جستجوی مقالات مرتبط با کلیدواژه "تلاقی دی آلل" در نشریات گروه "زراعت"

Maize (Zea mays L.) is considered as one of the most important cereals in the field of world production. Water stress due to water shortages and its various forms is one of the main and most common limiting factors of crop yield, especially in arid and semi-arid regions of the world. Therefore, in corn, identification, selection and use of tolerant cultivars against drought stress in order to prevent the reduction of crop yield is considered as one of the most important and essential issues in breeding programs. Breeding of high-yield and good quality cultivars is one of the main goals of the breeding program which requires comprehensive information about the genetic structure of the parents, as well as their general and specific combining ability, the level of heterosis, genes action, and their interaction with each other and the environment. Therefore, the present study was conducted to evaluate the gene effects, heritability and the control of yield and its components in drought stress conditions compared to normal conditions in corn. In order to select suitable breeding methods and take an effective step in the production of high yielding maize cultivars.

In order to estimate the gene action and heritability of important agronomic traits, five S7 maize lines in a 5×5 half-diallel cross with F1 hybrids derived from them in a randomized complete block design with two replications in two normal conditions (irrigation intervals of 5 days) and drought stress (8 days irrigation) were cultivated at the Research Farm of Graduate University of Advanced Technology, Kerman, Iran in 2017. Number of ear, grain number per row, grain row number, grain number per ear, ear length, 100-grain weight and grain yield per plant were evaluated in two conditions. The data were analyzed by analysis of variance and regarding the significance of the variance of treatments, the analysis was performed using Griffing's second method. In order to carry out the diallel analyzes by Griffing's second method in two normal and drought stress conditions and combined analysis of variance was used SAS command.

Combined analysis of variance showed that there was a significant difference between genotypes, environment and genotype×environment interaction for all studied traits, indicating the genetic differences between lines and corn hybrids. The results of combined variance analysis showed a significant interaction effects between general and specific combining ability with the environment, which indicates the different of inheritance of traits in each environment. The results of diallel analysis by second Griffing method under normal conditions indicated that the grain number per row, grain row number, grain number per ear and ear length more controlled by non-additive effects of genes, while these traits more controlled by additive effects of genes under water scarcity conditions.

The results of this study showed that although genes with both additive and non-additive effects played a role in controlling the traits, the contribution of each of these effects was different in controlling each of the traits. Also, the control of these traits was different in both normal and drought stress conditions, and the genes controlling these traits differed from environment to environment. The KSC704-S7-7 line showed positive and significant general combining ability for grain yield and most related traits in both conditions which can be used in breeding programs to improve grain yield and increase it. In addition, the P2×P4 cross under water scarcity conditions and the P1×P3 cross under normal conditions, which showed positive and significant specific combining ability for grain yield and most related traits, are introduced as the best hybrids for improvement and increase of maize grain yield for water scarcity and normal conditions, respectively.

