الفهرس 
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Abstract
The present study was carried out at Shandaweel Res. Sta. Sohag, Cotton Res. Inst., ARC 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 turns (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 lint yield/ plant (LY/ P)
2. Thirteen selection models of modified desired gain selection index (Pesek and Baker 1969&1970)
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 plants along with the check strain were planted on March 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) were 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), and lint index (LI; g). After picking at the end of the season the characters recorded for each single plant were seed cotton yield/ plant (SCY/ P; g), lint yield/ plant (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 for LY/P
Selfed seeds of the best 20 single plants in LY/P were saved for season 2014.
2. Selection index models
Selfed seeds of the 20 superior plants for each model were saved for next season.
In the second season of 2014, the selected plants covered single trait selection for LY/ P and selection index models were planted by selfed seeds on April 1st, 2014. A randomized complete blocks design of three replications was used. The plot was single row 4m in length, 60cm apart and 40 cm between hills within a row. One row was left without planting between each two rows to facilitate selfing and plant screening. After full emergence the hills were thinned to one plant/ hill. The recommended cultural practices for cotton production were adopted throughout the growing season. The same studied characters were recorded as in the previous season. The selfed seeds of the best 10 plants for each selection procedure were saved for evaluation in the next season (2015) as in season 2014. The experimental design, plot size, and.