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

ABSTRACT

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