Water use and water-use efficiency of wheat and barley in relation to seeding dates, levels of irrigation and nitrogen fertilization

Abstract

Response of timely and late seeded wheat ( Triticum aestivum L.) and barley ( Hordeum vulgare L.) to three levels of irrigation and four rates of nitrogen was investigated under pre-seeding irrigation. Water extraction pattern and water use of these crops varied markedly. Barley outyielded wheat by 27 and 9%, but used 9 and 21 mm less water, when one and two irrigations were given at critical stages, respectively. These results indicate the possibilities of considerable saving of water (100 mm) for barley without any decrease in grain yield and increased water-use efficiency (WUE) of wheat and barley by irrigating at critical stages as compared to irrigation at 75% depletion of available soil water (ASW). In general WUE decreased with increase in irrigation frequency and delay in seeding. Nitrogen fertilization with marginal additional water use (4–9%) increased yield linearly (45–98%) and thus increased WUE of wheat and barley. This additional water was extracted from below 60 cm depth at tensions ⩾ 1.5 MPa and particularly in maximum growth and reproductive stages. These results suggest that barley should be preferred to wheat under medium to severe water stress and late seeding conditions.