Effect of shelter on the yield and water use of wheat

Abstract

Wheat was grown in the field and lysimeters under 3 experimental regimes — full exposure to wind, full shelter within an enclosure, and partial shelter behind an artificial windbreak — to test the hypothesis that a crop in a sheltered environment will be more conservative in its water use and more efficient in using that water to grow biomass. The fully sheltered wheat crop in the field produced 11% more above-ground biomass than the exposed crop and most of this difference was attributed to leaf (20%) and stem (21%) material. However, the sheltered crop had lower 1000-grain weights (35.6 g cf. 40.1 g) and higher protein (14.3% cf. 11.5%). No significant difference between sheltered and exposed yields could be confidently detected. Plants grown under non-water limiting conditions of lysimeters produced 14% more biomass under shelter and were also likely to be more efficient (7%, P = 0.06) in their use of water to produce that biomass than wind-exposed plants. Shelter did not change the total soil water use of the lysimeter- or field-grown wheat. However, the sheltered field crop was more conservative than the exposed crop in its use of soil water up to anthesis and less conservative during grain filling. In the partial shelter regime wheat was grown in the ground and in lysimeters at distances of 3 H (i.e. 3 × windbreak height), 6 H, 12 H, 15 H, 18 H and 24 H from an artificial windbreak. Significant relationships with distance from this windbreak were only observed in total biomass, stem weight and head weight of field-grown wheat at anthesis. In summary, the sheltered wheat was more efficient in production of biomass and did conserve water early in the growing season but the conserved soil water was expended to maintain that biomass at the expense of grain size.