UC Irvine

Summary: Applications of ABA to Cymbidium flowers induce some, but not all, post‐pollination symptoms. Anthocyanin levels in sepals, petals, columns and labella are raised; flowers wilt; dorsal sepals become hooded; calli develop colouration while losing turgidity; columns do not swell, lose very little curvature; and stigmas do not close. Combinations of ABA and NAA induce all post‐pollination phenomena, but lower anthocyanin content than treatments with ABA only. ABA plus GA3 have effects which are similar to those of ABA alone, except that anthocyanin levels are reduced. The same is essentially true of ABA‐kinetin mixtures but intensities of the effects are different and with some concentration ratios, stigmatic closure also occurs. The effects of ABA and its interactions with GA3, kinetin or NAA are explained in terms of the roles these hormones may play in synthesis of nucleic acids and enzymes.