Gravity, we all know it, if only from falling to the ground when we were kids, or dropping a glass of lemonade (or worse). But did you know that plants use gravity to navigate? Roots grow in soil, deeper and deeper; they follow the direction of gravity. Stems on the other hand use gravity as well, but respond the exact opposite way; they grow against the direction of gravity.
These pea plants were placed horizontally at the start of the video, watch the synchronicity. Images were taken every 30 seconds, frame rate is 25 fps.
Slightly younger pea plants than in the video above are tilted early in the video. Images were taken every minute, frame rate is 25 fps.
Arabidopsis thaliana (thale cress) seedlings on a transparant agar plate (square Petri dish), approximately 5 days old. We tilted the plate 90 degrees twice. Look how beautifully the roots follow gravity! Pictures taken every 4 minutes, frame rate is 35 fps.
Tomato plant in so-called rhizotron, a thin layer of soil between two plates, one transparent. Although the shoot shows beautiful negative gravitropism (growth against gravity), the roots in this video respond poorly, simply because they don’t grow that much (but check the green arrow!). We will make some more attempts, expecting to show clearer root gravitropism in the future. Pictures were taken every 2 minutes, frame rate is 50 fps.
Tomato plant put horizontal about 2 hours before the video starts. School project with one of our kids, we have not kept the exact info in image frequency and frame rate but what you are seeing is approximately happening in 5 hours. We used a free app on our cellphone for this one.