Breeding Behaviour Of Some Characters I An Egyptian Cotton Hybrid:

Mohamed Mahmoud Awaad

Eight inbred lines descendant from the cross (Giza 83) I (line22/80), in addition to the two parents of the cross were grown atseven locations. i.e.; Sakha. Bahtim. Giza. Sids. Maghagha,El-Ioussiaand El-H1nshah in 1987 season. A randamized complete block designwith six replications was used. The standard analysis of varianceand stability of preformance were made for each of the charactersunder the study. The result,s obtained could be summarizedas follows:1- The relative magnitudes of the genotype-environment interaction:-Highly significant mean squares for environments were obtainedfor all characters. The genotypic differences were significant orhighly significant for all characters under study except number ofbolls per plant, seed cotton yield and lint yield characters. Themean squares of genotype-environment interaction were significantor highly significant for all characters except number of days tofirst flower. earliness percentage and the 2.5 % span length. Theseresults indicated that cotton as well as other crop varieties oftenshoweddifferent responses ~len grownunder different environments. ;11- The genotypic stability for different genotypes : The relative ranking o.f genotypes according to their mean performanceover the seven environments was not the same for all characters.Lines 50/85 and 48/85 were the earliest and highest yieldingamongthe other genotypes.• iWl.threspect to genotyp:1cstability analysis. all of the cbaracters(except, num.berof dSJ·s to first flower, earliness percentageand 2.5% span length) showponent of variance (the dethat the relatively unpredictable com-,.from linear response. A.. ) of thegenotype-environment may be more important than therelatively predictable compon nt (the linear response. ~ ).IIEstimations of genoty c stability revealed varying degreesof stability for the genotypes. This study shows that themost stable genotype over e seven sampled environments was line63/85 which exhibited hest number of stable characters. followedin a descending variety and lines. 44/85. 53/85.50/85, 22/80, 59/85, 48/85. Giza 83. and 61/85. Apparently,the lines with high mean valu had below average degrees of stability,Ilines with poor mean performs ce had above average stability and linesMany workers reported t the stability with which the plantwith average mean performance howed average stability in this study.breeders are concerned does imply general constancy of phenotypein varying environments, but stability in agriculturallyimportant characters (Allard and Bradshaw, 1964; Eberhart and Russel, 1966; Tai, 1971). Therefore. the genotypes53/85, 44/85 and SO/85 which ibited high yielding ability and werestable in one or more of th traits studied in the present investigationcould be selected. III- Estimation of heritabilit enetic advance under selectionand enetic coefficient 0 variabilit ..1- High heritability value (over 50%) were observed for earliness/characters. boll weight. lint seed index, lint index andall of the fiber propertie The high heritability values wereapproximately, consistent f all the seven environments. Moderateheritability estimates, (fro 30 to 50 %), were obtained for numberof bolls per plant. Howeve, low heritability values (below 30%)were obtained for yield chara terse2- High excepted genetic advance (over 7%) were observed for theposition of first sympodiumand seed index. Moderate genetic gains,(from 5% to 7%) were est :ed for earliness percentage, number ofbolls per plant, and micronaire reading. While, lowgenetic gains, (below 5%), w e calculated for days to first flowering,yield characters, lint perce tage , lint index and all the other fiberproperties.3- The genetic coef£ici at of variability was intermediate’ onlyfor the position of first, :rmpodiWDh,owever, it was small for the other characters.