Effects of transient waterlogging on the growth and yield of winter wheat (Triticum aestivum L.) in lysimeters
The growth and yield of winter wheat was studied after waterlogging
at different stages of growth under outdoor conditions, using lysimeters
(80 cm diameter, 135 cm deep) containing undisturbed monoliths of sandy
loam and clay soils, and cylinders (20 cm diameter, 100 cm deep) filled
with sandy loam. Soil oxygen concentration fell from 20% to 3% or less
after waterlogging to the soil surface for five days at 12°C, but after up
to 21 days at less than 5°C.
Winter wheat was most sensitive to waterlogging before emergence, when
sixteen days of waterlogging killed all seedlings. Six days of waterlogging
depressed plant populations by 88% (clay) and 61% (sandy loam) but compensatory
growth limited yield losses to around 18%.
After emergence, wheat survived surface waterlogging for up to 120 days.
In several experiments on the sandy soil, grain yields were depressed by
around 8% after waterlogging for seven weeks during seedling growth, six
weeks during tillering, and three weeks during stem elongation. Losses of
grain from one experiment on the clay were 16% and 12% respectively at the
latter two stages of growth. On both soils, yield losses were largest when
yields were high (10 t ha-1), and small when yields were low (4 t ha- and
influenced by disease, late frosts and high summer temperatures.
Waterlogging increased leaf chlorosis, and depressed tillering,
although ear numbers were less affected. Tiller survival appeared related
to soil nitrogen availability; waterlogging increased nitrous oxide concentrations,
and decreased the nitrate loss in drainage, indicating average
denitrification losses of around 12 kg N ha-1. Additional nitrogen fertilizer
after winter waterlogging increased ear numbers and grain yield, and
a higher proportion of the nitrogen in a winter waterlogged crop was
obtained from fertilizer nitrogen than in the freely drained crop.