جستجوی مقالات مرتبط با کلیدواژه « غالبیت » 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 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.

By identifying the weed seed bank can be ascertained to the composition and density of weed seed bank species and flora during the growing season and in choosing the best time and method for effective control of weed seeds in the soil was careful. Since continuous cultivation of a plant in the farm increased the seed bank of weeds, therefore, in order to describe the plant communities of the farm surface and evaluate any changes in them, it is necessary to know and study the soil seed bank. In fact, knowing the seed bank can help control future weeds on the farm and focus on better management operations. This study was conducted in order to evaluate the effect of onion monoculture continuing on weed density and diversity in the conventional agroecosystems of Jiroft region.

Weed seed bank sampling was performed from two soil depths of 0-20 and 20-40 cm by systematic random method. Density and diversity of weed seed bank were determined by germination method in greenhouse conditions. The study population were includes soil samples from four onion monoculture crops with a duration of less than three years (S1), between three to five years (S2), between five to eight years (S3) and more than eight years (S4) and long period fallow system (F). Analysis of variance of data related to different indices and comparison of different indices of diversity and richness in different onion monoculture systems were calculated by Duncan test.

At both 0-20 and 20-40 cm depths, the highest density was related to chameleon weeds. The total number of germinated seeds in greenhouse conditions in fallow and onion monoculture systems at depths of 0 to 20 was about 4140 seeds in m3 of soil that at this depth, F and S4 cropping systems had the lowest and highest number of weeds with an average of 221 and 1704 seeds in m3, respectively, and the majority of seeds were observed at this depth. At a depth of 20-40 cm, 2049 seeds in m3 of soil were observed. At this depth, S4 and F cropping systems with the average of 830 and 143 seeds had the highest and lowest number of weeds, respectively. Also, the results showed that continuous onion monoculture at both depths had a significant effect on weed diversity and species richness indices and S4 and F cropping systems had the highest and lowest diversity and richness, respectively. In fact, weed density increased with increasing continuous onion monoculture.

Because the density of weed seeds in fields under continuous cultivation is higher than fallow and a higher proportion of seeds accumulate in the surface layer of the soil. So, seed density can be reduced in the seed bank with proper rotation. Therefore, it is recommended to use crop rotations with a diverse collection of winter and spring plants instead of continuous cultivation of a crop that by increasing diversity, it provides suitable conditions for better control and interruption of weed life cycle.

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.

In order to investigate the effect of pea (Pisum sativum L.) cultivar as well as replacement and additive intercropping ratios of pea and spinach (Spinacia oleracea L.) on yield and competition indices, a factorial experiment has been conducted based on randomized complete block design with three replications at Gonbad Kavous University research field during 2016-2017. Intercropping ratios at nine levels consisted of pure pea, pure spinach, 33%, 50%, and 67% spinach instead of pea, addition series of 33%, 50%, 67%, and 100% spinach to pea. Also, pea cultivars have been Shamshiri and Pofaki. Land equivalent ratio and relative crowding coefficient in additive treatments have been more than replacement treatments, above one in all treatments. The highest land equivalent ratio with 1.333 has been observed in 100% pea + 100% spinach. In replacement series, pea has been the dominant plant, while in additive series spinach has dominated. No actual yield loss is observed in all treatments. The highest system productivity index has been related to 100% pea + 100% spinach with 3045. Overall, the land equivalent ratio of more than one and positive system productivity index of especial treatment, equal to 100% pea + 100% spinach indicate the benefit of pea and spinach intercropping.

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.

Since cucumber is one of the most economically important horticultural crops, production of hybrid seeds is very important for obtaining a profitable fruit yield. Detecting the best combination of the parents is one of the most important stages in each breeding program. By selecting parents with high heterosis in their progenies, breeders will be able to generate hybrids with high yield. This study was, thus, undertaken to examine heterosis effect on yield, yield components, and some qualitative characteristics in some fresh cucumber fruit hybrids and to select the best cross. Eighteen cucumber hybrids along with a standard national hybrid “Guilan 2” generated by VBG Company and a standard international hybrid 'PS' were planted in the Research Field of Lorestan University, Khoramabad, Iran, during 2013-2014. There were significant differences between genotypes for all measured characteristics. The mean comparison for different traits showed that B10×A4 hybrid had the highest total and marketable fruit yield and B12×A0 hybrid had the greatest early fruit yield. The greatest high parent heterosis, mid-parent heterosis and standard heterosis were belonged to B10×A11 and B10×A4 hybrids, for total fruit yield and marketable fruit yield, respectively. The greatest mid-parent heterosis and high parent heterosis were also related to B12×A0 and B10×A15 hybrids, for early fruit yield and time to first female flower appearance, respectively. Since there were notable differences between studied hybrids in terms of a number of examined traits, they can be used in crossing programs with the aim of releasing suitable hybrid cultivars.

