Thesis (Ph.D.) - Cairo University - Institute of African Research and Studies - Department of Natural Resources

A lysimeter experiment was conducted to evaluate the role of water regime, nitrogen fertilizer rates and splitting dose mode of application on barley growth components and grain production. Also, creation of de{uFB01}cit irrigation strategies for barley was included. In addition, the effect of mineral fertilization on N leaching to the groundwater was investigated. Three water regimes represent 100%, 80% and 60% Etc were compared, interacting with three fertilizer nitrogen rates, i.e. 120%, 100% and 80% of recommended rate required by barley crop. Nitrogen fertilizer was applied in three splitting modes. 15N-labelled ammonium sulfated was used as tracer technique to estimate %NUE and proportion of nitrogen derived from fertilizer Ndff by different barley parts. Vegetative growth parameters like plant height, spike number and length, number of grain per spike, and weight of 100 grains were variably affected by nitrogen fertilization and water management practices. It seems, in general, that combined treatment of N2 (156 kg N ha-1) applied using S3 (50, 25, 25 %) splitting mode and W2 (440 mm) water regime was the best scenario resulted in remarkable measurements. Straw yield was enhanced by nitrogen fertilizer added at N2 rate (156 kg ha-1) applied with S1 (33%, 33%, 33%) or S3 (50%, 25%, 25%) in combination with W1 (550 mm). It seems that root dry weight mainly significantly positively affected by irrigation water regimes and N fertilizer rates but not by mode of application. Grain yield of plants irrigated with W2 (440 mm) and fertilized with N2, in spite of application mode was the best among other combined treatments. Nitrogen uptake by grains was improved by W1 regime and N2 rate but not affected by splitting mode

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