الفهرس 
INTRODUCTION
Description of the base populations; season of 2010Only 14 pages are availabe for public view
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Abstract
The present study was carried out at Arab El-Awamer, Agric. Res. Stn. Oil crops devision, Assiut, during the three summer seasons of 2010, 2011 and 2012. The soil type is sandy calcareous. The study aimed to improve earliness and seed yield in two segregating populations of sesame (Sesamum indicum L.). The genetic materials were the F2, F3 and F4-generations of two populations. The first population stemmed from the cross Shandaweel 3/Introduction 688. The second population was from the cross Sohag 2000/ Introduction 562. Two cycles of pedigree selection were achieved for four single traits i.e., days to first flower, height to first capsule, number of capsules /plant and seed yield/plant. The results could be summarized as follows:
1. Description of the base populations, season 2010
1.1 Days to first flower
In the F2-generations days to first flower in pop.1 ranged from 47.0 to 94.0 with an average of 70.82 days which fell outside the range of the two parents with phenotypic coefficient of variability of 14.37%, heritability in broad sense of 96.0% and expected genetic advance of 28.53% of the mean. Days to first flower in pop. 2 ranged from 44.0 to 104.0 with an average of 72.73 which fell outside of the parents, and coefficient of variability of 14.66%, heritability in broad sense of 0.92 and expected genetic advance of 27.81% of the mean.
1.2 Plant height
The F2-plants in pop. 1 ranged in plant height from 115.00 to 265.0 with an average of 200.99 cm which was higher than the taller parent by about 20 cm indicating dominance towards tallness. The coefficient of variability, heritability in broad sense and expected genetic advance from the mean were 13.45, 94.31 and 26.13%, respectively. In pop. 2 plant height ranged from 165.0 to 265.0 with an average of 210.49 cm. The maximum height of the two parents was 217.0 cm. The coefficient of variability, heritability in broad sense and expected genetic advance from the mean were 8.88, 82.82 and 15.15% of the mean.
1.3 Height to first capsule
The F2- plants in pop. 1 ranged in height to first capsule from 35 to 120 with an average of 57.67 cm which fell outside the range of the two parents. Also, in population 2 height to first capsule ranged from 30.0 to 75.00 with an average of 48.10 cm. The phenotypic coefficients of variability, heritability in broad sense and expected genetic advance were 22.48 and 18.06%, 85.13 and 75.46%, and 39.43 and 27.96% of the mean in population1 and population 2, respectively.
1.4 Length of fruiting zone
Length of fruiting zone of the F2-plants in pop. 1 ranged from 35.0 to 215.0 with an average of 143.31 cm, and ranged in pop. 2 from 120.0 to 215.0 with an average of 162.4 cm. The phenotypic coefficients variability, heritability estimates in broad sense and expected genetic advance were 24.46% and 11.75 %, 0.91 and 0.86, and 45.87 and 20.70 % of the mean for population 1 and population 2, respectively.
1.5 Number of capsules/plant
The F2- plants ranged in number of capsules/plant in pop. 1 from 85.0 to 291.0 with an average of 147.26, and ranged in pop. 2 from 70.0 to 379.0 with an average of 150.47. The coefficient of variability, heritability in broad sense and expected genetic advance were 28.55 and 36.92%, o.92 and 0.93, and 54.38 and 71.10% of the mean for population1 and population 2, respectively.
1.6 Capsule length
The F2- plants in pop. 1 varied in capsule length from 3.5 to 5.5 with an average of 4.51cm, and varied in pop. 2 from 3.5 to 5.5 with an average of 4.61 cm. The coefficient of variation, heritability and expected genetic advance were 9.09 and 9.05%, 0.55 and 0.58, and 10.37 and 10.63 % of the mean for population1 and population 2, respectively.
1.7 Capsule width
The F2-plants in pop. 1 ranged in capsule width from 0.80 to 1.40 with an average of 1.21 cm and ranged in pop. 2 from 0.90 to 1.50 with an average of 1.33 cm. The coefficient of variability, heritability in broad sense and expected genetic advance were 11.18 and 10.43%, 0.46 and 0.58, and 10.49 and 12.78 % of the mean for population1 and population 2, respectively.
1.8 Seed yield/plant
The F2-plants in pop. 1 ranged in seed yield/plant from 6.02 to 19.02 with an average of 12.46 g, and in pop. 2 ranged from 5.12 to 19.86 with an average of 13.61 g. The coefficient of variability, heritability in broad sense and expected genetic advance were 18.70 and 15.80 %, 0.65 and 0.45, and 24.95 and 14.76% of the mean for population 1 and population 2, respectively.
2. Phenotypic correlations in the base populations
2.1 Days to first flower showed negative significant (p<0.01) correlations with plant height, height to first capsule, length of fruiting zone and number of capsules/plant in the two populations.
