Some physiological responses to d,l abscisin (dormin).

The responses to synthetic d,l abscisin have been studied in a variety of tests. When fed in aqueous solution continuously to leaves of seedlings growing under long day conditions, d,l abscisin caused the cessation of extension growth and the formation of typical resting-buds in Betula pubescens, Acer pseudoplatanus and Ribes nigrum. Abscisin also inhibited the growth of non-dormant buds of potato when applied to the whole tubers, but was much less effective when applied to isolated tuber plugs.Abscisin accelerates the senescence of leaf discs of a wide variety of species, but is less effective when sprayed on to attached leaves, except at relatively high concentrations (50-100 ppm).Abscisin inhibited flower induction in the long day species, Lolium temulentum and Spinacia oleracea, when applied to the leaves during a period of exposure to 15-long-day cycles. Abscisin promoted flowering in the short-day plants Pharbitis nil, Ribes nigrum and strawberry when applied under long day conditions, but it did not induce flowering in certain other typical short day plants. Tuberization in Solanum andigena and two cultivars of S. tuberosum was promoted by abscisin when applied to the leaves of plants growing under long-day conditions.