جستجوی مقالات مرتبط با کلیدواژه "cold" در نشریات گروه "زراعت"

In order to produce varieties of barley that tolerate drought and cold, Artan variety was entered into internal tests of the cold and temperate cold stations of the Dryland Agriculture Research Institute through the international center of ICARDA in the form of the of segregating populations (F3 generation) in 1997-98. Genetic purity was achieved by the modified bulk method. Then, during several years, it was evaluated in Maragheh, Shirvan, Ghamlo, Sararoud, Zanjan, Urmia and Ardabil stations in yield trials and yield stability experiment. The Artan variety with an average seed yield of 2.142 Kgha-1 had 11% higher seed yield than the Abidar check variety. Artan had relatively early maturity, height and high thousand-seed weight. Artan variety has general adaptability and good yield stability, facultative growth habit, resistance to seed shattering, tolerance to cold and drought, relative early maturity, high plant height (83 cm) and high thousand-seed weight (42 gr). It has also good level of resistant to yellow rust and brown rust diseases of barley. Artan variety was selected and released as a new cultivar due to its high yield and favorable agronomic characteristics for planting in the cold and moderately cold regions in rainfed areas of the country.

Studying the nature of the genotype×environment interaction provides the possibility of identifying stable and compatible genotypes for breeders, and it has always been one of the important issues in the production and release of new stable and high-yield cultivars in breeding projects. The current research was conducted with the aim of identifying the response of genotypes in each of the studied areas, based on AMMI and GGE biplot models and better understanding of the genotype×environment interaction and determining the level of public and private stability of cultivars. Twenty facultative and winter wheat genotypes were cultivated and evaluated in nine regions (18 environments) during the two crop years of 2017 to 2019 in a randomized complete block design with three replications. In order to analyze the compatibility and stability of genotypes, AMMI and GGE biplot models were used. The results of AMMI analysis showed that the main effect of genotype, genotype×environment interaction effect and the first six principal components were significant at the 1% probability level. The first and second principal components explained about 51% of the sum of squares of the genotype×environment interaction effect. Based on SSiASV and SSiWAAS simultaneous selection indices, genotypes G13, G1, G3, G2, G6, G16, and G7 were identified as the best genotypes. Biplot analysis showed that the genotypes G1, G3, and G6 with average yield had the highest general stability compared to other genotypes. None of the genotypes can be considered as desirable genotypes that have high average yield and high yield stability, but genotype G16 and in the next stage the genotypes G1 and G13 were close to the ideal genotype. Polygon biplot model divided environments into two environmental groups (macro environment) and genotypes into four groups. The first environmental group included Kar1, Kar2, Qaz1, Qaz2, Ham1, Ham2, Mia2, Egl1, Jol2, Ard2, and Ara1 environments, with G16, G17, and G4 genotypes having the highest yield. The second environmental group included Mas1, Mas2, Mia1, Ard1, Jol1, Ara1, and Egl2 environments, and in this macro environment G2, G11, G7, and G12 genotypes had the highest yield. Finally, the examination of the relationships among the environments showed a very high correlation among the investigated environments, which indicated the similar behavior of the genotypes in the most of the tested environments.

The rapid increase in the world population and the need to increase agricultural production, and on the other hand, the rapid change of climate conditions, are the significant challenges facing the world in the coming years. Wheat, the most important plant in the cereal family, plays a vital role in the world's food security now and in the future. Therefore, producing new cultivars with high yields and carefully selecting cultivars suitable for cultivation in different climatic zones are important future research priorities.

This study investigated the reaction of different bread wheat cultivars regarding yield and its components. It also aimed to study the growing degree days (GDD) and some physiological traits related to cold tolerance in different bread wheat cultivars. This study was conducted as two independent experiments during the 2013-14 cropping year at the research field, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran. The first experiment was a randomized complete block design with three replications. Treatments included 12 bread wheat cultivars (Norstar, Zarin, Kavir, Baz, Sivand, Alvand, Pishgam, Pishtaz, Orum, Shahryar, Bahar, and Parsi). The second experiment was a factorial experiment in a randomized complete block design with three replications. In this experiment, 12 bread wheat cultivars were evaluated as the first factor and sampling times as the second factor in three levels: early January, early February, early March.

