Distribution of Assimilates in Gladiolus grandiflorus as Affected by Water Deficit

The distribution patterns of photosynthesis products derivedfrom ¹⁴CO₂ and of applied ¹⁴C-sucrose were studied in floweringgladiolus plants (Gladiolus grandiflorus cv. Eurovision) irrigatednormally or water stressed. Even small stresses led to a decreasein the mobilizing ability of the inflorescence and an increasein that of the corm. The stress caused a great reduction in¹⁴CO₂ fixation, and, to a lesser degree, a delay in assimilatetranslocation out of the source leaves. In all cases, well irrigatedor stressed, the corms had the highest water potential (leastnegative), followed by the inflorescences and the leaves. Thegreater the stress, the greater were the differences betweenthose organs. It is proposed that under water deficit the waterpotential of the main sink (inflorescence) decreases and itsturgor dependent growth is slowed down, so reducing its mobilizingability, and causing delayed translocation out of the leaves.The water potential of the corm — the competitive sink— remains high enabling its growth to continue and assimilatesare attracted to it. ¹⁴C-distribution, corm, flower, Gladiolus grandiflorus, water deficit, water potential