الفهرس 
Gene action
Establishment of inter-lines crossesOnly 14 pages are availabe for public view
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Abstract
This study was carried out at the experimental farm of Faculty of Agriculture, El-Kawther, Sohag University, Egypt. The genetic material used in the present investigation consisted of nine parental Lines and the S.C.10 was used as a control. The nine parental Lines were divided into four “fathers” which were crossed with five “mothers” so as to yield 20 crosses in North Carolina Design II fashion.
By estimates heterosis values over mid-parents for crosses the results showed highly significant for all studied traits under irrigated and drought conditions.
The analysis of variance revealed highly significant differences between the genotypes under both environments.
1- Days to pollen shedding:
The estimates of genetic parameters for number of days to pollen shedding showed important role of dominance genetic variance (σ2D) under the irrigated and drought conditions than those of additive ones (σ2A). Narrow sense heritability was reached to 0.12 under irrigated conditions. While, it was reduced to 0.08 under drought stress.
2- Plant height:
The estimates of the genetic parameters revealed that the main genetic component under the irrigated conditions was additive (σ2A) which was larger than the dominance components (σ2D). The narrow sense heritability reached 0.80.
3- Biomass:
Estimates of genetic parameters showed that (σ2D) was larger than (σ2A) under irrigated condition. However, under drought stress (σ2D) was also slightly greater than (σ2A). Under irrigated conditions, narrow sense heritability amounted to 0.24. Heritability in the narrow sense was increased under drought to 0.64.
4- Grain Weight:
Estimates of the genetic parameters under irrigated conditions indicated that the (σ2A) was larger than the (σ2D). Whereas, the (σ2D) was relatively slightly larger than (σ2A) one under drought conditions. The narrow-sense heritability was high which reached to 0.91, while, it was reduced to 0.55 under drought conditions.
A. Drought susceptibility index:
Drought susceptibility index indicated that genotypes A3, B8, C12, C16 and crosses (A3 x B5) and (A3 x C1) showed ”S” values less than one revealing relative drought resistance.
B. Harvest index:
The results of harvest index of line B3 displayed outstanding harvest index which exceeded 22% and was less than that of the check S.C.10 under irrigated conditions. Under drought conditions, the parental line B3 displayed the better harvest index. Ten crosses showed relative high harvest indices under irrigated conditions. Meanwhile, six crosses showed outstanding harvest index under drought stress.
5- Ear weight:
The genetic parameters under the irrigated conditions indicated that this trait was mainly controlled by (σ2A) which was larger than (σ2D) one. Whereas, (σ2D) was greater than in magnitude that the (σ2A) under drought stress. The narrow sense heritability amounted to 0.63 under the irrigated conditions while. It was reduced to 0.43 under drought.
6- Ear diameter:
The estimate of the genetic parameters indicated that the major genetic component under the irrigated conditions was (σ2D) which was larger than the (σ2A) one. However, under drought stress, the (σ2A) was greater than that (σ2D) in magnitude. Heritability in the narrow sense was 0.54 under drought stress. Narrow sense heritability amounted to 0.21 under the irrigated conditions.
7- Ear length:
The obtained estimates of the genetic parameters revealed that the main genetic component under the irrigated conditions was (σ2D) which was larger than the (σ2A) component. Under drought stress, the relative size of the (σ2D) equaled to that of the (σ2A) component. The narrow sense heritability amounted to 0.17 irrigated conditions and it was increased to 0.50 under stress.
8- Number of rows:
The estimates of genetic parameters indicated that the (σ2A) was slightly larger than the (σ2D) under the irrigated conditions. Whereas, the (σ2D) was very larger than the (σ2A) under drought stress. The narrow sense heritability amounted to 0.32 under irrigated conditions and it was reduced to 0.11 under drought stress.
Molecular analysis of RAPD markers:
A total of 62 fragments were generated by 7 primers. The number of amplification bands by each primer varied from 5 to 13 these fragments are in a range of 100 to 943 base pairs. A total of 48 bands were polymorphic across the entire samples were observed with an average of 77.14 %. The values of similarity reached from 0.77 to 0.92 between B3 line with S.C.10 and B10, respectively. Lines B3, B5 and C1 clustered with B10, C12 and C15, respectively, at 0.92 similarity level. The S.C.10 showed level of similarity matrix from 0.77 to 0.89 with (B3 and B12), and B8, respectively.
Phylogenetic trees:
The dendrograms based on RAPD technique and means of morphological characters showed a high genetic similarity between the S.C.10 and the 9-parental lines. The check S.C.10 and A3 line were found isolated in the both dendrograms. The C1 and C10 were associated with high genetic similarity coefficient (96.6%) based on means of characters, and C1 associated with C15 based on the RAPD marker at similarity percent of (92%). Also, The Egyptian lines B3 and B10 were associated with high genetic similarity coefficient (94%) based on means of characters.