The results of this study showed that Sivand and Parsi spring cultivars with the highest plant growth rate in different stages of development, with 5170 and 5100 kg/ha, respectively, and Norstar winter cultivar with the lowest plant growth rate in various stages of development, with 2230 kg/ha, had the lowest value of grain yield. The correlation between grain yield, growing degree days requirement to flowering, and physiological maturity were negatively significant. Cultivars with lower grain yield had higher growing degree day’s requirements. Examination of the growing degree days requirement of cultivars up to the flowering stage showed that, on average, spring cultivars had lower growing degree day requirements than winter cultivars. The accumulation of soluble sugars in the crown of winter and intermediate cultivars during winter was higher than spring cultivars. The accumulation of soluble sugars in the wheat crown was downward during the winter, so at the beginning of winter, the crown had a higher sugar content than in the middle and late winter. Winter and intermediate cultivars, on average, had higher leaf greenness and maximum photochemical efficiency of photosystem II than spring cultivars.

According to the results obtained in the study area, on average, winter and intermediate cultivars were superior to spring cultivars in terms of physiological traits related to cold tolerance. But, due to the obtained seed yield. However, according to the grain yield obtained in this study, spring cultivars are more recommended among cultivated cultivars than the other two growth types in Kermanshah and similar climate zones.

 Cumin is one of the most important medicinal plants in Iran and is widely used in food, health and beauty industries due to its antioxidant and antibacterial properties. Yield of some crops are higher in autumn planting compared to spring. However, low temperature and inappropriate distribution of precipitation are of factors affecting seedling emergence and establishment. So it seems that seeds with higher germination also have better emergence and establishment producing more vigorous seedlings in further growth stages. So, to success in autumn-planting of cumin, it is necessary to have ecotypes with appropriate and even emergence in low temperature and water restricted conditions. Since water is of high paramount importance in germination and lower water potentials lead to lower accessibility of water to seeds, the aim of this experiment was to study seed germination response of different cumin ecotypes to low water potentials.

This study was conducted to determine the germination of six cumin ecotypes under drought stress and low temperature conditions. Treatments comprised of six cumin ecotypes (Torbat-e-Heydarieh, Khaf, Sabzevar, Qaen, Quchan and RZ19) and seven water potentials (0, -1, -2, -3, -4, -5 and -6 bar) induced by  PEG6000 solution according to Michel B. E. and Kaufmann (1973). Distilled water was used for control. Seeds were disinfected by sodium hypochlorite (10%) and fungicide and were rinsed with distilled water. 25 seeds were placed in each petri dish and were incubated in 13°C after PEG solution or distilled water was added. Germinated seeds were recorded daily and germination percentage and rate, plumule and radicle length was determined at the end of the incubation. Ecotype ranking was also performed to determine the most tolerant ecotypes to drought stress. Statistical analysis was done using MSTAT-C and LSD test was used for mean comparison.

This study results indicated that water potentials was significantly affected all studied traits (p<0.05) in a way that germination percentage and rate and plumule and radicle length decreased as water potential decreased to -6 bar. Maximum germination percentages (61%) was obtained in control. Significant differences were also found among cumin ecotypes for all traits. Khaf and Torbat-e-Heydarieh had the highest germination percentage (25% and 23%, respectively). Decreasing water potential from 0 to the -2 bar, caused 69% decrease in germination percentage of Quchan ecotype whereas reduction of 43% and 57% was found in Qaen and Sabzevar ecotypes, respectively. Difference in germination percentage among genotypes may be due to the different water absorption by them. Ecotypes had different germination rate in water potentials (P≤0.01). Although germination rate was negatively affected by decreasing water potential, percentage of reduction was different among ecotypes in a way that Torbat-e-Heydarieh and Khaf showed the lowest (61 and 67%) and Quchan and RZ19 the highest reduction of germination rate (86%) in -4 bar compared to control (0 bar). Plumule and radical length were decreased as drought stress was increased . Decreasing water potential from 0 o -4 bar caused a 76% reduction in radical length. Significant difference was found among ecotypes according to radical length in a way that Khaf and Quchan had the highest and lowest radical length, respectively.

