Effect of Water Stress, Nitrogen and Organic Manure Fertilizer on Nitrogen Use Efficiency Indices and Grain Protein Content of Wheat in a Semi-arid Environment

A field experiment was conducted for two consecutive seasons during 2010/2011 and 2011/2012 on the Demonstration Farm of the Faulty of Agriculture, University of Kassala at New Half. Nitrogen use efficiencies (i.e. agronomic AE, internal IE, physiological PE and recovery RE) and grain protein content were investigated at different level of watering regimes and organic manure application of wheat (Triticum aestivum L). The watering regime treatments were irrigation every 7, 14 and 21 days, and the nitrogen fertilizer levels were zero, 43, 86 kg N ha-1 without or with 4 tons of chicken manure ha-1. Frequent irrigation, addition of high N level and organic manure significantly increased AE, IE, PE, RE and grain protein content compared to their respective treatments. Mixing of organic manure and nitrogen fertilizer increased AE, IE and RE but resulted in a slightly increase in PE than both treatments when they were added solely. Further, the magnitude of organic manure on AE, IE, RE and grain protein content was significantly greater under normal watering regime. Wheat plants under optimum conditions (frequent watering, high N level plus organic manure) used N, as indicated by AE, PE, IE and RE, more efficiently than under other treatment combination.