the grocery store, it benefits from cycles of daytime and nighttime lighting.

As reported by Popular Science, the biologists experimented on a member of the mustard seed family, which includes cabbage. They exposed the plants to 12-hour periods of lightness and darkness, and found that they produced a compound called glucosinolates during the simulated daytime.

They repeated the same experiment with circles of cabbage leaf cut from the plant, and discovered that they still produced the glucosinolates during the light periods. And, compared to circles of cabbage leaf that were exposed to all lightness, or all darkness, those exposed to the 12-hour alternating periods were least-eaten by caterpillars-- and glucosinolates are a natural insect repeller.

In addition to warding off caterpillars, glucosinolates may be healthy for consumers. Some preliminary research shows that they could be partially responsible for lower rates of cancer in people who eat lots of cruciferous vegetables (like cabbage and broccoli).