To study the inheritance of quantitive traits in barley, crosses of barley cultivars Reyhan × Makuei and Reyhan × Kavir were studied. In each cross, parents together with F1, F2, BC1 and BC2 generations were evaluated in a randomized complete block design with three replications in research farm of Islamic Azad University, Karaj Branch. Different agronomic traits and grain yield of treatments were recorded during the growth season. The results of analysis of variance showed significant differences among generations for all traits. The generation mean analysis showed that in addition to additive and dominance, effects of epistasi were also important in inheritance of the traits. In both crosses the dominance effects were more important than additive effects for plant height, grain diameter, stem diameter, head and awn length, grain yield and 1000 grain weight. In Reyham × Makuei, for spike weight and grain number per spike, dominance effects were more important than additive effects while in Kavir × Makuei additive effects were important. The additive genetic variance was more than dominance genetic variance for traits stem diatemer, grain per spike awn and spike length and spike weight in Reyhan × Makuei, and for traits plant height, grain height, grain diameter, stem diameter, awn and pedancle length and grain yield in Kavir × Makuei. Spike weight and grain weight had the highest broad and narrow sense heritability in Reyhan × Makuei and Kavir × Makuei, respectively. Three genetic factors were determined to control the grain yield.

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.

This research conducted to investigate on effects of foliar spraying and soil split application of nitrogen on differences of dryland bread wheat varieties and genotype for nitrogen uptake, grain and straw yield. In order to do this study, experiment was conducted with factorial arrangement completely randomized block design with factor A: total, split and foliar spray applications and factor B: wheat varieties Azar2, Sardari and, Turkey 3702 genotype with three replications for three years from 2007 to 2010 in Maragheh. The results indicated that effects of urea foliar spraying, split and total nitrogen fertilizer application methods were significantly different for grain and straw yields, nitrogen uptake grain and straw of wheat varieties and genotype. Urea spraying and split method of nitrogen had highest grain and straw yields and nitrogen uptake. In addition, main effects of wheat varieties and genotype were found significantly different. Azar2 and Turkey 3702 genotype at same level increased grain yield compared to Sardari variety. Turkey 3702, Azar2 and Sardari at different methods of nitrogen application were significantly different for nitrogen content of grain. Turkey 3702 compared to other wheat varieties had heights grain nitrogen content at nitrogen split application. It can be concluded that spray and split applications of nitrogen compared to total nitrogen application can increase nitrogen content of grain and grain and straw yields. In addition, wheat genotype and varieties at nitrogen application methods can increase differently nitrogen uptake, grain and straw yields.

