Germplasm Enhancement for Water Stress Tolerance and Storage Insect Resistance in Bread Wheat (Triticum aestivum L.)

This study was carried out during three successive seasons 2004/05, 2005/06 and 2006/07, to evaluate fifty F derived lines (from the F diallel cross), with three check varieties under two different irrigation regimes. 3 2 Twenty different lines were selected from the fifty F lines under each level of irrigation and evaluated under 3 the same conditions in the F and F generations. Also, the effect of irrigation regime on insect infestation of 4 5 stored grains for six F selected lines under each level was studied. F results revealed that highly significant 5 3 differences were obtained between the two irrigation regimes for all traits studied. Highly significant differences among genotypes were obtained in normal (L ) and water stress conditions (L ) as well as in their combined 1 2 data for all traits studied except grain yield / plant in combined data only. F results revealed that highly 5 significant differences among F selected lines were found for all traits studied at the two irrigation regimes. 5 Estimated values of selection index indicated that the ranking of lines are not identical in the two irrigation regimes. The best superior lines were identified under each level; twelve F lines were selected under normal 3 irrigation condition (L ), eight F lines under water stress condition (L ). Drought susceptibility index were 1 3 2 also estimated and detected the more superior genotypes under water stress environments. Results of correlation studies under stress conditions indicated that, grain yield /plant under water stress was significantly positive associated with no. of spikes / plant in both the F and F generations with high 3 5 magnitude in the F . The selection for drought tolerance has improved the magnitude of correlation between 5 important yield components and yield under water stress conditions. High estimates of heritability were noted for all traits in the F comparing to F estimates except 100 grain weight in the F at normal level (L ). 5 3 3 1 Concerning insect resistance results showed significant variation between wheat lines for their infested grain in all storage periods. Interaction between lines and irrigation levels was found to be highly significant in all storage periods. The arrangement of the studied lines based on their insect resistance was different from one irrigation regime to another.