"tHE SUCCESSFUL breeding program depends on genetic variability response to selection, heritability and genetic advance. The present investigation aimed to estimate
these components in two intra-specific cotton crosses (Giza 92 x Giza 87 and Giza 96 x Giza
87) during early segregating generation. Most of the studied traits showed high broad sense heritability coupled with low or moderate genetic advance as percent of mean in F generation. So, these traits controlled by non-additive gene action. The analysis of variances for F families
showed highly significant differences between F

families and variance within F was lower
than among families for all the studied traits over the two crosses. All F families had low intra- class correlation values over the two crosses, so selection between families is better than within families. The additive genetic variance was larger than dominance variance for all the studied traits except for seed cotton yield / plant and lint %, also, these traits showed partial degree of dominance for cross I. While, cross II has higher values of dominance genetic variance than additive variance for all traits except for boll weight and fiber length, so that showed overdominance. Selection differential and response to selection were found to be positive for all traits during F and F . The probability of new recombinant lines falling outside parental range
2 3
was higher in cross I than cross II for all traits except for boll weight and fiber length. The study
reveals that judicious selection leads to improvement in next generation.
"

The breeding material used in this study consists of five parental cotton genotypes and their derived four F 1 and F 2 generations. The study was carried-out at Sakha Experimental Station, Agricultural Research Center, Kafr El-Sheikh, Egypt. The genotypes were evaluated to estimate the genetic components such as additive and dominance genetic variances, broad sense heritability and gain from selection using 5 % selection intensity in F 2 generation. Mean performance of the studied genotypes differed significantly for all the studied characters of four crosses. The estimates of Euclidean or straight line between five parental cotton genotypes were highly significant indicating the wide genetic dissimilarity and reflecting their different origin. Yield characters had positive values with right skewness for crosses I, III and IV, while, fiber quality characters had both directions. Crosses I, III and IV had negative kurtosis values for most yield and fiber characters expect, cross II which has positive sign for all the studied characters, except fiber strength and fiber length. Most estimates of additive genetic effect [a] were smaller than the dominance genetic effect [d] for the studied characters of four cotton crosses, except seed cotton yield in crosses I, III, and IV and lint percentage for crosses I and III. Correlated response was low between all the studied characters of the four crosses, except between boll weight with seed cotton yield, lint yield and lint percentage and between lint yield with seed cotton yield, their correlated response was very high. So, indirect selection for one of these characters could improve the others.

The experiments were carried out at Sakha Agriculture Research Station, Cotton Research Institute, Agriculture Research Center, Egypt. The aim of this investigation was to study heterosis and combining ability for the most important characters of cotton (seed cotton yield, lint yield, boll weight, seed index, lint percentage, lint index and hallo length). Ten cotton genotypes TNB, Karsheneski2, G.45, G.89 x G.86, G.86, G.94, G. 93, CB.58, G.75 x Sea and Australian12 were crossed in half diallel. These parents and their respective 45 F1 crosses were evaluated in a randomized complete blocks design. The results obtained could be summarized as follows:- Highly significant mean square values were obtained for genotypes, general combining ability and specific combining ability for all the studied characters. The best general combiner for all studied traits were parents G.94 and G.75 x sea. Also the best combination for most of studied characters were crosses G.45 x CB 58, TNB x Aus.12, Kar.2 x G.94, G45 x CB 58, G.94 x (G.75 x sea) and G.93 x (G.75 x sea). The first three principle components were significant and accounted about 90.3% of the total variability of all characters. Which having maximum Eigen value. Lint index followed by lint percentage, boll weight and lint yield were a primary source of variation in the first ax. The second ax was principally affected by seed cotton yield and hallo length. The ten parents in this study were grouped in different clusters and there were accordance between parental diversity and significant general and specific combining ability.