On the basis of ecotypes ranking for evaluated traits, Khaf and Torbat-e-Heydarieh indicated more tolerance to drought stress whereas Quchan was found as a sensitive ecotype.

One of the main production challenges of rainfed wheat is its instability. It seems that the main reasons for this instability are the weakness of genetic diversity and weak operation of agrotechnical methods causing its performance to fluctuate constantly. In order to evaluate genetic diversity and impact of the penetration coefficient of new wheat cultivars in the rainfed areas of Kurdistan province, a study was conducted by developing demonstration farms during the three cropping years 2015-2016 to 2017-2018. For this purpose, the newly released wheat cultivars were transferred to the lands in two cold and moderate cold regions in the form of demonstration farms and were evaluated along with the conventional or local cultivars using common agronomic practices based on instructions of experts. The results showed that during three consecutive years with different climatic conditions in terms of precipitation and temperature, Varan cultivar with grain yield of 1736 kgha-1 and 23% increase in yield, had a significant advantage over Sardari (local check) with grain yield of 1406 kgha-1. Other best cultivars were Baran, Ouhadi, Homa and Azar 2 with grain yield of 1664, 1549, 1496 and 1482 kgha-1, respectively, with grain yield advantages of 18, 10, 6 and 5% compared to Sardari. In moderate cold region, where Azar 2 cultivar is often cultivated, Varan, Rizhav, Ouhadi, Baran and Parav cultivars had mean grain yields of 2820, 2322, 2196, 2196 and 2193 kgha-1, respectively with 42, 17, 11, 11 and 11% increase in grain yield compared to Azar 2 as the local check cultivar with the grain yield of 1983 kgha-1. Therefore, Varan and Baran varieties are recommended for cultivation in cold regions and Varan, Reijaw (in low altitude regions), Ouhadi and Baran are recommended for cultivation moderate the cold regions of Kurdistan province.

Abiotic stresses are among major factors limiting crop yields. Cold, heat, and high-light are the most important abiotic stress among plants. Thus, it is considered the understanding of molecular mechanisms response to stress.  FtsH metallopeptidase is one of the key regulators of plant response to abiotic stresses. Many surveys were performed on the FtsH in different plants. However, there is not report on potato under cold, heat, and high-light stress.

In this study, the gene expression of StFtsH5, StFtsH6, and StFtsH10 was evaluated in root, stem, and leaves under cold, heat, and high light stresses. Agria genotypes were planted under controlled greenhouse conditions. After cold, heat, and high light treatment duration, leaves, stem, and root sampling were performed under two conditions stress and normal after 24h and 48h treatment. The relative expression of selected genes was estimated.

StFtsH5 gene was strongly up regulated in leaves and stem at the 24h and 48h under cold stress as compared to non-stress condition, respectively. Further, this gene had the higher mean relative expression than normal condition in root and leaves at the 24h and 48h under heat stress. At 24h after high light stress, the more mean relative increase StFtsH5 gene than control condition was observed. However, StFtsH6 gene is not increased gene expression under low temperature, and high light after utilization of stress treatment in leaves, stem, and root. StFtsH10 gene showed the significantly increased expression of in stem and root under high-light stress at the 48h. It showed an increase in gene expression in stem and leaves under cold stress at the 48h after stress treatment. However, this gene had the high gene expression in stem and root as compared to control at the 24h and 48h after stress treatment. The results of this study showed that StFtsH5 and StFtsH6 had the maximum and minimum gene expression in stem, leaves, and root under three stress treatments.

