Robinson, M., The Hebrew University of Jerusalem, Department of Ornamental Horticulture, P.O. Box 12, Rehovot 76 100, Israel
Halevy, A.H., The Hebrew University of Jerusalem, Department of Ornamental Horticulture, P.O. Box 12, Rehovot 76 100, Israel
Galili, D., The Hebrew University of Jerusalem, Department of Ornamental Horticulture, P.O. Box 12, Rehovot 76 100, Israel
Plaut, Z., The Hebrew University of Jerusalem, Department of Ornamental Horticulture, P.O. Box 12, Rehovot 76 100, Israel

The distribution patterns of photosynthesis products derived from 14CO2 and of applied 14C-sucrose were studied in flowering gladiolus plants (Gladiolus grandiflorus cv. Eurovision) irrigated normally or water stressed. Even small stresses led to a decrease in the mobilizing ability of the inflorescence and an increase in that of the corm. The stress caused a great reduction in 14CO2 fixation, and, to a lesser degree, a delay in assimilate translocation out of the source leaves. In all cases, well irrigated or stressed, the corms had the highest water potential (least negative), followed by the inflorescences and the leaves. The greater the stress, the greater were the differences between those organs. It is proposed that under water deficit the water potential of the main sink (inflorescence) decreases and its turgor dependent growth is slowed down, so reducing its mobilizing ability, 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 assimilates are attracted to it. © 1983 Annals of Botany Company.