Abstract

This experiment was conducted during two successive seasons 2001 and 2002 at two experiment Stations (Al-Taji and Al-Madain). The aim was to increase genetic variations bygamma rays. Seeds of 21 genotyps were irradiated by gamma rays (200 Gy). Irradiated seeds were planted in the field with the control ones. During different stages of M1 generation plant growth the percent of emmergense, growth development number of days to flowering and mean of bolls/ plant were measured .The results in (M1) generation showed a reduction in growth development (plant height) of all irradiated genotypes by 9, 7, 17, 8, 19.5 and 41.7 cm for 45, 105, 165, and 185 days and 10.3, 18.1, 26.3 and 43.7 cm for 45, 105, 165, and 185 days from date of planting in Al-Taji and Al-Madain station respectively. The mean of percent of emmergense was reduced by 36% and 35% in the both station respectively. In M2 generation several variants were obtained (2998 and 333 genetic variants from the both Station.
The genotypes 12 and 18 gave a high number of varients 25 and 27 in Al-Taji and 31 and 25 varients in Al–Madain. The same genotypes gave a high number of variants whish have a big boll 11 and 17 varients from the both genotype. It is recommended to use 200 GY dose of gamma ray on cotton, and the genotypes 12 and 18 was the best.