TEMPERATURE REGULATION OF GROWTH AND ENDOGENOUS ABSCISIC ACID-LIKE CONTENT OF TULIPA-GESNERIANA L

The ontogenetic changes of dry matter and abscisic acid(ABA)-like content in the component organs of T. gesneriana ''Paul Richter'' and ''Golden Melody'' under 2 temperature storage regimes were determined. The organ dry matter and ABA showed marked differences during 13 and 5.degree. C dry storage and during subsequent growth at 13.degree. C. Scale dry matter of both cultivars declined sharply when grown at 13.degree. C. The basalplate of the cultivars showed an initial gain in dry matter, but subsequently declined. The shoot of both cultivars stored at 13.degree. C exhibited greater dry matter gain than at 5.degree. C. The bulblets of the cultivars at 5.degree. C showed a much higher rate of dry matter accumulation than at 13.degree. C. An inhibitory substance extracted from tulip bulb organs co-chromatographed with authentic ABA and had identical thin layer chromatographic RE [mobility relative to the front] values of ABA in 5 solvent systems. The total ABA content per bulb increased 3-fold in ''Golden Melody'' and 2- to 4-fold in ''Paul Richter'' during the course of the temperature treatments. ABA was low in the scales and shoot, but it was high in the basalplate, bulblets and roots. The probable ABA biosynthetic sites of tulip bulb may be the developing bulblets, basalplate and roots.