Among three genes, StFtsH5 showed the high expression in three tissues under cold, heat, and high-light stress. According to the above results, changes in gene expression of StFtsH5 could refer to the key roles of this gene in abiotic stresses, particularly cold, heat, and high light stresses.

Phenological, molecular and metabolite analysis during vernalization in wheat show that there is a tight relationship between vernalizatio fulfillment/reproductive transition with decrease in the accumulation of some metabolites and expression of cold-induced genes/proteins. In the present review, we will describe a number of similar protective metabolites and cold related proteins which are present or expressed in both sensitive and tolerant wheat genotypes. Based on several studies duration of cold acclimation in winter genotypes is quite higher which is influenced by developmental genes and consequently the level and duration of expression of cold-lnduced proteins is longer when compared with spring genotypes. Also, the initial rate of cold acclimation in cold tolerant winter wheat is higher than the cold sensitive genotypes. Our results show that the expression patterns of cold related proteins and metabolites are consistent with the trend of the developmental factors that have regulatory effects on proteome/metabolome. In addition, sub-zero acclimation of plants in field conditions during autumn/winter seasons has significant effects on numbers, levels and patterns of cold associated proteins in compared with plants acclimated in controlled condition at low temperature but above zero temperature. This present work, provide a novel insight to uncover the molecular mechanisms behind cold adaptation in wheat and pave the way to breed wheat for cold tolerance.

Sever coldness causes damage to the wheat and affect its growth and yield. Therefore, this experiment was conducted in controlled conditions to investigate freezing tolerance of eight wheat genotypes. Combination of temperature (+3, -3, -5, -7 and -9 °C) and genotypes (Bahar, Parsi, Pishtaz, Pishgam, Chamran, Zarin, Sivand and Marvdasht) as a factorial based on completely randomized design with three replications. Survival percentage, dry weight, number of leaves per seedling and seedling height were measured two weeks after freezing in the glasshouse. The results showed that with decreasing seedling survival due to temperature drop, dry weight, height and number of leaves in seedlings also decreased. The genotype of Marvdasht had the highest freezing resistance (-5.2 °C) was superior to other wheat genotypes in terms of dry weight, seedling height and number of leaves per seedling. Parsi and Zarin genotypes were in the next rank. While the Pishtaz genotype was a highly sensitive genotype to freezing. According to the results of this research, it can be recommended that in the regions with the probability of frostbite, it is better to avoid cultivating the Pishtaz genotype and instead use Marvdasht, Parsi and Zarin genotypes.

Identify the freezing tolerant cultivars is a suitable approach for the success of lentil sowing in autumn. In this respect, an augmented experience was carried out to evaluate freezing tolerance of 259 lentil accessions during the 2016-2017 growing seasons in Mashhad. During the growing season, the phenologic growth stages of the plants and the survival percentage affected by winter hardiness were recorded, and at the end of the growing season, morphological traits, seed yield and components were determined. The lowest recorded temperature during the growing season was -13ºC. Survival percentage varied between 0 and 100% and the highest survival percentage (100%) and maximum plant height (53cm) were found in MLC13 MLC409, respectively. Six accessions (MLC424، MLC286, MLC409, MLC303، MLC334 and MLC407) were identified as freezing tolerant. Among freezing tolerant accessions, MLC424, MLC286, MLC409, MLC303, MLC334 and MLC407 had the highest seed yield (154, 192, 220, 144, 225 and 264 g.m،2), respectively. There was a high correlation between survival percentage and seed yield and components. Based on the results, more precise assessment of physiological processes involved in freezing tolerance of lentil accessions in the controlled condition and accessing to winter hardness genotyped is necessary.