Intercropping or simultaneous growing of two or more crops on the same piece of land has the potential of enhanced ecosystem productivity. In a cereal-legume intercropping system, an increase in cereal and a decrease in legume intercrop yield is reported. Several indices such as land equivalent ratio (LER), relative crowding coefficient (K), competitive ratio (CR), aggressivity (A), actual yield loss (AYL) and intercropping advantage (IA) will be used to describe the competition and the economic advantage in intercropping. The objectives was to study the effect of nitrogen fertilizer and intercropping pattern on forage yield and competition indices of land equivalent ratio, relative crowding coefficient, aggressivity, competitive ratio, actual yield loss, intercropping advantage, equivalent yield and system productivity index.
Matherials and This experiment was arranged as factorial layout based on a Randomized Complete Block Design with three replications at the research farm of Gonbad Kavous University during growing season of 2011- 2012. Two factors were five planting patterns including monoculture of barley, 25, 50 and 75% pea replacement of barley and monoculture of pea and four nitrogen levels of control and 25, 50 and 75 kg N ha-1.
Sowing date was 29 Novebber 2011 and plants harvested at 26 April 2012. The traits were forage dry yield and indices of land equivalent ratio, relative crowding coefficient, aggressivity, competitive ratio, actual yield loss, intercropping advantage, barley equivalent yield of pea and system productivity index. For analysis variance of data software of SAS Ver.9.1.3 were used and treatment mean differences were separated by the least significant difference (LSD) test at the 0.05 probability level.
The results showed that monoculture of barley had maximum forage yield with 17.16 ton ha-1. By reducing for barley in intercropping ratio, forage yield was reduced so that minimum yield obtained from 25% barley 75% pea with 9.62 ton ha-1. Monoculture of pea had minimum yield with 6.71 ton ha-1. Forage yield increased by increasing of nitrogen consumption. Land equivalent ratio for total intercropping ratios were less than 1, this indicated that intercropped barley with pea was not suitable. Relative crowding coefficient, Competitive Ratio and Aggressivity for barley in intercropping ratios were greater than pea. Intercropping had not economic benefit.
Forage yield and barley equivalent yield in monoculture of barley and intercrop treatments was greater than pea. Nitrogen consumption increased forage yield and barley equivalent yield. Land equivalent ratio, relative crowding coefficient, aggressivity, competitive ratio and intercropping advantage in barley was better than pea. Actual yield loss in barley was positive and in pea was negative. system productivity y index in 25% instead of barley was higher than two other intercropping treatments.

In order to evaluate the benefits of maize, pinto bean and naked pumpkin triple cropping, an experiment was carried out as a randomized complete block design with three replications at Faculty of Agricultural Science, University of Guilan, Rasht, Iran in 2012. The treatments consisted of maize, pinto bean and naked pumpkin sole cropping (100, 75 and 50% of conventional densities), maize – pinto bean and maize – pumpkin double cropping (100-100%, 75-75% and 50-50%), and maize-pinto bean-pumpkin triple cropping (100-100-100%, 75-75-75% and 50-50-50%). The highest and lowest forage fresh weights were obtained in triple cropping system with high density and sole cropping systems with low density, respectively. In double cropping systems, the maize-pumpkin out-yielded the maize-pinto bean in terms of fresh weight. The relative crowding coefficient, competitive ratio and aggressivity of maize in double cropping of maize-pinto bean and naked pumpkin in double cropping of maize-naked pumpkin were dominant. In triple cropping systems, while maize and naked pumpkin were comparable, but both of the latter crops were dominant over pinto bean. Land Equivalent Ratio (LER) for double and triple cropping was greater than one, revealing the profitability of double and triple cropping systems on sole cropping. According to the LER, the cropping systems can be ranked as follows: triple cropping > double cropping maize/pinto bean > double cropping maize/pumpkin

Extensive and deep root system play important role in wheat drought tolerance and yield in water deficient condition. Nevertheless، a little is known about root structure genetic. In this research، a half diallel mating design was generated from crosses between eight bread wheat cultivars to study the genetic of root system. Parents and F1 progenies were planted in cyclic stress condition in a randomized complete block design with four replications and root length، root weight، root number، shoot weight، root to shoot ratio، grain yield، plant height and peduncle height were measured. Results showed that additive and dominant effects were significant for all traits. However، additive-dominant model was not adequate for root number. Non-additive variation was more important in genotypic disparity of root length and root to shoot ratio. Consequently، bulk، single seed descent and double-haploid methods are recommended in breeding program for these traits. Additive variation had imperative effect on genotypic variation of root weight and plant height. Thus، despite of mentioned breeding methods، pedigree and back-cross are recommended for these traits. Cultivar Roushan had an appropriate root system and high general combining ability for the root system traits. Accordingly، in breeding programs for developing root system، Roushan is recommended as one of the mating parents.

In order to study the phenology and competition of potato and safflower intercropping system, present study carried out in 2009 in Ardebil. Afactorial experiment was conducted in Randomized Complete Block Design (RCBD) with seven treatments and three replications. First treated to cultivate potatoes in net density of six plants per square meter fixed was allocated. Three dimensional culture treated potato mixture (with a density of six plants per square meted) and safflower densities of 6, 12, 18 plants per square meter was allocated and the other three trat ment densities of pure cultures of safflower 6, 12, 18, plants formed. The analysisof variance in pheology stages of pure culture and mixed with potatoes sheweed that all treatment were significant differences. Similary, the smaller of these indexes suggest weak competition in safflower as compared to potatoes. Ameuts of relative yield total of potatoes and safflower in all treatments intercropping was smaller than the one.