Improving cotton breeding programme must depend on the amount of genetic variability between the parental genotypes, which is the main source of genotypic variation among the progeny. The present study was undertaken for the estimation of genetic variability, genetic components and heritability for some yield characters in F2, F3 and F4 generations derived from two cotton crosses. Estimated Prediction of new recombinant in F3 generation and selection was done on F2 to select the most promising plants and the most superior F3 families and plants within each selected family. The results showed some genetic variation among three studied generations, which reflect genetic variability between studied generations. Dominance genetic variance was more important than additive genetic variance in most studied characters. These results indicated that these characters are controlled by non-additive gene type. The analysis of variance for F3 generation showed significant differences between F3 families and it’s greater than within families in all the studied characters over the two cotton crosses, which show presence of high genetic variability in F3 generation. This reflects low values of intra-class variability. So, selection is more effective between families rather than within families. Correlation and regression results between generations showed that F2 was not good indicator of F3 progeny, while this trend changes from F3 to F4 generations. Prediction for new recombinant failing outside parental range through F3 generation was higher for all the studied characters. Realized selection differential was higher between and within selected F2 plants and F3 families. So, the grand mean values of these selected plants and families were higher than grand mean of F2 and F3 population. Selection between segregating generations coupled with high heritability is a good indicator for selecting promising plants in F2 generation and most superior families within F3 families and within each family.

The experiments were carried out at Sakha Agriculture Research Station, Cotton Research Institute, Agriculture Research Center, Egypt. The aim of this investigation was to study heterosis and combining ability for the most important characters of cotton (seed cotton yield, lint yield, boll weight, seed index, lint percentage, lint index and hallo length). Ten cotton genotypes TNB, Karsheneski2, G.45, G.89 x G.86, G.86, G.94, G. 93, CB.58, G.75 x Sea and Australian12 were crossed in half diallel. These parents and their respective 45 F1 crosses were evaluated in a randomized complete blocks design. The results obtained could be summarized as follows:- Highly significant mean square values were obtained for genotypes, general combining ability and specific combining ability for all the studied characters. The best general combiner for all studied traits were parents G.94 and G.75 x sea. Also the best combination for most of studied characters were crosses G.45 x CB 58, TNB x Aus.12, Kar.2 x G.94, G45 x CB 58, G.94 x (G.75 x sea) and G.93 x (G.75 x sea). The first three principle components were significant and accounted about 90.3% of the total variability of all characters. Which having maximum Eigen value. Lint index followed by lint percentage, boll weight and lint yield were a primary source of variation in the first ax. The second ax was principally affected by seed cotton yield and hallo length. The ten parents in this study were grouped in different clusters and there were accordance between parental diversity and significant general and specific combining ability.

Successful cotton breeding programs focus initially on developing new genotypes with high yields and improved fiber quality. The main aim of this work was to determine the inheritance of yield and fiber quality of an extra long staple (ELS) variety in two crosses with long staple parents and to determine the variability in F2 populations. Hybridization between the Egyptian extra-long staple (ELS) cotton variety Giza 88 as a female parent pollinated by the long staple varieties, Giza 86 in cross I and Suvin in cross II in 2014 season. Parents and both F1 and F2 generations were grown in a randomized complete block design during 2016 season at Sakha Experimental Station Farm, ARC. Data were recorded on individual plant basis for the studied traits. The studied genotypes, parents and both F1 and F2 generations were significantly different for all the studied traits, reflecting the genetic diverse back ground of these parents. The variation due to parents vs. F2 generation was also highly significant for most of the studied traits. The long staple varieties (Giza 86 and Suvin) had the higher mean performance for yield and its component traits whereas the extra long staple variety (Giza 88) gave the highest values for fiber properties, both F1 and F2 were intermediate. F2 population produced greater yields of seed cotton and lint cotton with heavier bolls and higher lint% as compared to the ELS parent. Whereas, fiber properties for F2 were not improved over the ELS parent. With regard to the induced variability, F2 population showed the wider ranges of distribution, higher variance and higher C.Vs as compared with the parents for all traits in the two crosses reflecting the efficiency of artificial hybridization in inducing variability in the studied genotypes. Cross II gave higher variance and C.Vs than cross I for most traits indicating that the introgressed variety Suvin induce more variability when it crossed with the Egyptian variety than the cross between the two Egyptian varieties. Broad-sense heritability (h2b) was high for fiber traits
than yield and its component traits traits. High h2b values were recorded for fiber length
in both crosses; moderate values were recorded for lint%; fiber fineness; strength and
uniformity. Low values were observed for boll weight, seed index seed cotton and lint yields. Mid-parent heterosis in F1 populations was low for most traits. Inbreeding depression % showed positive values for most of the studied traits. All traits in both crosses showed partial dominance, the direction was toward the higher parent for most traits. Neither of the F2 populations in both crosses exceeded the high parental mean for any economical trait (lint yield and fiber quality) although some of F2 individual plants gave higher yield and/or fiber quality than the parents. The value of these populations likely will be derived from the selected individual plants to be used in a pedigreed breeding program.

