PERFORMANCE OF NEW PROMISING GENOTYPES OF WHEAT UNDER DIFFERENT NITROGEN AND SALINITY LEVELS OF IRRIGATION WATER

Plant growth and yield of wheat crop in saline soils and water may be increased by optimum fertilization management. The aim of this study was to investigate the response of new promising wheat genotypes to various nitrogen levels under various irrigation water salinity levels.To achieve this aim two experiments were conducted at the Experimental Farm of Dierab Station, Faculty of Agriculture and Food Sciences, King Saud University, Riyadh city, Kingdom Saudi Arabia during 2008/2009 and 2009/ 2010 seasons. The experiment was laid out in strip-split plot design with three replications. The vertical plots were allocated with three salinity levels of irrigation water (1000, 2000 and 4000 ppm). The horizontal plots were assigned to three nitrogen levels (100, 200 and 300 kg N/ha). While, the sub-plots were devoted to seven genotypes (KSU 101, KSU 102, KSU 104, KSU 105, KSU106 and Youkora Rojo).  
The main results could be summarized as follows; the salinity levels significantly affected the yield and yield components of wheat whereas, they were significantly decreased as salinity level was increased up to 1000 ppm. The optimum nitrogen rate was 200 kg N/ha. The new released genotypes showed superiority against the commercial variety i.e. Youkora Rojo under normal and salinity conditions. The best released genotype was KSU102 followed by KSU 101 and KSU103.
Increasing nitrogen rate at high salinity level of irrigation water is not favorable, whereas it significantly decreased wheat grain yield and main yield components. By the way, 200 kg N/ha was the optimum under salinity conditions. The new tested wheat variety confirmed its salinity tolerance rather than common American variety.
It can be concluded that, fertilizing wheat genotype KSU102 with 200 kg N/ha could be recommend to maximizing wheat productivity under salinity conditions.