Early generation testing for vegetative and yield characters in thirty Egyptian cotton populations

Thirty F3 families, derived from selfed F2 plants of four crosses among six Egyptian cotton varieties, twenty five lines descending from three-way crosses, i.e., seven from [[Giza70 x Giza 80] x Dandra], eleven from [[Giza 80 x Giza83] x Giza45], seven from [[Giza70 x Giza 83] x Giza 88] and five lines descending from the single cross [Giza 80 x Giza88], and two check Giza 45 and Giza 80 were evaluated in a yield trial at "The Experimental Research Station" of the National Research Centre at Shalakan El-Kalyoubia Governorate in 2005. Results revealed highly significant differences between genotypes for all traits except total nodes per plant. The range of internode length varied from 4.35cm to 7.1cm with overall mean 5.39 cm. Only two genotypes had short internode length than the check variety Giza 45. The phenotypic coefficients of variation [PCV] were generally higher than its corresponding genotypic coefficients of variation [GCV]. No great difference between phenotypic and genotypic coefficient of variation was detected for boll weight, seed cotton yield, lint yield per plant and lint percentage indicating a great chance of further improvement by selection. High broad sense heritability estimates were observed for boll weight [85.1%], seed cotton yield [78.0%] and lint yield [77.2%], while moderate heritability values were found for number of open boils per plant [69.6%], lint percentage [61.6%], monopodia per plant [49.0%], internode length [42.30%], and plant height [41.6%]. High heritability was associated with high genetic advance in number of open bolls per plant [69.6% and 64.87%] seed cotton yield [78.0% and 60.69%] and lint yield [77.2% and 60.39%], proving the presence of sufficient genetic variability which help the cotton breeder to exploit it by practice most effective selection in early generations. Classical selection indices values showed that the most superior lines that should be selected are 10, 13, 17, 12 and 15, they had the highest mean performance for all traits. These genotypes were selected from the offspring of the three- way cross [[Giza 80 x Giza 83] x Giza 45]. Three-way crosses may be considered as a good tool to obtain a better homozygous progenies when tested in early generation

Evaluation of 32 F5 families derived from two interspecific Cotton crosses for late planting

32 F 5 Families derived from two interspecific cotton crosses, three parental lines and two check varieties were evaluated in season 2003 under three planting dates March 24, April 22 and May 20 at the Experimental Farm of the National Research Centre at Shalakan, Kalubia Governorate, Egypt. This was done in an attempt to; select short season cotton genotypes suitable for late cultivation after winter crops [such as bean or wheat] in Southern Delta and Upper Egypt and, to study the association between all studied traits and to identify the superior genotypes using classical selection index. Results obtained indicated that planting dates mean squares were found to be highly significant for all traits studied except position of first fruiting node. Genotypes mean squares were found to be highly significant for all traits evaluated under the three sowing dates and combined data. Combined analysis over three planting dates revealed highly significant genotypes x environment interactions for all traits except position of the first fruiting node. The average number of days to first flower for all populations studied were significantly decreased as planting date was delayed.Correlation coefficients between all possible pairs of traits studied were different in magnitudes from one planting date to another, also, the genotypic correlations were mostly higher in magnitudes than the phenotypic correlations. Path analysis revealed that boll number / plant had the highest direct effect on seed cotton yield followed by boll weight at the three sowing dates. Estimated value of selection index indicated that the ranking of cotton genotypes are not identical in the three sowing dates. It could be concluded that four lines [1,7, 14 and 27] selected in the late planting date may be exploited in breeding early cotton genotypes which tolerate heat stress in squaring, flowering and boll formation periods

Estimation of genetic parameters in the F1 and F2 generations of diallel crosses of bread wheat [Triticum aestivum L.]

A half diallel analysis of crosses among seven bread wheat varieties were usedto estimate combining ability, genetic components of variation and carry outgraphical analysis for days to heading, plant height, number of spikes/plant,main spike length, number of spikelets/spike, grain weight/spike, 1000-grainweight and grain yield/plant in the F1 and F2 generations. Highly significantdifferences among genotypes, parents and crosses were observed for all traitsin both generations. General and specific combining ability variances werehighly significant for all traits in the two generations indicating theimportance of both additive and non additive gene effects in the inheritanceof the traits studied. The estimated values of dominance components [H1 andH2] were found to be highly significant for all traits studied and higher inmagnitude in the F2 than in the F1. The three long spiked varieties [Sids 5,Sids 7 and Sids 8] were good general combiners for earliness, plant height,main spike length, grain weight/spike and number of spikelets/spike in the twogenerations, except Sids 8 in the F2 for the latter trait. Gimmeza 3 and Sids7 were the best general combiners for 1000-grain weight. The best generalcombiner for grain yield/plant and some of its components was the selectedline followed by Gimmeza-3. Estimates of F values revealed an excess ofdominant alleles in the parental lines for days to heading and grainweight/spike in the two generations. The best specific combinations for grainyield and some of its components were detected in both generations in ninecrosses. Graphical analysis revealed that partial dominance was found fordays to heading, plant height, main spike length and grains weight/spike inboth generations. Overdominance played an important role in the inheritanceof grain yield in both generations. The distribution of parental arrays alongthe regression line were widely scattered for all traits studied indicatinggenetic diversity among the parents. The relative order of the points of theseven parents along the regression line were different from one generation toanother. The results recommended using the two wheat varieties Gimmeza 3 andSids 7 and the best five hybrid combinations Giza 157 x Sids 5, Sakha 69 xSids 5, Gimmeza 3 x Sids 8 and the selected line with each of Sids 5 and Sids8 as the most promising genotypes in a future breeding program for developingnew bread wheat cultivars possessing high yielding potentiality