Effects of severe water stress on partitioning of ¹⁴C-assimilates in tomato plants

Abstract

Tomato plants (Lycopersicon esculentum Mill. cv Nikita) were grown hydroponically and subjected to severe water stress induced by addition of PEG-6000 to the nutrient solution. The PEG-treatment clearly impaired growth. Leaf photosynthesis decreased during the experiment. Moreover, the decrease in photosynthesis was associated with a decrease in dry weight of the shoot compared to the root. Also leaf area expansion, stomatal conductance and transpiration decreased. Water stress enhanced the transport of 14C-assimilates from the source leaf to the lower parts of the plant where the assimilates were incorporated in the lower stem, the leaves below the source leaf and the roots. It was observed that 14C was much more concentrated in the roots compared to the other plant parts.