The plant hormone abscisic acid (ABA) induces a morphological change from green vegetative cells to red cyst cells, of Haematococcus pluvialis containing carotenoids, in plate culture. Long-lasting analogs of ABA, (+)-8＇,8＇,8＇-trifluoro and (+)-8＇,8＇-difluoro-ABAs, which can resist metabolic inactivation, induce carotenoid production at 100-fold lower concentration than (+)-ABA. These analogs can be used as effective regulators to produce carotenoids in H. pluvialis cells.