Introduction Maize (Zea mays L.) is considered as one of the most important cereals in the field of world production. Water stress due to water shortages and its various forms is one of the main and most common limiting factors of crop yield, especially in arid and semi-arid regions of the world. Therefore, in corn, identification, selection and use of tolerant cultivars against drought stress in order to prevent the reduction of crop yield is considered as one of the most important and essential issues in breeding programs. In order to design and implement an effective and useful program, knowledge of the genetic control of the studied traits is essential the impact of environmental factors and the interaction between genetic and environmental factors. Among different methods of genetic analysis of quantitative traits, diallel analysis using Hayman method as an appropriate and efficient method for estimating the genetic structure of the populations in the relatively short time was considered by plant breeders. Therefore, the present study was conducted to evaluate the gene effects, heritability and the control of yield and its components in drought stress conditions compared to normal conditions in corn. In order to select suitable breeding methods and take an effective step in the production of high yielding maize cultivars. Materials and methods In order to estimate the gene action and heritability of important agronomic traits, five S7 maize lines in a 5×5 half-diallel cross with F1 hybrids derived from them in a randomized complete block design with two replications in two normal conditions (irrigation intervals of 5 days) and drought stress (10 days irrigation) were cultivated at the Research Farm of Graduate University of Advanced Technology, Kerman, Iran in 2017. Number of ear, grain number per row, grain row number, grain number per ear, ear length, 100-grain weight and grain yield per plant were evaluated in two conditions. The graphical analysis was carried out using the Hayman method and genetic parameters including additive variance (D), non-additive variance (H1 and H2) and covariance of additive with dominance effects (F) were also estimated by Hayman's proposed regression method. In order to carry out the diallel analyzes by Hayman method in two normal and drought stress conditions and combined analysis of variance was used SAS command. Results and discussion Combined analysis of variance showed that there was a significant difference between genotypes, environment and genotype×environment interaction for all studied traits, indicating the genetic differences between lines and corn hybrids. The simple effect of a for all traits, except for the number of ear and its interaction with the environment, was significant for all traits except number of ear, grain number per row and grain yield per plant which showed that additive effects play a role in controlling these traits and showed a different behavior in the two environments. The simple component b, which includes non-additive effects, was significant for all traits, and its interaction with the environment was also significant for all traits. The significance of the interaction between a and b effects with the environment indicates the difference in the type of additive and non-additive genes in both normal and drought stress conditions. Generally, the gene type for controlling traits and their gene action, potential of dominance and recessive genes in parents, and additive and dominance effects were different for most studied traits of this research in both normal and drought stress conditions. The graphical results of Hayman's analysis showed the role of over-dominance genes effects in controlling most traits in normal and drought stress conditions. Conclusions The results of this study showed that although genes with both additive and non-additive effects played a role in controlling the traits, the contribution of each of these effects was different in controlling each of the traits. Also, the control of these traits was different in both normal and drought stress conditions, and the genes controlling these traits differed from environment to environment. The results of narrow sense heritability and Hayman graphic analysis of traits showed that these traits were controlled by the non-additive gene effects. Therefore, it can be said that in order to breed and improve the genetic value of the population for these traits (yield and its components), the selection method will not be very successful, but it should use the phenomenon of heterosis and crossed the parents to produce hybrids.

Wheat yellow rust caused Puccinia striiformis Westend f. sp. tritici is one of the most economically important diseases of wheat in Iran and wordwide. In order to determine the heritability، gene action and estimate of genetics parameters for yellow rust resistance components، six bread wheat cultivars and advance lines including Pishtaz، MV17، Moghan 3، SERI/KAUZ، KAUZ//KAUZ/PVZ as well as a susceptible cv. Bolani were crossed using half diallel 7  7 design. Evaluation of F1s and parents were carried out using a randomized complete blocks design with three replications. Plants were inoculated with 134E134A+ race using talk powder. Four resistance components latent period، infection type، pustule density and size were measured. Analysis of variance for combining ability using Griffing method showed that general combining ability (GCA) and specific combining ability (SCA) for four were significant which implies the additive and non-additive effects in genetic control of these components. Among parents cv. MV17 with high GCA for all four traits was identified as suitable parent to be used in breeding programs for enhancement of resistance to yellow rust. Bolani had the highest GCA next to MV17 but for susceptibility. Crosses of MV17 with Bolani، Pishtaz، Kauz//Kauz/PVZ had higher SCA (-) for infection type، number of pustules and pustule size، and the highest SCA (+) for latent period in enhancement of resistance which implies non-additive (dominance and epitasis) gene effects in these crosses. Graphic analysis of Vr and Wr indicated that latent period، infection type، pustule size، and number of pustules were recessive in some genotypes but dominant in some others. Broad and narrow sense heritabilities for all four traits were relatively high، therefore، selection based on these traits for enhancement of resistance to this race is useful.

For estimation and graphical analysis of genetic parameters related to plant height، yield and yield components in lentil، six parental genotypes along with 30 F2 generations derived from compete diallel crosses between them (totally 36 genotypes) were grown in a randomized complete block design with three replications at research farm of Shahre Kord University in 2012. From each experimental plot، fourty F2 and ten parental plants were randomly selected and desired characteristics were measured. Estimation of average degree of dominance and results of graphical analysis showed that gene action was of complete dominance type for plant height. However، incomplete dominance type of gene action was observed for number of pods per plant، number of seeds per plant، 100 seed weight، seed yield and number of seeds per pod. The highest amount of narrow-sense heritability (77%) was observed for 100 seed weight and number of seeds per plant and the lowest (32%) for plant height. Proportion of genes with positive and negative effects (H2/4H1) differed from 0. 25 in all traits which indicated that the frequency of positive and negative genes is not equal in the parents.

