The effect of short-term chilling on the water metabolism in wheat as related to optimal and excessive zinc content

The effect of short-term chilling (to 4°С for 1 day) on the growth and water metabolism in winter wheat (Triticum aestivum L.) when combined with optimal (2 ﾊM) and excessive (1000 ﾊM) zinc content in the root area was studied in a controlled environment. In the plants growing in a medium with optimal zinc content a 1 day exposure to the 4°С temperature caused a reduction of the stomatal pore size, a decline in stomatal conductance and transpiration rate. These modifications supposedly act as defensive adaptations meant to maintain a high water content in the leaves and support the increment of the above-ground biomass. Where the metal concentration in the root area was excessive, there was a heavier decline in stomatal conductance and transpiration rate, and yet the water content in the leaves somewhat decreased. Furthermore, plants in this treatment demonstrated a partial closure of stomata and a considerable decrease in their number. The above changes in the stomatal system together with a slower increment of the root biomass pointing to inhibition of their growth must have been the main reasons for a disruption of the water metabolism in the wheat plants exposed to a low temperature coupled with excessise zinc content in the root area.