جستجوی مقالات مرتبط با کلیدواژه « diallel cross » در نشریات گروه « زراعت »

Wheat performance is always affected by climate change and environmental stresses such as drought stress. Development of high-yielding cultivars requires genetic diversity. Awareness about heritability of traits can be helpful in determining the appropriate breeding strategy for any environmental conditions. By progeny trial after a diallel crossing, the function of genes and inheritance of quantitative traits can be estimated. This increases the ability to select parental lines, to participate in crosses, and determines the management of generations in the segregating populations.

In order to understand the genetic structure of grain yield and some morphological traits of bread wheat under normal and drought stress conditions, eight bread wheat cultivars including Star; Tirgan; Ehsan; Shirodi; Bam; Tajan, Yang and Akbari were planted in the crossing block and direct crosses were performed among the eight cultivars to produce F1 generation. This research carries out in Gorgan agricultural research station in 2020-2021 cropping season, under normal and drought stress conditions. The progenies of the crosses with their parents were evaluated based on a randomized complete block design (RCBD) with three replications. Imposing stress by terminating irrigation was initiated at the Zadoks 60 (full heading emergence) stage.

Combined analysis of variance under normal and drought stress conditions showed that the simple effects of genotype and environment were statistically significant in all traits. Also, the interaction effects of genotype×environment was statistically significant for grain yield, biological yield and 100-kernel weight. In fact, for these traits the response of genotypes was different under normal and stress conditions. Analysis of variance of Griffing's diallel method showed a statistically significant difference between genotypes in all studied traits. Therefore, among the progenies of the crosses it is possible to select superior genotypes. In biological yield and grain yield under both normal and drought stress conditions, Tirgan cultivar had the highest general combining ability, while Star cultivar showed the lowest general combining ability. Tirgan cultivar can be used to increase grain yield and biological yield under both conditions. In plant height, peduncle length and harvest index, Tajan×Yang, Ehsan×Shirodi and Bam×Yang crosses had the maximum specific combining ability, respectively. In other traits, in each condition, an individual cross had the highest specific combining ability. Under normal conditions, Tajan×Akbari cross had the highest specific combining ability in grain yield. Under drought stress conditions, Bam×Akbari cross had the highest specific combining ability in biological yield and grain yield, it simultaneously had a high specific combinability in 100-grain weight, harvest index and number of grains per spike. Therefore, Bam×Akbari cross was determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under drought stress conditions. The ratio of additive variance from genetic variance for plant height and peduncle length was greater than dominance variance. Subsequently, the highest narrow-sense heritability in both normal and drought stress conditions was related to plant height and peduncle length. In both normal and drought stress conditions, the highest degree of dominance was related to harvest index traits and number of grains per spike, respectively. Therefore, in these traits the lowest narrow-sense heritability, the lowest Baker's genetic ratio and the highest ratio of dominance variance from genetic variance were observed in both normal and drought stress conditions. In grain yield, a high ratio of dominance variance from genetic variance was assigned under normal (84%) and drought stress (88%) conditions, hence low narrow-sense heritability was observed under normal (8%) and drought stress (5%) conditions. In general, in grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions, which indicates a greater ratio of non-additive effects under drought stress conditions.

The results of this study showed that under both conditions, Tirgan cultivar had the highest general combining ability in grain yield and biological yield. Tajan×Akbari and Bam×Akbari crosses were determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under normal and drought stress conditions, respectively. In grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions. Based our results under both conditions in the progenies of the crosses, genetic improvement can be done in plant height and peduncle length in the initial generations, but for other traits including grain yield and its components, selection should be postponed to more advanced generations.

