Response of water stressed maize (Zea mays L.) at different growth stages to selected nitrogen fertilizers

This study was conducted during seasons 2004, 2005 and 2006 at Gezira Research Station Farm, Wad Medani, Sudan. The areas within the semi-arid, climate at the intersection of latitude 14 deg 24/ and longitude 33 deg 31/, and at an altitude 411 m asl. The objectives were to determine the effect of N-fertilizer and water stress on maize, examine the influence of water and nitrogen on yield and yield components; identify physiological traits associated with moisture stress, and evaluate nitrogen uptake and nitrogen use efficiency (NUE). The first experiment was laid in a split-plot design with three replications, using Hybrid H-351 from Egypt. The treatments comprised of two irrigation regimes viz: normal (every 10 days) and stress (every 20 days), in the main plots. The three fertilizer sources; urea, ammonium sulphate (AS) and ammonium sulphate nitrate (ASN)), each with three rates; 0, 43 and 86 kg N/ha, were assigned to the subplots. The second experiment was arranged in a split split plot design, with three replications. The treatments comprised of four irrigation types in the main plots i.e. normal irrigation (WI); skipping one irrigation at vegetative stage (W2); at flowering (W3) and at grain filling (W4); using two maize varieties H-351 and Mugtamaa-45, in the subplots and three rates of nitrogen as urea; 0, 43 and 86 kg N/ha in the sub subplots. Irrigation regimes revealed significant differences in most of the traits tested. The effect of moisture stress was manifested in the reduction of yield and yield components. Treatments W3 and W4 negatively affected grain yield, causing a reduction of about 10 to 45 %. Application of nitrogen fertilizer depicted significant effect on most of the tested parameters, whereas results showed that they significantly and positively responded to increased nitrogen application. The interaction effect was significant mainly for both grain yield and total biomass, which increased with increasing nitrogen level. However, under water stress both grain yield and total biomass showed no significant effect. Positive responses between WP and each of grain yield and biomass were detected under normal irrigation. Application of AS and ASN significantly increased the percentage of oil content. The hybrid variety gave higher grain yield and biomass than Mugtama-45. Grain yield was significantly and positively correlated with most of the traits used in the evaluation