2.2 Plant height showed negative significant (p<0.01) correlation with height to first capsule in pop. 1, and positive in pop. 2. Plant height was positively correlated (p<0.01) with each of length of fruiting zone and capsule length in both populations. Also, it showed positive significant (p<0.05) with seed yield/plant (0.124) in pop. 2, and insignificant in pop. 1 (0.082).
2.3 Height to first capsule showed contradictory correlations with the other traits in the two populations; it gave negative (p<0.01) correlation with length of fruiting zone, positive with number of capsules/plant (0.234 ”p<0.01”) in pop. 1 and negative (-0.023) insignificant in pop. 2. Height to first capsule gave negative insignificant correlation with seed yield/plant in pop. 1 (-0.063) and positive significant (0.139) in pop. 2. The results of correlations among the studied traits indicated different gene associations between traits in the two populations.
3. Pedigree selection for days to first flower
3.1 Mean squares after two cycles of pedigree selection for days to first flower and the other correlated traits were significant in both populations, except capsule length in pop. 2.
3.2 After two cycles of selection the genotypic and phenotypic coefficients of variability of the selected families were rapidly depleted and accounted for 1.93 and 2.08% in pop. 1, and 5.05 and 5.19% in pop. 2, respectively. These results indicate great depletion of genetic variability in the two populations, and further cycles of selection for days to first flower will not be fruitful. In addition; selection for earliness could be practiced in the early segregating generations.
3.3 Heritability estimates
Heritability estimates in broad sense for days to first flower in the F4- generation were 86.48% for pop. 1 and 94.72% for pop. 2.
3.4 The direct observed gain in the selection criterion
The average direct gain in days to first flower in pop. 1 in the first cycle was -38.35 and after two cycles was -35.31% from the bulk sample, while, the respective gains from the better parent were -30.20 and -34.06%. In pop. 2, the direct gains were -30.37 and -37.18% from the bulk sample, and -15.42 and -9.75% from the earlier parent after one and two cycles of selection, respectively. These results indicate that the possibility of selection for days to first flower in the early generations, and two cycles of selection were enough to detect the earliest families in these populations.
3.5 The correlated gains in population 1
The correlated gains in the other traits in pop. 1 showed significant (p<0.01) improvement in plant height (21.62%), length of fruiting zone (37.07%) and seed yield /plant (24.77%) , while it was negative for height to first capsule (-8.88%) and number of capsules/plant of -10.82% from the bulk sample. The average correlated gain from the better parent was significant (p<0.01) only for plant height (12.50%), height to first capsule (-21.19%) and length of fruiting zone (31.79%).
3.6 The correlated gains in population 2
After two cycles pedigree selection for days to first flower, there were significant (p<0.01) increase in plant height (5.53%), increase in length of fruiting zone (12.89%), increase in capsule length (13.03%), significant (p<0.05) increase in seed yield/plant of 22.24%, and insignificant decrease in height to first capsule (-14.85%), from the bulk sample. While, the average correlated gains measured from the better parent showed significant (p<0.01) decrease in height to first capsule (-32.27%), increase in length of fruiting zone (14.06%) significant (p<0.05) decrease in plant height (-3.62%) and capsule width (-4.36%). Otherwise, the gains were not significant for the other traits.
4. Pedigree selection for height to first capsule
4.1 Mean squares of the selected families along with the parents and the unselected bulk sample were significant (p<0.01) for all traits in both populations.
4.2 The pcv and gcv % in population 1 as calculated from the analysis of variance of the ten selected families in the F4–generation could be considered zero for height to first capsule because insignificant mean squares . However, they were high in pop. 2 and reached 22.46 and 26.95 % for gcv and pcv, respectively.
4.3 Heritability estimates
Heritability estimates in broad sense for height to first capsule was not significant in pop. 1, while, it was 69.42% in pop. 2 in the F4 –generation.
4.4 The direct observed gain in the selection criterion
The average direct gains in height to first capsule were -66.11 and -49.49 % from the bulk sample, and -82.59 and -56.71% from the better parent after cycle 1 and cycle 2, respectively. Respect to pop. 2 the average direct gains were -57.04 and -44.90 % from the bulk sample and -14.07 and -56.17% of the better parent after cycle 1 and cycle 2, respectively.
4.5 The correlated gains in population 1
The average of the selected families indicated significant (p<0.01) correlated gain reached -13.14, -7.57, 47.92 and -11.37 % from the bulk sample for plant height, number of capsules/plant, seed yield/plant and days to first flower. The average correlated gains of the other traits were not significant. The average correlated gains from the better parent were significant (p<0.01) for plant height (-19.65%), capsule length (11.11%), seed yield/plant (34.81%) and days to first flower (-18.38%). Three superior families; no. 5, no. 121 and no 154 showed significant (p<0.01) observed gain in seed yield/plant of 34.81, 16.92 and 70.92% from the better parent, respectively.
