Water use efficiency of rainfed and irrigated bread wheat in a Mediterranean environment.

In West Asia and North Africa, shortage of water limits wheat (Triticum aestivum L.) production. Current irrigation practices aim at maximizing grain yield, but achieve lower return for the water consumed. Maximizing water use efficiency (WUE) may be more suitable in areas where water, not land, is the most limiting factor. We examined the effects of various levels of supplemental irrigation (SI) (rainfed, 1/3 SI, 2/3 SI, full SI), N (0, 5, 10, 15 g N m -2 ), and sowing time (Nov., Dec., Jan.) on evapotranspiration (ET) and WUE of wheat. WUE was calculated for rain (WUE,), for total water (gross: rain + irrigation) (WUE g ), and for SI water only (WUE SI ). ET ranged from 246 to 328 mm for rainfed crops, with grain yield ranging from 130 to 270 g m -2 and total dry matter from 380 to 1370 g m -2 . Irrigated crops had ET of 304 to 485 mm, with grain yield of 170 to 500 g m -2 . The degree to which water supply limits grain yield was indicated by the ratio of pre- to post-anthesis ET (2.1-2.4:1). The SI treatments significantly increased WUE g : from 0.77 to 0.83 to 0.92 kg m -3 in November and December sowings for 1/3 SI and from 0.77 to 0.92 kg m -3 in November sowing for 2/3 SI. The highest WUE g and WUE SI were achieved at 1/3 to 2/3 SI. WUE was substantially improved by applying 5 and 10 g N m -2 , with little increase for higher rates. Delaying sowing had a negative effect on WUE for both irrigation and rainfed conditions. In this rainfed Mediterranean environment, WUE can be substantially improved by adopting deficit SI to satisfy up to 2/3 of irrigation requirements, along with early sowing and appropriate levels of N.

[1]  M. Pala,et al.  Assessment of the Effects of Environmental Factors on the Response of Wheat to Fertilizer in On-farm Trials in a Mediterranean Type Environment , 1996, Experimental Agriculture.

[2]  Peter J. Gregory,et al.  Effects of fertilizer, variety and location on barley production under rainfed conditions in Northern Syria 2. Soil water dynamics and crop water use , 1987 .

[3]  H. C. Harris,et al.  Improving Water use Efficiency of Annual Crops in the Rainfed Farming Systems of West Asia and North Africa , 1987, Experimental Agriculture.

[4]  J. Passioura.  Physiology of Grain Yield in Wheat Growing on Stored Water , 1976 .

[5]  E. R. Perrier and A. B. Salkini,et al.  Supplemental Irrigation in the Near East and North Africa , 2012, Springer Netherlands.

[6]  R. French,et al.  Water use efficiency of wheat in a Mediterranean-type environment. I. The relation between yield, water use and climate , 1984 .

[7]  D. Tennant,et al.  Water Use and Water Use Efficiency of Old and Modern Wheat Cultivars in a Mediterranean-type Environment , 1990 .

[8]  W. K. Anderson,et al.  Yield advantage of two semi-dwarf compared with two tall wheats depends on sowing time , 1990 .

[9]  W. Anderson.  Increasing Grain Yield and Water Use of Wheat in a Rainfed Mediterranean Type Environment , 1992 .

[10]  W. K. Anderson.  Differences in response of winter cereal varieties to applied nitrogen in the field I. Some factors affecting the variability of responses between sites and seasons , 1985 .

[11]  Theib Oweis,et al.  Stabilizing Rainfed Wheat Yields with Supplemental Irrigation and Nitrogen in a Mediterranean Climate , 1998 .

[12]  Heping Zhang,et al.  Water-yield relations and optimal irrigation scheduling of wheat in the Mediterranean region , 1999 .

[13]  J. Passioura,et al.  Roots and drought resistance , 1983 .

[14]  Peter J. Gregory,et al.  Effects of fertilizer, variety and location on barley production under rainfed conditions in Northern Syria 1. Root and shoot growth , 1987 .

[15]  M. G. Bos.  Irrigation efficiencies at crop production level. , 1980 .

[16]  J. Keatinge,et al.  Crop evapotranspiration — a technique for calculation of its components by field measurements , 1983 .

[17]  J. Eastham,et al.  Growth of shoots and roots, and interception of radiation by wheat and lupin crops on a shallow, duplex soil in response to time of sowing , 1996 .

[18]  H. C. Harris,et al.  Assessing the productivity of wheat genotypes in a Mediterranean climate, using a crop-simulation model , 1989 .

[19]  J. Schultz,et al.  Effect of time of sowing on wheat phenology in South Australia , 1979 .