الفهرس 
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Abstract
The present study was carried out at Shandaweel Res. Sta. Sohag, Cotton Res. Inst., A.R.C. during the three summer seasons of 2013-2015. The basic materials were seeds of 60 single plants selected from the breeding nursery of renewing and maintenance of Giza 90 (G.90) according to field evaluation and laboratory determinations in 2012 season. The selfed and open pollinated (natural) bolls of each plant were picked and ginned separately (the same materials used to produce G.90 nucleolus). G. 90 is traced back to a cross between Giza 83 × Dandara, and released commercially in season 2000. G.90 is a commercial Egyptian cotton cultivar (G. barbadens L.) cultivated at Upper and Middle Egypt regions and characterized by high yielding ability, high ginning out turn (more than 120 pounds), and early maturity with staple length of about 31 mm.
These materials were subjected to evaluate three methods of pedigree selection as follows:
1-Single trait selection for seven characters.
2-Independent culling levels of ten characters.
3-The traditional method followed by Cotton Maintenance Res. Sec. for renewing and maintenance of Egyptian cotton varieties, represented by the check strain (the newest nucleolus of Giza 90) in the experiments every year.
In season 2013 selfed seeds of each of the 60 selected plant along with the check strain were planted on March on 28th, 2013 in a plot in the breeding nursery. Each plot included five rows 7.0 m long, 60 cm apart and 70 cm between hills within a row (10 plants in a row). The middle row was left without planting to facilitate plant screening and selfing. At flowering self-pollination was done for the best plants in the breeding nursery, and days to first flower (DFF) was recorded for each plant (the total number of selfed plants were 847). Before picking ten open sound bolls were picked from each plant to measure boll weight (BW;g), seed index (SI;g), lint index (LI;g). After picking at the end of the season the characters recorded for each single plant were seed cotton yield / plant; g (SCY/P; g), lint yield / plant; g (LY/P; g), lint percentage (Lint %), number of bolls/ plant (NB/P), number of seeds / boll (NS/B), Micronaire reading (Mic), fiber strength as Pressley Index (PI) was measured by the H.V.I instrument and Upper half mean length (UHM); mm was measured by the H.V.I. instrument.
Selection procedures
1-Single trait selection
Selfed seeds of the best 20 single plants in seven traits were saved for season 2014. The seven traits were days to first flower, boll weight, lint %, number of bolls / plant, seed index, lint yield / plant and lint yield / plant which earlier than the population mean (LY/p restricted by DFF