الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The flax crop is the second most important fiber crop in Egypt. The cultivated area during the 2019/2020 agricultural season is about 21,386 acres, producing about 7525 tons of fiber and 10,000 tons of seed crop (FAO, 2021). In view of the climatic changes that have occurred in recent years and the shortage of water, this study was conducted with the aim of valuating some genetic structures of flax plants to determine the extent of their response to water shortages. This study was conducted at the research farm of the Crops Department - Faculty of Agriculture - Mansoura University - Egypt during the 2018/2019 and 2019/2020 seasons using six flax genotypes as parents that were planted in the first agricultural season and all possible crosses between them were made through the semicircular mating system to obtain Fifteen hybrids. All the resulting hybrids were evaluated, in addition to the parents, to determine their response to water shortage and determine the best. In the implementation of these experiments, a randomized complete block design was used in three replicates. The readings and measurements taken on individual plants included the following characteristics: 1- Early characteristics: number of days to flowering (day) - number of days to maturity (day). 2- Growth characteristics: plant height at the beginning of flowering (cm) - plant height at harvest (cm) - crown area diameter (mm) - stem diameter (mm) - capsule diameter (mm) - effective length (cm). 3- Crop characteristics and components: number of basal branches - number of apical branches - number of capsules in apical branches - number of seeds per capsule - number of plant capsules - length of the fruiting zone (cm) - 1000 - seed (g) - seed yield per plant (gm) - yield straw (g) - biological yield (g) - fiber yield (g). 4- Quality and chemical characteristics: length of fiber (cm) - percentage of fibers % - oil % - iodine number - percentage of cellulose % - hemicellulose % - percentage of lignin % - percentage of cellulose ⁄ lignin %. The normal statistical analysis of the studied traits was carried out using the randomized complete block design in three decisions, then the genetic statistical analysis was conducted to calculate the general and specific ability to combine using the fourth method (one-way crosses without parents) the first model of the world Griffin 1956.The results of this study can be summarized as follows: Variance analysis: The mean squares of deviations of the genotypes for all the traits under study were highly significant for irrigation and drought factor except for the number of days to flowering, plant length at the beginning of flowering, length of the fruiting area, number of capsules per plant, number of seeds per capsule, 1000 - seed weight, and percentage of fiber. As for the genotypes, the mean squares of deviations were highly significant for all the traits under study, except for the trait of the number of basal off shoots. As for the interaction between the two factors of the study, the mean of the squares of deviations was highly significant for all the traits under study except for the trait of the number of basal branches and the number of seeds per capsule. Average behavior of the studied hybrids under irrigation and water stress conditions: The results under study showed that there were significant differences between irrigation and drought treatments on the trait of number of days to maturity, and there were no significant differences between treatments on the trait of number of days until flowering. The results also showed that there were significant differences for irrigation and drought treatments on growth characteristics, yield and its components, where the results showed significant differences on most of the traits under study except for the length of the plant of the beginning of flowering, stem diameter, number of seeds per capsule, number of capsules per plant, length of the fruiting zone, 1000 - seed weight. The results also showed that there were significant differences on all the quality and chemical traits, except for the proportion of fibers. The genotypes showed significant differences between them on the characteristics of early growth, growth, yield and its components, as well as quality and chemical characteristics. Regarding the parents: the results showed the superiority of P2 over the rest of the parents under study in the characteristics of plant height of flowering, 1000 - seed weight, fiber yield, fiber length and fiber percentage under normal irrigation conditions, while P4 progressed the rest of the parents in the characteristics of crown area diameter, stem diameter, The number of capsules of apical branches, length of the fruiting zone, straw yield, and hemicellulose percentage under normal irrigation conditions, while P5 was superior in the characteristics of number of days to maturity, number of basal branches, number of capsules per plant, and biological yield under normal irrigation conditions. As for P6 it progressed the rest of the parents in the characteristics of the number of seeds per capsule, the seed yield of the plant under normal irrigation conditions, the proportion of lignin, the length of the plant at harvest, the effective length, and the number of basal branches under drought conditions. P3 was superior in the proportion of cellulose, and the ratio between cellulose and lignin under irrigation conditions, while P1 was superior in the proportion of oil compared to some parents under irrigation conditions.As for the hybrids: Hybrid P1xP5 progressed in the trait of the diameter of the crown area under irrigation conditions and in the trait of the weight of a thousand grains and the diameter of the capsule under drought conditions, while the hybrid P1xP4 progressed in the trait of the number of capsules in the apical branches. The hybrid P1xP3 progressed in the trait of the number of