جستجوی مقالات مرتبط با کلیدواژه « Dominance » در نشریات گروه « زراعت »

In Iran, as in most poor and developing countries, wheat is the most important food in the diet of the people. Therefore, the field of study and research on various aspects of this important and strategic crop is still open to relevant researchers and experts. Given that the achievement of yield potential in crops, including wheat, is influenced by genetics, environmental conditions, their interaction and the application of proper management in the optimal use of available resources, so the genetic capacity of the existing germplasm should be used to produce suitable breeding lines in order to make the most of natural and climatic resources. Therefore, screening genotypes, selecting the proper parents, and modifying them through conventional and new methods can still be helpful. Estimating genetic effects and studying the inheritance pattern of important agronomic traits and in general knowledge of germplasm genetic information and knowledge of the genetic system of the studied trait is one of the most useful tools in designing breeding methods to improve target traits. This study aimed to estimate the genetic model controlling important agronomic traits and also to estimate heterosis and heritability in two bread wheat cross under normal and terminal drought stress conditions using generation mean analysis method and multivariate regression analysis.

A field investigation materials consisted of basic generations obtained from the crosses of a local cultivar “Marvdasht” (female parent) with two cultivars “Sistan” and “Norstar” (male parents). Both the crosses and resultant progenies were performed and developed under field conditions. All the six generations derived from the above two crosses were sown under two distinct conditions, normal (non-stress) and terminal drought stress in a randomized complete blocks design with three replicates at the Research Farm of Razi University, Kermanshah, Iran during the next cropping season (2015-2016). Terminal drought stress was imposed in Mid-May; while non-stress plots were irrigated whenever required. Weeds were controlled manually when necessary. The rainfall in 2015-2016 was 653 mm. Data from 10 plants in each of P1, P2 and F1 generations, 30 plants in F2 and 15 plants in each of BC1 and BC2 were randomly recorded per replication. Statistical analyses were done using different methods and software.

Significant differences between the generations were found for most of the traits which indicated the presence of genetic variation in the plant populations and scope of improvement through breeding methods such as selection and expression of heterosis. The scaling and joint scaling tests revealed that the simple additive-dominance model was not sufficient to explain the genetic variation in the crosses for all the studied traits apart from the number of spike per plant, main stem diameter and number of spikelet per spike at Marvdasht × Sistan, and hundred kernel weight and peduncle length at Marvdasht × Norstar. It could be concluded that the inheritance of these traits is governed by epistasis gene action. The results of analysis of variance obtained by regression method showed that fixable genetic effects had the highest relative contribution of the generation sum of squares for most of the traits in both crosses and under both normal and drought stress conditions. High estimates of broad-sense heritability for hundred kernel weight (0.67) in normal conditions at Marvdasht × Sistan cross and plant height (normal: 0.76 and stress: 0.67) and peduncle length (normal: 0.72 and stress: 0.67) at the Marvdasht × Norstar cross shows that the effects of dominance have a greater role in the inheritance pattern of these traits and therefore it is possible to produce hybrid varieties to improve these traits.

The results of generation mean analysis showed that the type and action of genetic effects were variable in both crosses and for different traits and indicate the need to adopt a special breeding method to improve them. The presence of duplicate mode of gene interactions signified the involvement of epistatic effects for most of the traits. Based on the present investigation, it could be inferred that the genetic control model was somewhat similar for most of the traits under both conditions at both crosses, and it has not been largely affected by drought stress.

