Effects of waterlogging and drought on winter wheat and winter barley grown on a clay and sandy loam soil

Summary

The effects were investigated of waterlogging and drought on winter wheat and winter barley growing in a clay soil, and winter wheat growing in a sandy loam. The crops were grown in lysimeters that were waterlogged or freely-drained between December and March, and then irrigated or subjected to drought from April to harvest.

On the clay soil drought restricted water use and dry matter production by wheat and by barley. The effect on water use was proportionately greater than on dry matter production. On the sandy loam drought decreased water use by wheat, but had only a small, non-significant, effect on dry matter production. Measurements made with a neutron probe in lysimeters that had been subjected to drought showed that the maximum amount of water that winter wheat could extract from the clay soil was 150 mm, and from the sandy loam was 170 mm. Winter barley could extract 114 mm from the clay soil. On both soils transpiration by wheat and barley was restricted when about three quarters of the available soil water had been extracted. Drought decreased leaf water potential and stomatal conductance.

Waterlogging in the winter decreased dry matter production and water use in the summer, but not by causing plant water stress in the summer. Plants that had been waterlogged had higher leaf water potentials and stomatal conductances in the summer, and dry matter production was decreased more than water use.

There was no evidence that waterlogging in the winter made the drop more vulnerable to drought in the summer.