Gene action and heritability of bread making quality characteristics for six bread wheat cultivars (Arvand، Atrak، Zarrin، Karaj-3، MV-17 and Navid) were studied in a 6×6 full-diallel cross. All crosses among the parents were made in 2009-2010 cropping season. Parents and their hybrids were grown in a randomized complete block design with three replications in research field of Mahidasht station، Kermanshah، Iran، in 2010-2011 cropping season. The bread making quality attributes were recorded and analyzed by Jinks and Hayman’s method. Analysis of variance of data showed significant differences (P<0. 01) among the genotypes for all studied traits. Results of graphical analysis based on Hayman’s method showed the prevalence of additive effect over the non-additive effect for all traits. The highest and lowest heritability of traits belonged to kernel hardness index and falling number which was 79% and 31% respectively. Embryo and endosperm additive variances for grain protein content، kernel hardness، water absorption، wet gluten and gluten index were similar to Hyman’s method. Mother’s effects in triploid’s method and Hyman’s method for baking quality traits were similar and significant. The additive and non additive gene actions were also observed. Considering the significant role of additive effects on control of 1000 grain weight، seed protein content، moisture content of grain، grain hardness and bread volume، therefore they can be improved in breeding programs via selection procedures.

In order to estimate the gene action and heritability of 8 important agronomic traits, 6 genotypes of rice were studied in a 6×6 half-diallel cross. Parents and their progenies were grown in a randomized complete block design with three replications in Field Research Station of the University of Guilan, Rasht, Iran, in 2006 cropping season. Eight traits including pre-anthesis phase, post anthesis phase, flag leaf area, panicle length, number of grain per panicle, 1000 grain weight and grain yield were evaluated. Analysis of variance of data showed significant differences (p<0.01) between genotypes for all studied traits. Results from graphical analysis based on Hayman method showed that non-additive effect for all traits, except pre-anthesis phase and panicle length, were important than the additive effect. Pre-anthesis phase and panicle length were controlled by partial dominance effect (with higher additive effect) and the other traits were controlled by over-dominance gene effect in selected genotypes. For panicle length, the parents had more recessive allele frequencies, while for other traits the frequencies of dominant alleles were greater in parents. Narrow-sense heritability varied from 0.165 to 0.794 for duration of post-anthesis phase and panicle length, respectively. It can be concluded that both hybridization and selection approaches can be used to improve panicle length and duration of pre-anthesis phase, however, for the other traits including grain yield heterosis and hybrid development are recommended.

In order to study genetic of quantitative traits in wheat under normal and moisture stress conditions, several genetic parameters such as average degree of dominance, proportion and distribution of dominant and recessive alleles in all parents and dominance direction were evaluated in ten cultivars of bread wheat, using a half diallel. Parents and their hybrids were separately planted in a randomized complete block design under normal and moisture stress conditions in the second year. Results of analysis of variance in normal moisture condition showed genetic variation among genotypes for most of the traits except for tiller and fertile tiller number, awn length and 50% heading date, whereas in stress condition results of analysis of variance were not significant for awn length, 50% heading date, dry weight of root and flag leaf area. There were over dominance effect for number of spikelet per spike, number of kernel per spike, 1000- kernel weight, biomass, weight grain yield and harvest index, complete dominance for stomata number per unit of leaf area, and partial dominance for peduncle length, spike length and dry weight of root in normal moisture condition. The results in normal moisture condition also showed that all traits were controlled by dominant alleles, except number of stomata per unit of leaf area that was controlled by recessive alleles. In stress conditions there were over dominance effect for number of spikelet per spike, spike length and number of kernel per spike, complete dominance for number of stomata per unit of leaf area, and partial dominance for peduncle length, 1000- kernel weight, biomass, weight, grain yield and harvest index. In stress condition, all traits were controlled by dominant alleles except 1000-kernel weight that was controlled by recessive alleles.

In order to determining and identification of the nature of gene action in inheritance of different traits, 56 genotypes (crosses and reciprocals) developed from diallel crosses of eight maize inbred lines along with parents were evaluated for important quantitative traits using randomized compelet block design with three replications in the Experimental Field Station of Seed and Plant Improvement Institute, in 2005 cropping season. Diallel analysis revealed the presence of over-dominance gene action in controlling grain yield, kernel number per ear row, kernel depth, ear length, plant height. Genes with partial dominance action were revealed in controlling number of rows per ear, numer of leaves and days to tasseling, while genes controlling 300 kernel weight and ear diameter showed dominant effects. Graphic analysis showed that for early reproduction stage, and increasing the grain yield, member of rows per ear and kernel number per row, length and diameter of ear, leaf number, plant height, dominant genes ware involved, while, for 300 kernels weight, recessive genes were effective.