To estimate genetic parameters of yield and yield component of chickpea, six chickpea genotypes were crossed in complete diallel crossing scheme in glass houses of Seed and Plant Improvement Institute in 2007. Parents, direct and reciprocal crosses (36 entries) were evaluated using randomized complete block design with four replications at Grizeh station, Sanandaj, Iran in spring of 2017 growing season. Plant traits including day to flowering, day to maturity, plant height, seed no.pod-1, pod no.plant-1, drought tolerance score, 100 seed weight and seed yield were measured and recorded during the growing season. Statistical analysis for F1 hybrids and parents as well as diallel analysis were performed using Griffingchr('39')s model 2 of method 1. The results showed that there were significant differences between parents and F1 hybrids, which indicated a wide genetic variability for traits of interest. It was revealed that it would be possible to improve the agronomic traits of chickpea using this genetic resources. Specific combining ability (SCA) was significant for plant height, 100 seed weight and seed yield and the important role of non-additive component in inheritance of these traits was identified. Maternal inheritance had important role in heritability of seed no.pod-1, pod no.plant-1, drought tolerance score and seed yield. Samin" and FLIP 96-154C parents had the highest general combining ability for seed yield, respectively. The effects of specific combining ability revealed that, under conditions similar of this study, Azad × FLIP 96-154C cross was the best specific combiner for seed yield and seed no.pod-1. Considering the results of this study, there was considerable variation in cytoplasmic genes carried by these chickpea genotypes that can be used in breeding for dvelopment of high yielding, with yield stability and early maturity, chickpea cultivars.

Wheat is attacked by many pathogens during the growing season, including rust. The causative agent of fungal wheat brown rust called Puccinia recondita f. sp. is also known as leaf rust. The most important way to control brown rust disease is to use resistant cultivars that effectively control and reduce its damage. The most important way to control brown rust disease is to use resistant cultivars that effectively control and reduce its damage. The aim of this study was to investigate the inheritance of brown rust resistance in different wheat cultivars and estimation of genetic parameters using diallel crossing.

Six bread wheat cultivars including Gonbad, Shiroudi, Darya, Atrak and Moghan 3 genotypes with susceptible Bolani cultivar and 15 F1 progenies from one-way diallel crosses were studied. his study was conducted as a randomized complete block design with three replications in field and greenhouse conditions. Traits included infection type, severity of infection, area under disease progression curve and incubation period. Data analysis was performed using SAS ver 9.1 and Excel software and estimation of genetic parameters and heritability of traits were studied by diallel analysis using Griffing's second method with fixed model and Jinks and Hayman method.

Analysis of variance showed that there was a significant difference among genotypes for all traits, indicating genetic variation for these traits and thus genetic analysis could be performed. The mean squares of general and private combining ability were significant for all traits, indicating the importance of both enhancing effects and dominance of genes in inheriting these traits. The Baker ratio indicated the same importance of additive effects and dominance for the incubation period and for the other traits indicated greater importance of additive effects. Estimation of genetic parameters by Jinks and Hayman method showed that for all four traits, the amount of D component was lower than the dominance components (H1 and H2), indicating that the dominance component was more important than the additive component in controlling these traits. The sign of F was positive for all traits, so the frequency of dominant alleles was higher than that of recessive alleles. Wr-vr statistic was significant for all studied traits, indicating the presence of inorganic effects (epistasis). In other words, the significance of this statistic indicates the inaccuracy of the additive-dominance model for traits.

Based on the traits evaluated in field, Atrak cultivar and in greenhouse, Gonbad cultivar had good resistance to brown rust. Narrow-sense heritability of traits was estimated to be between 51 and 86%. Estimation of genetic parameters showed that additive-dominance model was not sufficient. In other words, at least resistance is predictable in resistant cultivars.

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.

To evaluate the general and specific combining ability of maize lines, five S7 maize lines and their offsprings were evaluated in randomized complete block design with two replications under normal and water deficit conditions at the research field of Graduate University of Advanced Technology, Kerman, Iran, in 2017 and grain yield and its components were measured. The results of analysis of variance indicated that there was a significant difference between lines as well as general and specific combining ability of parents and hybrids. Based on the results of the diallel analysis by second Griffing’s method, number of grain per row, number of grain rows, number of grain per ear, ear length and 100 grain weight were more influenced by the additive effects than the non-additive gene effects, while the number of ear was more controlled by the non-additive gene effects and grain yield per plant was approximately controlled by equal portion of the additive and non-additive gene effects. The line KSC704-S7-1 showed significant and positive general combining ability for grain yield and more related traits under both water deficit stress and non-stress conditions, so this line can be used to improve grain yield in breeding programs. In addition, P1×P3 and P2×P5 hybrids showed significant and positive specific combining ability for grain yield and most related traits under water deficit stress and normal conditions, respectively, which are introduced as the best hybrids for improving maize grain yield under water deficit stress and normal conditions, respectively.