This study was carried out at Sakha Experimental Station, Agricultural Research Center during three seasons 2014, 2015 and 2016. The study aimed to evaluate the induced variability in some quantitative characters of the Egyptian cotton genotypes using hybridization and/or the chemical mutagen (Di-Methyl-Sulphat) and to estimate some genetic parameters that clarify the inheritance of yield and its components as well as fiber quality of two cotton crosses. The results indicated that the mutagen treatment decreased the mean performance for most of the studied traitsand increased the variability for all traits in the two crosses. Hybridization increased variability in both of F2 and F3 untreated populations as compared with parents for most of the studied traits which reflects the effectiveness of hybridization in inducing variability in the studied materials. Moreover, crossing the mutagen treated parents increased variability than crossing alone. Heritability estimates showed relatively moderate values (exceeded 30%) for the traits boll weight; micronaire reading and fiber length while the other traits showed relatively low values. The expected genetic advance upon selection in F2 gave high values for the traits boll weight, lint yield, micronaire reading and fiber length in both treatments. Potence ratio revealed partial dominance for most of the studied traits. Both additive(d) and dominance(h) parameters were significant for the traits, boll weight, seed cotton yield and lint yield indicating that both additive and non-additive effects were important in the inheritance of these traits. The epistatic effects, additive x additive(i) and dominance x dominance(l) were significant for yield and its component traits in both crosses and both treatments indicating the important role of these interactions in the inheritance of such traits, whereas fiber quality traits showed insignificant
values epistatic effects.

Field work and experiments were conducted at Shandaweel Experimental Station at Souhag Governorate, during 2013-2016 seasons. In 2013 season sixty type plants were selected from the breeding nursery of Giza 90 cotton cultivar that produced sixty progenies (increase A) in 2014. From the latter, 17 families were selected to form (increase B) in 2015, eight elite families were selected and their seed were massed carefully together to form the nucleolus (Breeder's seed) in 2016 season. The results obtained here indicated that, the pure line method in the sense of pedigree selection for annually renewing Giza 90 breeder's seed could prevent genetic contamination. Meanwhile, the selection technique for producing breeder’s seed of Giza 90 cultivar was valid and proved to be effective in holding the true type of the variety.

Agronomic and seed chemical characters of cottonseed play a prime role in seedling vigor establishment for cotton plant to obtain the maximum stand and better growth. Nutritional components in the seed play a very important role in early seedling developmental stage to produce healthy plants. The present study was conducted to investigate the genetic variability and relationship among agronomic, chemical components and seedling vigor characters of eight Egyptian cotton varieties (Gossypium barbadense) classified into two categories according to their fiber quality properties (long and extra long staple). The results showed highly significant genotypic variation for all the studied characters, which reflect the genotypic variability between the studied genotypes. Broad sense heritability ranged from moderate to high values for all the studied characters. Genetic divergence (D 2 ) showed highly significant dissimilarity between the two categories of Egyptian cotton varieties, except between the extra-long staple category. There was a highly significant and positive association between protein content and seed volume, lint index and seed index, also between oil content and carbohydrate content (0.583). While, seed oil percentage was not correlated with seed properties except lint percentage and a highly significant and negative correlation between seed protein and oil content. Most of the studied characters showed highly significant dissimilarity coefficients between and within these studied characters, which reflect the genetic variation background of these genotypes. Significant positive correlation and dissimilarity coefficients among and within these studied characters suggest that selection may be useful for the enhancement of the correlated characters.

The new promising cross [G83 × (G75 × 5844)] × G80 was produced by the Cotton Breeding Research Department of Cotton Research Institute from a cross between genotype G80 and [G83 × (G75 × 5844)] via artificial hybridization followed by the Pedigree method of selection. This promising cross belong to long staple category with boll weight 3.0 g, lint percentage 39.8 %, fiber length 29.7 mm, Micronaire reading 4.1 unit, and yarn strength 2157 unit. This promising cross characterized by high yielding and out yielded Giza 80 by about 20 and 21 % in seed cotton yield and lint cotton yield, respectively. This promising cross is characterized by its resistance against Fusarium Oxysporum. Thus, the promising cross [G83 × (G75 × 5844)] × G80 could be the best alternative to Giza 80