In order to investigate the role of inter-species interference and competitive outcome of barnyard grass (Echinochloa crus-galli) and bulrush (Bolboschoenus planiculmis) weeds with Guilaneh cultivar of rice, a factorial experiment with two factors including weed species (barnyard grass and bulrush) and rice: weed ratios in each pot (0: 4, 1: 3, 2: 2, 3: 1, and 4: 0) was conducted as a randomized complete-block design with three replications. The results showed that, except for height, all other traits of rice decreased more in competition with barnyard grass than competition with bulrush. The percentage of more reductions of traits in rice-barnyard grass competition than rice- bulrush competition, averaged over planting ratios, were 10 and 21% for biological yield, 12 and 23% for seed yield, 10 and 21% for number of panicle, 13 and 25% for number of filled seeds, 7 and 16 for total number of seeds, and 10 and 17% for number of tillers on pot and single plant levels, respectively. These results, along with the replacement series diagrams studies have indicated the severe competition of barnyard grass with rice plants. However, no significant difference in the competitive effect of the two weed species, as well as the insignificant dominance index and the ratio of barnyard grass and bulrush competition, indicates the importance of bulrush as a new weed in rice fields. Therefore, effective management of bulrush in addition to barnyard grass should be taken into consideration in the development of the weed management programs in paddy rice fields.

In order to investigate the effect of different sources of nitrogen fertilizer on the relative frequency, density and biomass of safflower, a factorial experiment was conducted in a randomized complete block design with three replications located in the research farm of faculty of agriculture university of Jiroft in 2018-2019 year. The first factor at two levels included the use of manure and non-use of manure, the second factor included different nitrogen fertilizer sources at five levels of control, urea fertilizer, urea fertilizer with sulfur coating, ammonium nitrate, nitroxin and nano nitrogen. The results showed that in all three stages of sampling weeds, Clover (Trifolium repens L.) and Umbrella sedge (Cyperus rotundus L.) weeds had the highest and Bermudagrass (Cynodon dactylon) and Sorrel (Rumex crispus L.) had the lowest relative abundance. Different sources of fertilizer had a significant effect on biomass weeds of clover, umbrella sedge, common mallow and other weeds during three sampling stages. Based on the results of mean comparison, the highest biomass was obtained of clover weed in the first stage in the treatment of manure with chemical fertilizers urea (17.04 g). The lowest biomass was obtained in no manure in control (6.47 g) and nano nitrogen fertilizer (4.63 g). Shannon and Margalef indices in the first stage of sampling 0.96 and 0.94, the second stage of sampling 0.79 and 1.06 and the third stage of sampling 0.63 and 1.11 respectively in the treatment of manure was more than to non-use manure. Sources of urea and urea fertilizers with sulfur coating had higher weed diversity index than other treatments. According to the results of this study, it is suggested to use biological sources of nitrogen in order to prevent weed infestation and competition with the target plant.

Bilateral diallel crosses of eight rapeseed genotypes were used to graphically analyze and estimate of genetic parameters for agronomic and physiological characteristics. F1 along with their parents (64 genetypes) were planted in a randomized complete block design with three replications at Gorgan Agriculture Research Station, in 2019-2020. The results of analysis of variance showed that a and b components were significant for all traits. The results of the Jinks-Hayman test indicated that hypothesis of the genetic analysis were satisfied for pod length, number of pod per lateral branches, number of pods per plant and 1000-grain weight traits. Analysis revealed significant values for D and H1 estimation for all traits, which indicated the existence of both additive and non-additive effects on genetic control of these traits. While the proportion of non-additive variance was higher than the additive effects for all traits, which was in agreement with high mean levels of the degree of dominance. The positive and significant sign of F confirmed that there are much more dominant alleles than recessive alleles in parents, regardless of whether they have a negative or positive effect. Based on Hayman graphical analysis, 1000-grain weight was influenced by the dominance of genes. Narrow-sense inheritance levels were low for all traits, which could indicate a greater impact of environmental and non-additive effects on their genetic control. The results showed that selection-based methods were not very effective in canola yield improving and production of hybrids and exploiting the effects of gene dominance is necessary.

