Dylan and I have been working on getting hydroponic testing up and running. The basic set up is a large tub filled with dilute nutrient solution, with aeration provided by an air pump. Floating on top of the water is a large foam sheet with holes. In each hole we put a 2 ml tube packed with rock wool and perlite along with a seedling. Extending below the hole is a large bubble tea straw to make sure the roots don’t tangle together while growing.
In this initial test, the water was lightly fertilized and had no nickel, just to see how the plants would take to hydroponics. Dylan planted a couple dozen Streptanthus while I tested wild H. annuus and H. bolanderi seeds.
After one and a half weeks, the sunflowers are going strong, while the Streptanthus is very sad.
We were worried that the rock wool plug would prevent the roots from emerging, but life finds a way. All of the plants had some roots visible below the cap, and a couple extended 5 inches below the straw bottom (for a total of at least 10 inches of root. The fact that there is a prominent taproot even in hydroponics is good news for my goal of measuring tolerance by assaying taproot growth rate.
The next step is to see how nickel concentrations affect this growth…