Biology
AgriculturalAndFoodSciences,1970-2015-Agricultural And Food Sciences-2013.jsonl.gz.gz
Agricultural And Food Sciences
2bca17c84504f066ab5d59aec6648b774894181b
Estimate of Genetic Parameters of Grain Yield and Some Agronomic Traits in Durum Wheat Using Diallel Crosses

Five varieties of durum wheat were crossed in full diallel fashion through 2010/2011 growing season. The five parents and their 20 F1 progenies were grown in 2011/2012 at the farm of faculty of agricultural and forestry, Duhok university, Iraq, using randomize complete block design with three replications to estimate heterosis, heritability and some genetic parameters for yield and its components. The results showed highly significant difference among genotypes for all studied traits. The parent Um Raby-5 had a positive general combining ability effect for most traits including grain yield. The crosses (Kokorete71  LD – 357E), (Crezo  Um Raby-5), (Cimeto  Um Raby-5), (Cimeto  crezo) and (Cimeto  Kokorete 71) exhibited significant desirable specific combining ability effect for most traits. The dominance was greater than additive almost traits. Heritability inbroad sense was high but heritability in narrow sense was low. The expected genetic advance as percent of traits mean was low for all traits. Most crosses showed significant positive heterosis for most traits and two crosses, (Crezo Cimeto) and (Cimeto Um Raby-5) had the highest positive heterosis for the most studied traits including grain yield.


Introduction
Durum wheat (Triticum durum Desf.) covers approximately 20 million hectares wordwide, which represents less than 10% of total wheat areas [1] in Iraq during 2003, the planted area by wheat about 1.85 million hectares that produced 2.553 million tons, but in Kurdistan region the planted area by wheat was about 670.989 thousand and production was 504.078 thousand tons. The percentage of durum wheat from this production was more than 50%.
Successful breeding program mainly depends on the variability of genetic variation [2]. However, utilization of genetic recourses as a source of variability requires their proper systematic evaluation [3]. Wheat breeder tends to use new strategies and techniques to predict the expected gain in the cultivar general combining parents. Some of studies reported significant additive gene effects, or GCA variances, and non additive gene effects, or SCA variances, Chowdhary [6] and Oettler [7] for most of economic traits in wheat, diallel mating design has been provided information regarding genetic mechanisms controlling grain yield and other traits [8].
Significant reciprocal effects in the expression of grain yield and other economically important traits have been reported by Chowdhary [6] in bread wheat and [13][14][15] in durum wheat. This indicates maternal influence in determining the phenotypes of F 1 and thus importance of selecting parents while making crosses. Also, there is evidence for expression of heterosis in grain yield and almost of agronomic traits in wheat [5].
The objective of this study was to estimate GCA and SCA effect for grain yield, and some agronomic traits among five genotypes complete diallel cross of durum wheat to appropriate parents and crosses for the investigated.

Materials and Methods
The experiment was carried out at the field of faculty of agriculture and forestry, university of Duhok. Five durum wheats comprised: Kokorete 71, LD-357E, Crezo, Cimeto and Um Raby-5 were used as parents in this study. These genotypes were planted 15/12/2010 in rows (3 m length and 1 m) wide, and full diallel cross among them was done and reciprocal F 1 to obtain F 1 seeds. The parents, F 1 and reciprocal crosses (25 genotypes) were evaluated using randomize complete block design with three replications. Each genotype (15 seeds) was grown in rows of 3 m length with 30 cm width and 20 cm plant to plant distance in each replication. The study was conducted on the same field during 2011-2012. The following traits were studied days to 50% flowering, plant height (cm), flag leaf area (cm 2 ), No. of spikes/plant, No. of grains/spike, 1,000-grain weight (g) and grain yield/plant (g).
The data were subjected to analysis of variance according to experimental design used and the differences between genotypes tested using DMRT [16]. The mean square of genotypes partitioned to GCA, SCA and reciprocal according to method of one [4], to estimate the effect of GCA for parents and SCA for F 1 crosses and reciprocals F I . Using expected mean square of GCA, SCA, reciprocal error, the components of variance additive, dominance total genetic and environmental were estimated, and then broad and narrow sense heritability were determined. Heterosis as departure of F 1 and reciprocal F 1 's from mid parents were estimated and its significant tested using t-test.