Barleys one of the important four major crops in the world after wheat, corn and rice. About 2.16 million hectare of arable land was cultivated by barely in 2011-2012. In order to investigate heritability and gene action was used barely half-diallel of 7 × 7 in some barley-related yield traits. For this purpose were used in 6 barley genotypes with Sahra variety (the native desert). Tests carried out in a randomized complete block design with three replications at the Agricultural Research Station of gorgan (Iraqi Research Station neighborhood) 2011-2012 and 2012-2013 years. The traits were of grains per spike, grain weight per spike, spike weight, grain weight, 1000 grain weight, spikelet number, plant height, spike length, peduncle length and days to maturity. The results showed significant mean square of parents and crosses for all traits. Therefore, performed genetic analysis for traits In most of the traits was estimated to be non-additive variance greater than additive, also, calculation of average degree of dominance indicated for all traits except spike lengthover dominance genes effect, graphical analysis that confirmed it. Broad sense heritability not so high for traits, So phenotypic selection is not an appropriate method and the results will not be consolidated in next generations. So, hybridization will be more effective method of selection for traits in order to achieve the objectives of the reform. 166/352 genotypes for temperate regions has the highest average seed number and weight of grains per spike and the highest average seed number and weight of grains per spike and 166/352×283/352 crosses have become the highest average grain yield related traits.

In this study, half diallel cross method with Grifing method II and model mixed B was used to evaluate genetic parameters for physiological and morphological traits in seven lines of sesame and their 21 F2 populations under normal irrigation and water limited (water withholding before flowering) conditions. Mean of evaluated GCA/SCA under normal irrigation indicated that days to flowering, days to end of flowering, flowering duration, days to maturity, number of capsule per main stem, 1000-seed weight, main stem yield, capsule length, internode lengh, number of infertile nodes, number of capsule bearing nodes, and total number of nodes were mostly controlled by additive gene effects, some by non-additive gene effects and in some cases by a balance between the two genes mode of actions. Heritability in the broad sence varied from 58.4% for internode length to 97.7% for number of capsule per plant. Narrow sense heritability was high for number of capsule per plant (82.5%) and days to maturity (80.5%), indicated high selection efficiency for these traits under water limited condition. All the evaluated traits were governed by additive effects which indicated a shift in genetic control of the traits compared to normal irrigated condition. Broad sense heritability appeared to be unchanged but evaluation of narrow sense heritability was lower in water limited condition compared to normal irrigated, which may indicate reduction in breeding progress rate.

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.

To study general and specific combining ability of some rice varieties for grain physical properties and milling quality، a diallel design with five parents (Hashemi، Vandana، Kadous، Shahpasand and IR36) was used. Parents and their F1 progenies (25 genotypes) were grown in a randomized complete blocks design with three replications in the Research Field of Rice Research Institute of Iran (RRII)، Rasht، Iran، during 2012، and nine different characteristics were recorded. Analysis of variance showed that there were significant differences among genotypes and also general and specific combining ability for all of studied traits، showing the role of additive and non-additive gene effects. Furthermore، the effects of reverse crosses for all studied traits except، degree of grains whiteness، were significant which indicated the role of maternal effects. The significance of MSGCA/MSSCA ratio، Baker ratio (genetic ratio) near to one and high narrow-sense heritability for physical characteristics showed that the additive gene effects controlling these traits were important than the non-additive gene effects، while non-significance of MSGCA/MSSCA ratio، Baker ratio (genetic ratio) less than one and low heritability for milling characteristics showed the role of non-additive gene effects. Results from graphical analysis based on Hayman method showed that all physical characteristics related to grain quality were controlled by partial dominance effect، while all milling properties were controlled by complete dominance to over dominance gene effect. The results of this research showed that the selection of elite progenies is suitable method to improve the physical characteristics in studied population، while hybrid production method will be suitable to improve milling quality in this population.