4.6 The correlated gains in population 2
The average correlated gains from the bulk sample were significant (p<0.01) for length of fruiting zone (7.58%), capsule width (7.27%), seed yield/plant (27.59%), and days to first flower (-17.71%). However, the average correlated gain from the better parent was significant (p<0.01) for plant height (-12.22%), length of fruiting zone (10.94%), Capsule width (-.9.23%) and days to first flower (18.23%). Two superior families; no.38 and no.81 showed significant gain (p<0.01) in seed yield/plant of 24.89 and 29.45%, respectively, from the better parent. selection for height to first capsule caused earliness in pop. 1 and delayed flowering in pop. 2 as measured from the earlier parent, which indicates different gene associations in the two populations. It could be concluded that pedigree selection was efficient to improve height to first capsule in the two populations in the early generations, but, it showed adverse effects on plant height and number of capsules/plant.
5. Pedigree selection for number of capsules/plant
5.1 The entries mean squares in the F4-generation for all traits were significant in both populations, except for capsule width in pop. 1 and capsule length in pop. 2.
5.2 The phenotypic and genotypic coefficients of variability of number of capsules/plant after two cycles of selection tended to be moderate in both populations. The pcv% decreased from 28.55 in the F2-generation to 7.56% after two cycles of selection pop. 1, and from 36.92 to 5.78% in pop. 2.
5.3 Heritability estimates
Broad sense heritabilities of number of capsules/plant were 80.50% in pop. 1 and 95.62% in pop. 2.
5.4 The direct observed gain in the selection criterion
The average direct observed gains in number of capsules/plant in pop. 1 were 57.13 and 33.71% from the bulk sample, and were 21.55 and 43.21% from the better parent for cycle 1 and cycle2 in pop. 2, respectively. These results indicate to the efficiency of pedigree selection to improve number of capsules/plant.
5.5 The correlated gains in population 1
Two cycles of selection for number of capsules/plant adversely affected length of fruiting zone. However, favorable gains in days to first flower were obtained and reached -21.61 and -28.09%,from the bulk sample and the better parent, respectively. Seed yield/plant showed significant gain of 52.97% from the bulk sample, but, such increase was not significant from the better parent. However, three families; no.84, no.284 and no.337 showed significant gains in seed yield/plant from the better parent.
5.6 The correlated gains in population 2
Significant gains were obtained and accounted for 12.95 and 3.54% for plant height, 27.73 and 29.06% for length of fruiting zone, and -32.28 and -46.13% for height to first capsule from the bulk sample and the better parent, respectively. The correlated gain in seed yield/plant (31.40%) was significant from the bulk sample, and insignificant from the better parent. Also, days to first flower showed significant correlated gain from the bulk sample of -17.0%, while, it showed significant delay in flowering of 19.24% from the earlier parent.
6. Pedigree selection for seed yield/plant
6.1 Mean squares of the entries for all traits after two cycles of selection for seed yield/plant were significant (p<0.01) in both populations except for capsule width in pop. 1.
6.2 The phenotypic and genotypic coefficients of variation of the selection criterion were high in pop. 1; 14.70 and 14.35% and tended to be moderate; 11.22 and 8.58 % in pop. 2, respectively.
6.3 Heritability estimates
Heritability in broad sense estimates of seed yield/plant were 95.37 and 76.47% for pop. 1 and pop. 2, respectively
6.4 The direct observed gain in selection criterion
The direct gain in seed yield /plant in pop. 1 increased from 53.75 to 99.49% of the bulk sample, and from 16.39 to 30.66% of the better parent for cycle 1 and cycle2, respectively. Likewise, in pop. 2 the direct gain increased from 25.75 for cycle1 to 74.40% after cycle 2 from the bulk sample, and from 18.79 to 45.18% from the better parent for cycle 1 and cycle 2, respectively. The retained genetic variability after the two cycles of selection was sufficient for further cycles of selection.
6.5 The correlated gains in population1
Two cycles of selection for seed yield/plant accompanied with significant (p<0.01) correlated gains of 23.23 and13.99% for plant height, -12.78 and -13.99% for height to first capsule, 20.53 and 15.90% for length of fruiting zone, 9.16 and 16.92% for number of capsules/plant and -10.43 and -8.70% for days to first flower from the bulk sample and the better parent, respectively. Several superior families; no.5, no.84, no.226 and no. 238 were superior in seed yield, number of capsules/plant and significant (p <0.01) earlier than the earlier parent.
6.6 The correlated gains in population 2
Pedigree selection for seed yield/plant in pop. 2 accompanied with favorable significant (p <0.01) correlated gains in height to first capsule of -24.28 and -39.77% , 13.92 and 15.10% for length of fruiting zone, and 54.72 and 49.46 % from the bulk sample and the better parent, respectively. However, adverse significant (p <0.01) effects in plant height of -4.86% and in days to first flower of 11.96% of the better parent. It could be concluded that pedigree selection was efficient to improve the selection criterion, but, it cause adverse effects on some other traits. For example, selection for seed yield/plant in pop. 2 delayed flowering and cause significant adverse effects on plant height.