الفهرس 
Physiological and chemical traitsOnly 14 pages are availabe for public view
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Abstract
The present investigation was carried out at the extension field in tanta Gharbia Governorate, during the two successive seasons 2014/15 and 2015/16. Nine lines and four testers of wheat (Triticum aestivum L.) were used. In 2014/15 season, lines and testers were crossed by line x tester model to give 36 top crosses . In 2015/16 season, the lines, testers and 36 F1’s were planted in a randomized complete block design with three replicates, each parent and F1 was represented by two rows per replicate. Each row was 1.5 m long; spaces between rows were 30 cm with 15 cm between plants. Measurements comprised physiological and chemical, vegetative and yield and its components characters. Physiological and chemical characters; chlorophyll A (mg/cm2), chlorophyll B(mg/cm2), chlorophyll A/B, carotene content, flag leaf area (cm2), flag leaf angel, nitrogen in leaf and protein in grain. While, vegetative characters; days to heading (day), days to maturity (day), plant height (cm), growth rate, no. of tillers/ plant, spike length (cm), spike petiole length (cm) and no. of spikelets / spike. Meanwhile, yield and its components characters; number of spikes/plant, number of grains/spike, 1000-grain weight (g), straw yield (g), harvest index %, grain yield/plant (g). The obtained data for each character were analyzed on plot mean basis. An ordinary analysis Line x Tester was performed according to Kempthorne (1957) and heterosis as proposed by Mather and Jinks (1982). The obtained data could be summarized as fallows: 1- Analysis of variances: Estimation of the analysis of variance showed highly significant differences among genotypes for all the studied traits. These results indicated that genotypic differences among genotypes were present. Partitioning sum of squares due to genotypes revealed significant or highly significant differences among parents, crosses and parents vs. crosses for all the studied traits, except for chlorophyll B for parents and for chlorophyll A/B, flag leaf area, plant height, growth rate, spike petiole length, no. of spikelets / spike and 1000-grain weight for parents vs. crosses. Crosses was partitioned into lines, testers and line x testers interaction. The mean squares of lines, testers and line x testers showed significant or highly significant values for all the studied traits, except for nitrogen in leaf, protein in grain and grain yield/plant for lines, chlorophyll B, chlorophyll A/B, carotene content, nitrogen in leaf, protein in grain, days to maturity, growth rate, number of grains/spike and straw yield for testers and straw yield for L x T. These results indicated that lines differed in their order of performance in crosses with each of the testers. The ratio of 2gca/2sca showed values less than one for all studied traits, except for straw yield in which this ratio exceeded the unity. This might indicate that the non-additive gene effects were more important than the additive gene effects for the inheritance of all studied traits, except for straw yield in which additive gene effects more important than non-additive gene effects. Summary 83 2- Means performance: The parental line L5 and the crosses( L1 x T1 ) , (L5 x T3) ,( L9 x T2), and( L3 x T1) showed the best values for physiological and chemical traits. The crosses;( L2 x T1) and ( L2 x T2) were the best crosses for earliness and the cross;( L5 x T2) and ( L4 x T2 )for other vegetative traits . The parental tester T2 and the crosses (L5 x T1), ( L7 x T4) and (L6 x T3) showed high values for grain yield and its components. 3- Combining ability analysis: The results of combining ability analysis of cultivars can be used in hybrid breeding program to facilitate the breeder’s decision when they are selecting the cultivars. A- General combining ability effects: The tester parent ( T2 ) was considered as a good combiner tester for chlorophyll A, flag leaf area and angel and nitrogen in leaf, the line parent (L3) for chlorophyll A/B, the line parent (L4) for chlorophyll B and the line parent (L5) for protein in grain. The parent (L2, L3, L7 and T2) was considered as agood combiner parents for earliness. While, the tester parent (T3) for short plant height, spike length and no. of spikelets / spike, the line parent (L4) for no. of tillers/ plant, the line parent (L5) for growth rate and the tester parent (T4) for high plant height and spike petiole length had desirable significant gca effect. Summary 84 The line parent (L7) was considered as a good combiner parent for no. of grain / spike, 1000-grain weight and harvest index, the line parent (L4) for no. of spikes / plant. While, the lines parent (L8) and (L9) for straw yield and the tester parent (T4) for grain yield/ plant had desirable significant gca effect . B- Specific combining ability effects: The crosses;( L1 x T1 ) and( L2 x T2 )showed desirable and significant (s^ ij) values for physiological and chemical traits. The crosses;( L4 x T2),(L5 x T2 )and L7 x T1 )showed desirable and significant (s^ ij) values for vegetative traits. The crosses (L5 x T1), (L6 x T3) and (L7 x T4) showed significant (s^ ij) values and positive for grain yield and its components. 4- Heterosis percentage: The crosses;( L2 x T2) and ( L4 x T2) had desirable and significant heterosis over mid and better parents for physiological and chemical traits. The crosses; ( L4 x T2) ,( and L7 x T2 ) had desirable and significant heterosis over mid and better parents for vegetative traits. The crosses; ( L5 x T1 ) and ( L7 x T4) showed significant and positive heterosis over mid and better parents for grain yield and its components.