Identifying mechanisms involved in cold tolerance can play an important role in maintaining yield. In this study, physiological and biochemical responses, including malondialdehyde (MDA), cell membrane stability index (MSI), and activities of antioxidant enzymes in five autumn bread wheat cultivars and one spring tolerant cultivar in four treatments: under normal conditions (23°C), acclimation (4°C) and cold stress (-5°C) were studied in acclimated and non-acclimated wheat plants. Analysis of variance showed significant differences between the effects of cultivars and environment temperatures on the membrane stability index, while in other indices, significant differences derived between interactive effects. Results showed that lower temperatures increased MDA, while decreased MSI in different cultivars. As plants exposed to cold stress, their total protein content as well as activities of superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase increased only in cold-acclimated plants, while decreased significantly in non-acclimated strands. Results also showed lower decrease of membrane stability index and MDA in Norstar and Baran cultivars under stress conditions. It seems that in non-acclimated plants under cold stress, decrease in activity of antioxidant enzymes has impaired plant's ability to withstand stress. Therefore, a decrease in cell damages as well as an increase in capacity of cell defense systems, coming down to acclimation process, can be regarded as important factors contributing to tolerance to cold stress.

Wheat (Triticum aestivum L.) is widely grown across Central and West Asia. Evaluation of wheat genotypes in different environments is essentials to estimate Genotypes x Environment interactions (Fan et al., 2007). Breeding new cultivars require evaluation of yield stability and the adaptability of high yielding genotypes across different environments. Statistical approaches such as GGE Biplot analysis reveals genotypic main effects, as well as G × E interactions. GGE biplots analysis provides a graphical depiction of relationships among environments, genotypes and their interactions in an effective manner (Yan et al., 2000). This method has been used to examine the uniformity of different environments and to identify superior genotypes in multi-environment trials. This study aimed to determine the effects of genotype by environment interactions on the performance of 22 promising wheat lines along with two check cultivars and to identify the ideal genotypes for the examined environments.

Wheat promising lines including 22 elite lines along with two commercial cultivars Azar2 and Ohadi were evaluated in a randomized complete block design (RCBD) experiment with 4 replications under rainfed dryland conditions. Uniform experiments were carried out for 3 years (2013-16) at the agricultural research stations of Maragheh, Sararod, Ghamlo, Zanjan, Ardabil, Shirvan and Arak representing cold and moderate cold dryland wheat growing regions of Iran. Entries were planted in plots with 6 x 1.2 dimension (6-m long rows, 17.5 cm apart and seeding rate of 380 kernel/m2). Morphological characteristics, phenological stages and yield components were scored during growth period. Grain yield and thousands kernel weight were determined for each plot after harvest. The collected yield data were subjected to combined ANOVA considering environment as random and genotypes as fixed effects using SAS (9.1) statistical software. Yield stability parameters were estimated and GGE biplot analysis was carried out using open-source software R packages.

The ANOVA revealed significant differences among genotypes for yield performance. Significant genotype by environment interactions were also identified. The main effect for environments and genotypes by environment interactions accounted for 82.3 and 6.5 percent of total variances in the experiment. The grand total mean grain yield for the evaluated wheat genotypes was 2165 kg/ha. Genotypes G21 and G23 produced the highest (2378 kg/ha) and the lowest (1747 kg/ha) yields, respectively. Genotype G20 was found as the most stable according to the estimated stability parameters (Table.3).Based on polygonal GGE biplot, two environmental groups and five different groups for the examined genotypes were detected (Fig. 1). The first environmental group included Maragheh (M92, M93), Ghamlo (G92, G93, G94), Ardabil (A93), Zanjan (Z92, Z93), Arak (Ak92, Ak93, Ak94) and Shirvan (Sh93, Sh94), with the G21 being as the best performer in the group. The second environmental group included 8 remaining environments with the G1 (Azar2) as the highest yielding genotype in the group (Fig. 1). Simultaneous evaluation of genotypes for yield and yield stability identified genotypes G20, G13 G2 and G6 as high yielding with high yield stability (Fig. 2).An environment is considered ideal tester for evaluating a set of genotypes if it is able to effectively differentiate genotypes based on traits of interest and if it properly represents other environments (Yan & Tinker, 2006). Our findings revealed environments Z92, Sh92 and Ak92 as the most ideal environments and environments A92, S93, Ak92, M92, M94 as the highly discriminative of the examined genotypes (Fig.3). The genotype G20 with higher average yield and the least contribution into GxE interactions showed the characteristics of an ideal genotype (Fig. 4).

