Selection for seed cotton yield plant -1 was applied in F2, F3 and F4-generations of a population of cross Giza 80 X Giza 90 cotton. The experiment was carried out during three successive summer seasons; 2019, 2020 and 2021 at farm west of Minia, El Minia under new reclaimed lands conditions. Entries mean squares of the selection criterion; seed cotton yield were significant or highly significant in F3 and F4-generations. Reduction was observed in the phenotypic and genotypic coefficients of variability from F3 to F4 compared to the phenotypic variation in F2 for the most studied traits as a result the selection for seed cotton yield/plant and reduction the genetic variation. Moreover, increasing the homozygosity. The four selected families of no. 13, 17, 18 and 26 were showed highly significant increase compared to both bulk and better parent for the two traits seed cotton yield and lint yield plant -1 . Seed cotton yield /plant was showed positive genotypic and phenotypic correlation coefficients with bolls weight, lint yield /plant -1 and number of bolls plant -1 . While, negative correlations were observed for Seed cotton yield / plant with each of lint percentage and lint index on genotypic and phenotypic levels.

Selection for seed cotton yield plant -1 in a segregating population of cotton of cross Giza 95 x Super Giza 86 was applied under new reclaimed lands conditions for three summer season, 2019, 2020 and 2021 at Mallawy Agriculture Research station, west of El Minia. The wide range of seed cotton yield/plant in the F2-generation from 16.40 to 186.00 gm. Indicating ability effective selection for seed cotton yield. Entries mean squares of the selection criterion; seed cotton yield and lint yield/plant and number of bolls/plant were high significant in F4generation. Estimates higher than 82.71% of heritability for the seed cotton yield, lint yield/plant and branches/plant. Two families; No. 6 and 9 were higher than the better parent Giza 95 and bulk sample in each of seed cotton yield, lint yield/plant and number of bolls /plant in the F4-generation. Four selected families no. 2, 6, 9 and 20 were showed significant (p≤0.05 or 0.01) increase compared to the bulk in seed cotton yield/plant by 19.26, 50.03, 32.16 and 64.26%, respectively. The seed cotton yield per plant showed strong positive genotypic and phenotypic correlation with each of lint yield per plant by 0.99 and bolls number/plant 0.97 and 0.95, respectively. Moreover, low positive correlation with boll weight, seed index, fiber length and uniformity index, with negative correlation with each of lint percentage, fiber fineness, lint index and fiber strength.