The selection of suitable yielding maize cultivars to water deficit is one of the main objectives of the breeding programs. Therefore, selection of a suitable breeding method for better productivity from genetic potential of stress tolerance and understanding the type of controlling genes action and their inheritance is very important. In this regard, genetic analysis of some of the agronomic traits of the generations resulting from cross between corn inbred lines MO17 (Tolerant to stress) and B73(stress sensitive) including: F1,F2,F3,BC1 and BC2 along with parents in three irrigation conditions (normal, 50 and 75 millimeter evaporation from class A evaporation pan) was evaluated in 2017-2018. Experiment was conducted in each irrigation conditions in a randomized complete block design with 20 replications. The traits including grain yield per plant, biomass per plant, 1000 grain weight, ear diameter, ear weight and rows number were measured. Combined analysis revealed that there was a significant difference between the studied generations for maize agronomic traits. The results of the scaling test indicated the existence of epistatic effects for most traits such as grain yield per plant, biomass per plant and1000 grain weight under different irrigation conditions In most of the traits such as grain yield per plant, biomass per plant, row number per ear and 1000-grain weight, dominance effect was significant at 5% and 1% probability level. About rows number three-parameter model was the best fit model, in all three conditions. For most of studied traits, six parameters models were significant in different irrigation conditions, but was not significant for plant height under normal irrigation conditions and 75 mm evaporation due to maternal effects, gene association and multiple chi-square epistasis. Estimation of the dominance degree above 1 for grain yield and less than 1 for ear diameter in all three irrigation conditions  indicated that there was a phenomenon of over dominance and incomplete dominance in the control of them. High levels of genetic broad sence and narrow sence heritability suggested that genetic effects and additive effects have a greater role in the inheritance of 1000 grain weigth in all three irrigation conditions.

In order to study the type of action of genes and inheritance of traits in chickpea, the generation mean analysis was accomplished using the cross of six cultivars of chickpea called Pirouz, Bivanich, Flip51-87c, Iccv2, Kaka, and Azad. Parent seeds along with seeds of F1, F2, BC1, and BC2 were cultivated in a randomized complete block design with three replications, and eight traits including plant height, number of seeds per plant, number of pods per plant, number of hollow pods per plant, number of double-grain pods per plant, 100-seed weight, number of days to 50% flowering, and grain yield were evaluated. The variance analysis results indicated that the mean squares of generations were significant for all the traits, so the generation mean analysis for the studied traits was performed. Based on the results of generation mean analysis for all the studied traits besides the additive and dominant effects, epistatic effects were also fitted which indicates the complexity of the inheritance of these traits. The results also showed that the plant height was controlled by incremental and dominating effects. It was also determined that the dominant genetic effect has the most significant role in the inheritance of most of the studied traits.