Analysis of yield data revealed that, the variations due to G × E interactions were largely explained by the environment effects. In this study, cold environments were grouped closely, showing a similar behavior in discriminating the examined genotypes and were easily distinguished from the moderate cold environments. Acute angles among environments M92, G92, Sh93, Ak93, Sh94, G94, Ak94, Z93, A93, Ak92 and also among environments S94, Sh92, M94, Z94, S92 indicated high correlations in discriminating the studied genotypes. We found the genotype G20 as the ideal genotypes possessing high yield performance and high yield stability.

Evaluating of the rapeseed genotypes under different environmental conditions would be useful to identify genotypes with stable and high yield potential. In order to study yield stability of winter rapeseed genotypes, 9 new advanced lines along with four cultivars Okapi, Ahmadi, Nima and Nafis were evaluated in a randomized complete block design in six experimental field stations including Esfahan, Hamedan, Karaj, Kermanshah, Khoy and Zarghan during 2015–2017 growing seasons. Results of combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. Cluster analysis based on the mean yield and nonparametric stability statistics showed that there were three main clusters. According to mean rank of nonparametric stability parameters, the genotypes G1, G2, G5 and G13 with the lowest value for mean rank were stable, whereas genotypes G4, G11, G7 and G9 with highest values were unstable. Also, the results indicated that the nonparametric statistics Si(3), Si(6), NPi(2), NPi(3), NPi(4) and KR were associated with mean seed yield and the dynamic concept of stability. Therefore, these methods were suitable for selecting stable and high yielding genotypes in winter rapeseed. Based on these parameters, the genotypes G13 and G2 with mean seed yield 4086 and 3829 kg h-1 respectively, were identified as high yield stable genotypes. So, these genotypes could be used for cultivation in cold and mild cold regions of the country.

Hashtrood, is a new winter bread wheat cultivar developed from evaluation of national bread wheat breeding program to cold and moderate dryland areas of Iran. New cultivar created by crossing between two advanced bread wheat lines in Maragheh research station. Hashtrood was selected from segregation populations from F2-F6 in Maragheh (2002-2007) based on its appropriate agronomic characteristics. Results of study on new cultivar in preliminary bread wheat yield trials and advanced regional yield trail in cold and moderate research stations (2008-2010) showed that, means of grain yield were 2611 and 2492 kgha-1, respectively. New cultivar was studied for 3 years (2010-2013) in ERBWYT in Maragheh, Qamlo, Zanjan, Ardebil, Sararood, Shirvan and Uromieh research stations. Based on results means of grain yield for Hashtrood, Azar2 and Ohadi were 2037, 1988 and 1970 kgha-1, respectively. Results of on-farm studies showed that means of grain yield for Hashtrood, Azar2 and Ohadi under farmer fields in East Azerbaijan were 1095, 952 and 896 kgha-1, respectively; and in Kermanshah provinces means of grain yield for Hashtrood, Azar2 and Rijaw were 1800, 1300 and 1332 kgha-1, respectively. Results revealed that Hashtrood cultivar is more tolerant to cold and drought stresses and also posses, earliness, moderate resistant to Ug99, higher 1000 kernel weight and good bread quality and therefore was released in 2015 for planting in cold and moderate cold areas of Iran.