basal branches under irrigation conditions and % of the embryo under drought conditions. The results also showed the superiority of the hybrid P2xP6 in the trait of the biological crop under irrigation conditions, while the hybrid P2ˣP5 progressed the rest of the hybrids in the trait of plant height at the beginning of flowering and plant height at maturity under irrigation conditions. The results also showed the superiority of the hybrid P2xP4 in the trait of the number of days to maturity under drought conditions and in the trait of % of oil and iodine number under irrigation conditions. While the hybrid P3xP5 was superior in stem diameter, fiber yield, fiber percentage and % of cellulose/lignine under irrigation conditions and number of days to maturity under drought conditions. While the hybrid P4xP5 was superior in the effective length and straw yield under irrigation conditions than the rest of the hybrids. The results also showed the superiority of the hybrid P3xP6 in the trait of the number of apical branches under drought conditions and in the trait of length of fiber and % of hemicellulose under irrigation conditions. While the hybrid P4xP5 progressed in the length of the fruiting zone under drought conditions and the hybrid P4 x P6 in the seed yield of the plant under drought conditions. While the P3xP4 hybrid was superior to % cellulose. Combining ability: The analysis of the general and specific combining abilities showed high significance in all the traits under study, which shows the relative importance of both the host and non-host influences of genes in the inheritance of these traits. 1- The mean of squares of the general ability to combine was significant or very significant for all the traits under study except for the number of days to maturity, effective length, stem diameter, number of capsules of apical branches, length of fiber under drought conditions, characteristics of number of basal branches, number of apical branches, and number of apical branches. The capsules for the apical branches, the length of the fiber under drought conditions, the characteristics of the number of basal branches, the number of apical branches, and the number of capsules for the apical branches under irrigation conditions. As for the special ability to combine, the averages of squares were significant or very significant for most of the traits under study except for the number of days to maturity, the number of basal branches, the number of seeds in the capsule under drought conditions, and for the number of basal branches under irrigation conditions. 2- The ratio between the variance of the general and specific ability to combine (GCA/SCA) under irrigation and drought conditions recorded values higher than one for a number of traits, including the number of days to maturity, plant at harvest, stem diameter, capsule diameter, length of the fruiting zone, number of basal branches, number of apical branches, length of fiber, and lignin under irrigation conditions. Oil percentage, number of seeds in capsule, fiber yield, number of days until the beginning of flowering under drought conditions, characteristics of crown area diameter, biological yield, weight of one thousand grains. Which shows that the additional genetic act controls the inheritance of these traits, while the rest of the traits recorded a percentage less than the correct one, which shows that the extra genetic act controls the inheritance of these traits .3- Some parents showed a high general ability to combine for some traits under irrigation and drought conditions, and thus they can be used as parents in crosses and selection in the resulting isolates to improve these traits were as follows: P1 recorded a general ability to combine in improving the characteristic of the number of days to flowering and the number of days to maturity under irrigation and drought conditions and the number of seeds per capsule % , and lignin % under drought conditions, while P3 recorded a general ability to combine to improve the characteristics of plant height at harvest, short stem and length of the fruiting zone. The length of the fiber, % oil and straw yield, % of cellulose, and the ratio between cellulose and lignin under irrigation conditions, as well as for the character of capsule diameter under drought conditions. P4 recorded a general ability to combine to improve the characteristics of plant height at the beginning of flowering, iodine number under irrigation conditions, characteristics of plant height at harvest, biological yield, number of basal branches, length of the fruiting area, % oil, % cellulose / lignin under drought conditions, as for P5, it was recorded A general ability to combine to improve the characteristics of crown diameter, biological yield, capsule diameter, seed yield per plant, number of capsules per plant, 1000 - seed weight, percentage of fibers, fiber yield, % hemicellulose and % lignin under irrigation conditions. The results showed that P5 had a general ability to synthesize to improve the properties of fiber length and % hemicellulose under drought conditions. The results showed that P6 had a general ability to combine to improve the characteristics of effective length under irrigation conditions, characteristics of the number of apical branches, number of capsules per plant, iodine number and % of cellulose under drought conditions. 