Wheat is the oldest and most important cultivated crop in the world and has fundamental role in human food security. Drought is one of the most common environmental stresses that affect growth and development of plants. Most parts of Iran’s cultivation land are located in arid and semiarid regions and because of water deficiency, plant stress appear and wheat performance reduces severely in these regions. In such circumstances, the production of drought tolerant varieties has special importance. Understand the genetic basis of yield and yield related traits is necessary in breeding programs. One of the best approaches to determine genetic parameters is generation means analysis method, due to it allows breeders to predict epistasis. In order to estimate genetic parameters and evaluation of gene action controlling agronomic traits in bread wheat under moisture stress, F4 families derived from cross between Roushan and Kavir along with F2, F3 and parents, were evaluated under moisture stress.
Field experiment was carried out in research field of Shahid Bahonar University of Kerman, during growing season of year 2013-2014 using Augmented design with 5 known check cultivars (Roushan, Falat, Mahdavi, Karchia and Shahpasand). Stress treatment was cut off irrigation at heading stage. Grain yield and some agronomic traits were measured. Generation means analysis method was used to determine genetic parameters including additive effect (d), dominance effect (h), additive × additive [i], and dominance × dominance effect [l] were evaluated for different traits. Generation means analysis was carried out using equation 1.
Y= mα[d]β[h]α2[i]αβ[j]β2[l] (1)
Broad and narrow sense heritability of evaluated traits were estimated according to equation 2 and 3.
The study revealed a complex genetic control for studied traits. Genetic variation in F2, F3 and F4 was more than parents. Five-parameter model including m, [d], [h], [i] and [l] explained genetic variation for plant height, awn length, grain number per plant, 1000-grains weight, biology and grain yield. While, a four parameter model including m, [h], [i] and [l] were explained genetic diversity of grain filling period and a four-parameter model including m, [d], [h], and [l] was valid for explaining genetic variation of number of spike per plant and harvest index. A three parameter model including m, [d], [i] made the significant contributions to the inheritance of spike length. The additive genetic variance was detected as the most important genetic effect in controlling grain yield, biologic yield, harvest index, 1000-grian weight, awn length, spike length and grain filling period. Therefore, selection in early generations is effective for these traits. High narrow sense heritability of these traits proposes that the most part of genetic variance could be fixed in segregating generations. Broad and narrow sense heritability of studied traits in the present population were 0.46 to 0.96 and 0.16 to 0.93, respectively. 1000-grian weight, grain yield, biologic yield, grain filling period and harvest index had the highest narrow sense heritability, respectively. Therefore in the present population, selection based on these traits could result in good genetic gain. While, dominant effect was more important for plant height, number of spike per plant and grain number per plant. Significant differences between broad and narrow sense heritability of these traits has confirmed the fact that the dominance effect is very important. Therefore, selection should be made in later generations until desirable genes are fixed. Low narrow sense heritability was observed for number of spike per plant (0.16). Therefore, selection based on this trait can not have good genetic gain in present population. In this study, environmental variation was less than additive and dominance variance that show accuracy of the estimations and low impact of the environment on evaluated traits. Plant height, number of spike per plant and grain number per plant showed one degree greater than of dominance. These result showed over dominance of genes controlling mentioned traits.
Based on the results obtained in this experiment, it can be concluded that there is a considerable genetic diversity in the population F2, F3, F4 derived of Roushan and Kavir cross which can be used as a high potential population for genetic improvement of evaluated traits. The Results showed that additive variance was more important than dominance in genetic control of evaluated traits. So, selection during early generations is recommended in wheat breeding program of this population.

This study was conducted as intercropping of garlic and peas to assess the diversity, bio-mass, and population of weeds in two regions of Gonbad Kavoos and Sari during autumn 2013. The experiment was implemented in a randomized complete blocks design with three replications in both regions. Different combinations of intercropping were considered in nine levels of garlic and peas pure cultures, replacement intercropping of 75:25, 50:50, 25:75%, and additive intercropping of 100, 100, 100, 100흍 for garlic and peas. Results showed that the average biomass value of weeds in Sari (2080.5 gm-2) was greater than in Gonbad region. However, a higher weed density (44.88 m-2) was observed in Gonbad. The highest levels of biomass (3387.3 gm-2) and density (61.83 m-2) of weeds were measured for garlic pure culture in Sari and the intercropping replacement of 75% peas:25% garlic in Gonbad Kavoos. Mean value of Margalef species richness index, Menhinick index, and Shannon-Wiener diversity index were calculated as 1.33, 1.01, and 1.96 in Sari, respectively, which were higher than 0.86, 0.7, and 1.03 in Gonbad. By contrast, the Simpson's dominance index (0.63) for peas pure culture and Shannon-Wiener evenness index (0.89) to replacement intercropping of 75% peas: 25% garlic were greater in Gonbad Kavoos. Berger-Prager diversity index (0.77) for pure garlic culture, and both Shannon diversity (1.42) and Simpson's diversity (3.94) indices for replacement intercropping of 75% peas: 25% garlic were greater in Sari. There was a difference between the two regions in terms of climatic and edaphic characteristics which resulted differences in weed diversity indices, intercropping increased diversity while reducing dominance as compared to the monoculture cropping system in both regions.