Results and Discussion
The analysis of variance results are given in Table 1 that revealed highly significant mean square of genotypes for all traits. The mean performance of parent, F 1 crosses and reciprocal F 1 crosses for different traits were presented in Table 2. Less number of days to 50% flowering observed in parent LD357E, Which took 137.25 days while parent Cimeto was the latest which had taken 155.87 days, the difference between parents reflected significantly on their crosses. was surpassed for days to 50% flowering and number of grains/spike and also the parent Crezo was surpassed for 1,000-grain weight then these parents could be used inbreeding program with other varieties to improve these traits. The cross Crezo × Cimeto was surpassed other from most traits (days to 50% flowering, plant height, 1,000-grain weight and grain yield/plant, while the cross UmRaby5 × Crezo gave high flag leaf area, and the cross Cimeto × UmRaby5 recorded the maximum number of spikes/plant, whereas the cross LD357E × Kokerete71 recorded the highest value of grains/spike, then these crosses could be used in selection program to improved varieties. The same results have been reported by other researchers like Tawfiq [17], Ali [18] and Rashidi [19]. Analysis of variance for general, specific combining ability and reciprocal is presented in Table  3. Mean square of GCA and SCA were highly significant for all traits indicating additive and non additive type of gene action involved in the manifestation of traits under study. Also, the mean square of reciprocal was highly significant for all studied traits indicating the maternal effect on the behavior of cross produced by reciprocal. The ration of GCA to SCA components was less than 1 for all studied traits, which revealed the more importance of dominance gene action in controlling these traits which could be improved through hybridization. These results are consistent with other researchers' results like Nazir [20], Hassan [21], Ammen [22], Mahpara [23] and Akram [24]. Table 4 showed, estimates of general, specific and reciprocal effect of parents, crosses for all studied traits. The parent Kokerete71 and LD357E gave negative effects of GCA for number of day to 50% flowering (-0.034, -1.802), respectively, which indicate the ability of these parents to reduce the number of days to 50% flowering, while the parents  For previous results, it was concluded that the crosses Kokerete71 × LD357E and Cimeto × UmRaby5 had significant desirable SCA for all studied traits, followed by Crezo × Cimeto which had significant desirable for all traits except number of days to 50% flowering and 1,000-grain weight. The results presented in Table 3 exhibited some crosses appeared high SCA from contrast parents from ability of GCA, for example, the parents Kokerete71 and LD357E appeared negative GCA for the most traits, but the cross produced from them, Kokerete71 × LD357E was recorded highest SCA for all traits and to the contrary, the cross Cimeto × UmRaby5, one of parent had high GCA for the most traits and other parent had negative SCA but cross produced highest SCA for all traits.
The data in Table 4 showed the estimation of reciprocal effect for crosses. The crosses UmRaby5 × Cimeto and Cimeto × Crezo showed positive reciprocal effect for all traits except, plant height and number of days to 50% flowering. The remaining of reciprocal crosses exploited positive or negative SCA for different traits. These results are in agreement with those reported by Farooq [25], Khan [8], Ameen [22] and Akram [24]. Table 5 presents variance components and some genetic parameters. It was shown that the dominance genetic variance was more than additive for all traits, indicating the preponderance of over dominance gene effect in the genetic control of these traits. The Table 4 Estimates of general and specific combining ability for parents, hybrids and reciprocal.

Genotypes
Days to 50% flowering value of environmental variance was low for all traits. The value of the average degree of dominance was more than one for all traits, indicating the presence of over dominance. Heritability in broad sense was high for all traits, while narrow sense heritability was low for all traits and ranged from 2.37% for number of days to 50% flowering and 21.02 for number of grains/spike. Expected genetic advance as percent of traits means was ranged from 0.01% for days to 50% flowering and 0.64% for number of grains/spike and it was low for all traits. These results are in agreement with some earlier findings [13,17,22,[26][27][28].
Heterosis for all traits as departure traits as departure of F1 from mid parents was presented in Table 6. Negative heterosis was observed in crosses (Crezo × Cimeto, Crezo × UmRaby5, Cimeto × UmRaby5, UmRaby5 × Cimeto, Cimeto × Crezo, Crezo × LD357E, Crezo × Kokerete71, LD357E × Kokerete71) for days to 50% flowering, while the remaining crosses gave positive heterosis (in non desirable direction) for this trait. For plant height, the crosses (Kokerete71 × LD357E, LD357E × Cimeto, Crezo × Cimeto, Cimeto × UmRaby5, UmRaby5 ×Crezo, Cimeto × Crezo, Cimeto × LD357E, Crezo ×   Table 6 indicated that 33% of crosses gave positive effect over their mid parents. The range of heterosis effect for grains/spike was from 0.93 UmRaby5 × Cimeto to 25.65% Crezo × Cimeto. Out of 20 crosses, eight had highly significant heterosis, seven had negative significant and five had non significant heterosis. The highest value of heterosis was 25.65% exhibited by cross Crezo × Cimeto, followed by cross Cimeto × UmRaby5 with value of 21.33%. Positive heterosis for 1,000-grain weight was found in the 20 crosses. Highly significant results indicated by 13 crosses ranging from 2.740 g in the cross UmRaby5 × Kokerete71 to 17.233 g in the cross Cimeto × UmRaby5, while two crosses showed non-significant positive heterosis. For grain yield/plant all crosses showed significant increase with highest value 19.256 in cross Crezo × Cimeto and followed by cross Cimeto × UmRaby5 (17.580) while all other crosses showed positive significant effect and ranged from 4.660 to 15.475.
From the previous information, it was concluded that crosses Crezo  Cimeto, Crezo  UmRaby5, Cimeto  UmRaby5, Crezo  LD357E and LD357E × Kokerete71 had significant desirable heterosis over mid parent for all studied traits. We found that the two crosses Crezo × Cimeto and Cimeto × UmRaby5 had aremarkab significant positive heterosis with high value of heterosis for all studied traits specially grain yield/plant. When the crosses had significantly desirable deterosis (positive or negative) over mid parents which revealed the predominance of non additive gene action controlling these traits while the crosses not appeared significantly heterosis, this indicate the additive gene action controlling these traits. These finding are in accordance with Ansari [29] and the theory, which have been to explain the mechanism of heterosis. The present results are in agreement with the findings of researcher like Kundan [30], Khattab [31] and Akbar [32].

Conclusions
The data indicated that all the traits show significant genotypic differences.
Genetic Analysis shows that all traits studied are controlled by dominance type of gene action. Presence of dominance gene action in traits like days to 50% flowering, plant height, flag leaf area, No. of spikes/plant, No. of grains/spike, 1,000-grain weight and grain yield/plant suggested improvement by hybridization.