4- The results of the effects of the special ability to harmonize showed that there were significant differences for some of the crosses under study. The results showed that there were differences between the hybrids with regard to the traits under study, where the hybrid P3xP5 showed a special ability to combine with regard to the characteristics of fiber yield of the plant, straw yield, % fiber, seed yield of the plant, and the number of capsules of the apical branches under irrigation conditions. While the hybrid P2 x P4 showed a special ability to combine for the two traits: number of days to flowering, number of days to harvest and iodine number under irrigation and drought conditions, as well as % of oil under drought conditions. Hybrid vigor: The results indicated, based on the estimates of hybrid vigor, that the best of the earliest hybrids for the number of days until flowering at average and the best parents were hybrid No. 11 under normal irrigation conditions and hybrid No. 7 under drought conditions. Regarding the number of days to maturity, the best crosses were hybrid No. 6 for the average parents and hybrid No. 11 for the best parents under drought conditions. Regarding plant height at the beginning of flowering, the best hybrids were No. 10, No. 14 and No. 8. For the average parents under irrigation conditions, hybrid No. 8 and hybrid No. 10 under drought conditions were for the best parents. As for the plant height at harvest, the best hybrids No. 2 and No. 8 were for the average and the best parents under irrigation conditions. As for the effective length, the best hybrids No. 13 and No. 7 were for medium and best parents under irrigation conditions. As for the number of apical branches, the best hybrids No. 14 and 10 were under irrigation conditions, and hybrid No. 4 and 10 under drought conditions for the average and best parents. Regarding the number of capsules for the apical branches, the best hybrids No. 1 were for the average and best parents under irrigation conditions and the best hybrids No. 3 under the dry conditions for the average and best parents. Regarding the number of capsules per plant, the best hybrids were No. 12 for the average and best parents under irrigation conditions, and Hybrid No. 2 under the dry conditions for the average and best parents. Regarding the length of the fruiting zone, the best hybrids No. 12 were for the average and the best parents under irrigation conditions, and the best hybrids No. 13 under the dry conditions for the average and best parents. For 1000 - seed weight, the best hybrids No. 4 and 5 were for medium and best parents under irrigation conditions, and hybrid No. 13 under drought conditions for average and best parents. Regarding the number of capsules per plant, the best hybrids were No. 12 for the average and best parents under irrigation conditions, and Hybrid No. 2 under the dry conditions for the average and best parents. As for the seed yield of the plant, the best hybrids No. 2 were for medium and best parents under irrigation conditions, and hybrid No. 5 under drought conditions for the average and best parents. As for the fiber yield, the best hybrids were No. 14 under medium and best parents under irrigation conditions, and hybrid No. 1 under drought conditions for the average and best parents. Regarding fiber length, the best hybrids No. 4 and No. 8 were for medium and best parents under irrigation conditions, and hybrid No. 10 under drought conditions for average and best parents. As for fiber, the best hybrids No. 6 and 11 were for the average and best parents under irrigation conditions, and hybrid No. 4 under the drought conditions for the average and best parents. As oil %, the best hybrids No. 12 and No. 7 were for medium and best parents under irrigation conditions, and hybrid No. 7 under drought conditions for average and best parents. Regarding the iodine number, the best hybrids were No. 7 for the average and the best parents under irrigation and drought conditions. Regarding cellulose%, the best hybrids were No. 7 for medium and best parents under irrigation conditions and hybrid No. 13 under drought conditions for average and best parents. For hemicellulose, the best hybrids No. 12 were for medium and best parents under irrigation and drought conditions. As for % lignin, the best hybrids No. 2 were for medium and best parents under irrigation and drought conditions. As for % of cellulose/lignin, the best hybrids No. 15 were for medium and best parents under irrigation conditions and hybrid No. 6 under drought conditions for average and best parents. Hertabiliy: The results showed that the estimates of heritability in the broad sense were high under irrigation and drought conditions for all traits under study. The genetic and phenotypic variance under drought conditions was higher than the genetic variance under normal irrigation conditions for the characteristics of plant height at flowering, plant height at harvest, effective length, number of apical branches, number of apical branches, number of seeds per capsule, seed yield, number of capsules per plant, length of the fruiting zone, 1000 - seed weight and oil yield. While the genetic and phenotypic variance under irrigation conditions was higher than the genetic and phenotypic variance under drought for the characteristics of the number of days to flowering, biological yield, fiber yield, straw yield, fiber length, fiber percentage, oil percentage, cellulose and hemicellulose percentage, and cellulose/lignin percentage. The percentage of heritability in the broad sense was higher under irrigation conditions than drought for most traits except for the characteristics of plant height at harvest, capsule diameter, number of basal branches, number of apical branches, number of seeds per capsule, seed yield per plant and number of capsules per plant. Conclusion P6 recorded a general ability to combine to improve the trait of seed yield, P1 for the fiber crop, P2 for the straw crop, and P4 for the biological crop under dry conditions, while the hybrid P1xP4 showed a special ability to combine for the seed crop, the hybrid P1xP5 for the biological crop, and the hybrid P1xP2 for the crop. fiber and hybrid P3xP5 for straw yield under drought conditions. The results also showed that the hybrid P1xP5 was the best hybrid for the medium and the best parents for the biological crop, the hybrid P1xP6 for the seed crop, the hybrid P1xP2 for the fiber crop, and the hybrid P3xP5 for the straw crop under drought conditions.