A 5×5 half diallel cross set of chickpea (Arman، Hashem، ILC588، ICCV2 and ILC3979) was studied to estimate gene effects and genetic parameters of seven traits. According to diallel variance analysis، only additive genes effects were found significant for plant height، basal pod height and number of primary branches. In addition to the significant additive gene effects، dominant gene effects were significant for 100-seed weight، harvest index، seeds and seed yield per plant. The degree of dominance average (H1/D) 1/2 was lower than one for plant height، basal pod height and harvest index، indicating partial dominance but for 100-seed weight، seeds and seed yield per plant it was higher then one and for number of primary branches it was equal to one that indicating over dominance and complete dominance respectively. The narrow-sense heritability were high for harvest index (67%)، 100-seed weight (56%)، basal pod height (47%) and plant height (42%) indicating that great genetic gain could be achieved for these traits. Dominant direction was negative and high for all traits with exception of plant height and basal pod height; hence for these traits amplifier alleles were dominance.

In order to study the genetic control of common smut in maize, eight inbred lines (two resistant, K1264/1 and K47/2-2-1-21-2, two moderately-resistant K74/1 and K47/2-2-1-4-1, two susceptible K19/1 and K19, and two very susceptibles K3304/1-2 and K47/2-2-1-3-3-1-1, were crossed in diallel in 2005 and evaluated in 2006 under artificial inoculation. All diallel crosses and parents were inoculated with a suspension of 106 sporidia per ml, 7-10 days after silking using tip injection method. At physiological maturity, disease severity was evaluated in each ear. Diallel analysis revealed the role of genes with additive and non-additive effects in genetic control of resistance. Lines K1264/1 and K74/1 with the highest negative GCA, had the least disease severity, while, K3304/1-2 with the highest positive GCA, had the highest infection .Cytoplasmic effect was also revealed for heritance of resistance to common smut. Ressesive alleles revealed to act as increasing and dominant alleles as decreasing factors of the disease severity. Wr/Vr graph showed K47/2-2-1-3-3-1-1 as holding the highest number of ressecive alleles, while, K1264/1 and K74/1 holding the highest dominant alleles..

Drought stress is one of the most important environmental stresses that reduces grain yield dramatically. Grain yield results as a complex trait from contribution of many traits in plant, and evaluation of morphological traits with less complicated inheritance under different environmental conditions and related to grain yield could be used as selection criteria. To study the genetics of traits related to plant stature and flag leaf area, a cross was made between durum wheat cultivars Oste-Gata (drought tolerant) and Massara-1(susceptible). Their F1, F2 and F3 progenies were evaluated under normal and late-season drought stress using a randomized complete block design. Generation mean analysis was performed by scaling test which essays all generations simultaneously. Analysis of variance of generations showed that all traits except of width of flag leaf, differed significantly between generations. Three parametric models contain m, d and h had the best fit. Although both additive and dominance components were involved in the expression of all the traits under both environments, yet the dominance component suffered more than the additive component. Dominance variance was contributed in plant height, peduncle length and length of flag leaf more than additive variance. Therefore, these traits can not be used as selection criteria. There was no epistatic effect for the studied traits, indicating the lack of gene intractions for the traits in the segregating populations.

In order to study the genetic control of resistance to common smut in maize, two resistant inbred lines, K1264/1 and K47/2-2-21 and two susceptible inbred lines, K3304/1-2 and K47/2-2-1-3-3-1, were crossed as K1264/1 × K3304/1-2, K47//2-2-21 × K3304/1-2 and K1264/1 × K47/2-2-1-3-3-1. The F1, F2, BC1 and BC2 progenies were produced and evaluated along with parents using randomized compelet block design with three replications. All generations were artificially inoculated with spordia of Ustilago maydis suspension. Inoculation was carried out 7-10 days after silking through injection of 3 ml of 106 spores/ml fungal suspension, using tip injection method. At maturity, disease severity was determined based on ears infection and analysed according to generation means analysis method for three crosses. Joint scaling test showed that the presence of additive, dominance and epistasis effects, especially additive × additive and dominance × dominance type, and in lesser extent, additive × dominance, in genetic control of resistance to maize common smut. Average broad and narrow-sense heritability based on three crosses data were estimated 80.3 and 57.3, respectively.

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.