A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca2+]and [PO43-] using tricalcium phosphate as P source in the hydroponic solution, and adding CaCl2 for supplementing extraCa2+. The system, similar to soil solutions, was a P nutrient buffer solution with very low bioavailable P. The buffersolution induced the roots of both monocotyledon and dicotyledon species to grow abundant root hairs, 3 mm inmaximum length. The monocotyledons were corn (Zea mays L.) (var. Yellow Rose), wheat (Triticum aestivum L.) (var.Yanzhong 144), Triticale secale L. (var. Jingsong 5), and ryegrass (Lolium rigidum L.) (var. Ruanni), and the dicotyledonswere Arabidopsis thaliana L. (var. Columbia), white clover (Trifolium repens) (var. Kopu), Lotus (Lotus peduncucatusCav. Luliginosus Schkuhr) (var. Grasslands Maku). For these species we proved that the root environment controls theinduction of root hair formation. However, the hydroponic buffer solution failed to induce root hairs on the roots of onion(Allium cepa L.). Other investigators have concluded that corn does not form root hairs in hydroponics, but abundantlong root hairs on corn were induced by this buffer system. The roots with abundant long root hairs are called “hedgehogroots” because they have hairs everywhere just like a hedgehog.
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