الفهرس 
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Abstract
Drought is considered as one of the most important limiting factors for seed yield and oil percentage of canola plant (Brassica napus L.) . The present research was concerned with studying the productivity of thirteen canola genotypes under three irrigation intervals (12, 24 and 36 days). This study carried out at the Experimental Farm (Demo ”new reclaimed soils”) of the Faculty of Agriculture at Fayoum, Fayoum University, during the two successive seasons 2012/2013 and 2013/2014. The design was split plots arranged in randomized complete block with three replications. Therefore, the irrigation intervals were allocated in the main plot and genotypes of canola in sub-plot. The results indicated highly significant and significant differences among irrigation (I) intervals, genotypes and their interaction (I x G) in both seasons. This indicated the presence of appreciable level of differences among genotypes for most of the studied traits and justifies carrying out further genetic analysis. The individual means comparison of irrigation intervals (I’s) reduced by increasing drought stress, and, I3 treatment caused severe reduction in most traits compared with I2 one. The genotypic trait means under normal (I1) irrigation (12 days) were higher than those of drought conditions (I2 and I3), indicated that these traits were greatly influenced by water deficit. The genotypes 12, 10, 11 and 9 surpassed other genotypes for most traits in both seasons under drought stress.
Genotypic and phenotypic variances were high for the traits; number of pods/plant, plant height, seed yield /plant and height to 1st branch while for number of branches /plant, seed index, seed yield / feddan and oil percentage had low values. Mostly, the phenotypic coefficient of variability was greater than those of genotypic one for all studied traits. Heritability (broad senses) was low to moderate values. Also, genetic advance (GA) values were Low to moderate values for all studied traits except number of pods/ plant (high value). Genetic advance as percent of mean (GAM %) seemed to more important than GA values for further improvement in the tested genotypes.
The assessment of different drought stress indices (mean productivity (MP), stress tolerance index (STI), geometric mean productivity (GMP), yield index (YI) and yield stability index (YSI) tolerance index (TOL) and stress susceptibility index (SSI)) revealed that among all genotypes tested in this study G3 and G2 and their F4 hybrid (genotype 11), G2 x G3 and their backcrosses (genotypes 10 and 12) are the most drought tolerance genotypes supporting the idea that different gene could be involved in the inheritance of drought tolerance in canola. The correlation coefficients between drought tolerance indices and seed yield /feddan under stress and non-stress conditions in both seasons, showed that the stress tolerance index (STI), yield index (YI), tolerance index (TOL) and geometric mean productivity (GMP) were powerful indices for identifying drought tolerance of canola genotypes.