In order to evaluate the heterosis and combining ability of petunia inbred lines for ornamental traits, 12 hybrids were derived from direct and reciprocal crosses of 4 petunia inbred lines viz. L5 (P1), L8 (P2), L11 (P3), and L17 (P4). In the second year, the derived hybrids and their parents were planted in a randomized complete block design with three replications. The measured traits in F1 generation were, plant height at first flower, number of flower per plant, days to flowering, flower diameter, flower tube diameter, flower tube length, flower length, flower longevity and flower fragrance. The significance of specific combining ability (SCA) and general combining ability (GCA) for the most studied traits revealed that both additive and non-additive gene effects contributed to the inheritance of the traits. Not statistically significant of GCA/SCA ratio and the degree of dominance more than one showed that the contribution of non-additive gene actions was relatively higher than that of additive for all studied traits. For flower diameter, parent P2 and hybrid P1 × P2 had the highest GCA and SCA effects, respectively. Reciprocal effects were significant in all measured traits except for flower longevity and flower length. Estimation of heterosis showed that combinations P1 × P3 and P2 × P3 had the highest heterosis relative to mid and high parents for flower number and diameter among all hybrid combinations, respectively.

The study was conducted to estimate of heterosis، combining ability، heritability، maternal effects and gene effects of grain yield and yield components in durum wheat in field condition. A complete diallel cross of seven durum wheat genotypes were evaluated in a randomized complete block design with two replications. The experiment performed at normal condition for wheat. Distance between rows and plants in each row were 25 and 4 cm and length of row was 2 meter. The analysis of variance revealed significant differences among genotypes for all traits and significant heterosis was observed for all traits except spike length and grain yield per plant. General combining ability variance was highly significant for all the characters and specific combining ability variance was highly significant for all the characters except spike length. The mean square ratio of GCA to SCA implied the importance of additive genes effects in expression of grain weight per spike and spike length. Reciprocal mean squares were significant for all traits except spike length. Dipper-6 showed the highest GCA for important traits such as grain yield per plant، grain weight per spike، flag leaf area and grain number per spike. Broad-sense heritability estimates ranged from 0. 93 (for grain number per spike and grain weight per spike) to 0. 29 (for flag leaf area). Narrow-sense heritability estimates ranged from 0. 53 (for grain number per spike) to 0. 10 (for flag leaf area).

To determine the inheritance of germination related traits in bread wheat, a 8×8 diallel cross design was carried out in 2007 at the Ardebil Branch, Islamic Azad University, Iran. The F1 and F2 seeds were germinated under osmotic stress and also subjected to atmospheric drought stress. Different germination rate indices, seedling characteristics and germination recovery after desiccation were measured and recorded. For evaluating the relationship between germination characteristics and drought tolerance, 18 wheat varieties including the parents of diallel cross were grown under irrigated and rainfed conditions in the field. Results of these experiments indicated that germination rate indices had high narrow sense heritability and close relationship with drought tolerance. Among seedling characteristics, coleoptile length under normal condition showed high narrow sense heritability and a close relationship with drought tolerance. Root number under stress conditions was considered as a moderately heritable character with significant relationship with drought tolerance indices. Despite of the close relationship of root: shoot length ratio with drought tolerance, it had low narrow sense heritability. Germination recovery showed negative relationship with drought tolerance and had low narrow sense heritability.

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.

To study inheritance of morphological traits associated with earliness and their relationship with yield, six genotypes of cotton were studied in a half diallel cross in 2003 in Darab. Fifteen F1 and six parents were evaluated in a complete block design with three replications. The results showed that differences among treatments were significant for seed cotton yield, earliness, plant height, date of first squire and mean maturity data. General and specific combining ability (GCA and SCA) effects were estimated by the method 2 of the Griffing’s model I. Mean square of general combining ability (GCA) was significant for all studied traits. Specific combining ability (SCA) was significant only for yield. GCA/SCA ratio was significant for all studied traits except for yield. Determination of genetic parameters, statistical indices and graphical analysis by Jinks–Hayman method showed that gene actions for yield and earliness were over-dominance, while plant height, days to first squire and mean maturity data showed partial dominance. All of the traits had high board sense heritability. Narrow sense heritability was also high for all traits except yield.

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.