Weed identification of irrigated wheat fields in all region of Iran is the most important operation for weed management. Based on frequency of wheat fields area in each county 2500 irrigated wheat fields in all region of Iran were selected and with using a unique method the weed species were sampled and detected. With using specific formula the density، frequency، uniformity and mean density of each weed species was calculated. Geographic coordinates of fields (Latitude، Altitude and Elevation) were determined by using GPS. These information were the main coverage and were entered to a data bank. After the correcting of the information with using Arc/GIS software، and finally the weed map of irrigated wheat fields weeds were produced. There are 400 weed species that belong to 44 family in irrigated wheat fields of Iran. 74 percent of these species belong to 7 families. Polygonum aviculare Sinapis arvensis Cardaria draba، Galium tricornatum، Acroptilon repense and Descurainia sophia are the most important broad leaved weed species respectively. Avena ludoviciana،Phalaris minor، Secale cereale، Lolium rigidum، Avena fatua and Hordeum spontaneum are the most important grass weed species respectively. In addition Convolvulus arvensis، Alhagi pesudalhagi، Cirsium arvense، Carthamus oxycanthus and Glycyrrhiza glabra are the most important disturbing plants prior harvesting in irrigated wheat fields of Iran. The management of weeds in irrigated of wheat fields is not satisfy but in relative comparison the management of broad leaved weeds is better than grass weeds and the management of disturbing plants prior harvesting is in the lowest level.

Diallel crosses of eight genotypes of safflower were conducted and F1 and F2 generations were evaluated to estimate genetic parameters for seed-quality related traits including protein contents (%), fiber, ash and oil yeild. Griffing’s methods 1 and 2 for F1 and F2 generations was used, respectively. Sixty four genotypes including 8 parents and 56 F1 progenies, and half diallel crosses of F2 generation were grown using a complete randomized block design. Results of analysis of variance based on Griffing’s method revealed significant general combining ability (GCA) and specific combining ability (SCA) of all studied traits in F1 and F2 generations, implementing the importance of additive and non-additive genetic effects. Significant reciprocal mean squares were estimated by Griffing’s method indicated the importance of cytoplasmic genetic factors for controlling oil yield. Low narrow sense heritability estimates and high estimates of dominance effects for ash content indicated the importance of non-additive genetic efficiency for it. Hence the efficiency of hybrid production method would be high to improve it. High narrow-sense heritability estimates and high degrees of additive effects for oil yeild and fiber indicated the prime importance of additive genetic effects for these traits, therefore, the efficiency of selection would be high to improve these traits. The estimates of genetic variance components proposed the importance of both additive and dominance genec effects which contribute to variation in protein content.

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.

Seven rice varieties (Hassani, Deilmani, Sepidruod, Shahpasand, Saleh, Neda and IRFAON215) and their complete diallel progenies were grown in a randomized complete block design with three replications in the growing seasons of 2006 and 2007 at the Rice Research Institute of Iran (RRII) in Rasht. Genetic components, the mode of inheritance and heterosis of various physiological traits were studied by using seven-parent diallel mating design including reciprocals. Results revealed that both additive and non-additive gene effects were important for inheritance of days to flowering, plant height and panicle exsertion with preponderance of additive gene effects. Inheritance of harvest index was controlled only by additive effects. While, inheritance of grain yield, panicle length and flag leaf area were governed by non-additive gene effects. ‘F’ value, showing an excess of dominant alleles in the parents, was significant only for grain yield. The average degree of dominance (H1/D) 0.5 was within the range of partial dominance for days to flowering, plant height, panicle exsertion and harvest index. At least two major groups of genes controlled the inheritance of plant height, and panicle length and flag leaf area, four major groups the inheritance of harvest index and one group the inheritance the other traits. The highest value of relative heterosis was observed for panicle exsertion and grain yield. Wr-Vr graphic analysis indicated that increase of flag leaf area, plant height, panicle exsertion and panicle length was under the control of dominance alleles, but harvest index was increased by recessive alleles. Due to the importance of non-additive components for grain yield, panicle length and flag leaf area, biparental mating and/or reciprocal recurrent selection could be used for genetic improvement of these characters. Predominance of additive effects for remainder of the traits demonstrated that breeding methods based on selection may be advantageous in improving of these traits in rice using the studied materials.