In order to evaluate low temperature stress and the production on germination characteristics, growth parameters and photosynthetic pigments Maxima corn, experiments using as factorial a completely randomized design with three replications was conducted at Seed Science and Technology Laboratory of Faculty Agricultural Sciences, of Shahed University in 2014. Factors examined include Two of hybrid maize production MV 524 Maxima (production Iran and Hungary) and cold stress in five levels (control (no stress), zero, 2, 4 and 6 °C per Which for 2 hours in distilled water) were considered. The measured traits include germination percentage, percentage of normal seedlings, root length and shoot and seedling, relative water content, average time of germination, germination rate, chlorophyll a, band total, carotenoids and anthocyanin. The results showed that cold stress and germination of seed production and normal seedling was significant at 5% level. The production, cold stress and their interaction were significant for the percentage of photosynthetic pigments. Mean comparison showed that the highest and lowest percentage of germination was achieved in seed production and seed production in Hungary. Most of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid related to a temperature of 4°Cand maximum temperature of 2°C is the anthocyanin. The results it was concluded that control treatment (no stress) has the highest percentage of germination, seedling percentage normal and Mean germination.

Cold and freezing are the most important limiting factors on development of sensitive plants. When the ambient temperature deviates from optimal, physiological, and biochemical, metabolic and molecular changes will occur within plants. This is an effort of plants to maximize growth and developmental processes and to maintain cellular homeostasis during such adverse conditions. At the extremes of the natural temperature range of plant, the degree of physiological, cellular, metabolic and molecular dysfunction becomes so severe that it leads to death. Triazoles are the most potent groups of growth retardants with multiple effects. Plant growing with paclobutrazol generally has little effect on rates of net photosynthetic rate. However, because the compound reduces leaf area, net photosynthesis on a per plant basis is probably reduced. They have exhibited growth regulating, fungicidal, herbicidal, apicidal and antibacterial activities. More recently, it was found that triazole compounds are able to increase tolerance of plants to cold and freezing stress. Kochia (Kochia scoparia (L.) Schrad.), an out crossing species whose pollen move between plants in windy areas, has recently been considered as a forage or fodder crop in marginal lands. Steppuhn and Wall (1993) claimed that Kochia offers great potential as a crop that can be grown on saline soils, yielding fodder in quantities approaching that produced by alfalfa (Medicago sativa L.). Shamsutdinov et al. (1996) also reported more than 15 Mg ha-1 dry-matter production for Kochia under saline conditions and concluded that it is a good candidate for forage hay. Thus, the aim of the present study was to determine whether the triazole compounds could increase tolerance of kochia against freezing stress.
An experiment was carried out with hexaconazole and penconazole in 0, 10 and 20 mg.L-1 and freezing temperatures 0, -2, -4, -6 and -8 degree centigrade in factorial based on CRBD with three replications at research greenhouse of college of agriculture, Ferdowsi University of Mashhad in 2009. Plants were kept in natural condition until three weeks after planting, which in this stage they had three leaves, and then treated with fungicide. After 24 hours plants were frozen in thermo gradient freezer, in the dark. At first, the temperature of thermo gradient freezer was five degrees centigrade, and then temperature decreased two degree centigrade per hour. In order to make ice nucleation in plant at -3-degree centigrade ice nucleation active bacteria was sprayed. Plants were keeping an hour in each temperature treatment. In order to balance the ambient temperature, the plants are kept at the desired temperature for one hour and then the pots transport in a cold chamber at a temperature of 5 ± 2°C for 24 hours. The cell membrane stability was measured through electrolyte leakage (EL) and the lethal temperature 50 (LT50el) (according to El) also were determined in the youngest developed leaf from each plant. The electrolyte leakage in the solution was measured after 24 h of floating at room temperature using a conductivity meter. Total conductivity was obtained after keeping the flasks in an oven (75°C) for 90 minutes. Results were expressed as percentage of total conductivity. Survival percentage, plant height, dry weight and (LT50su) (according to survival) were determined after three weeks recovery in the natural condition. The data were analyzed statistically using a two-way ANOVA, applied to the various measured and calculated parameters, followed by a Duncan test for mean comparison between treatments at a 95 % confidence level by MSTAT-C program.
The results showed that increase of fungicide concentration by 10 and 20 mg.L-1 higher than control decreased electrolyte leakage but, electrolyte leakage build-up with decrease freezing temperature. Fungicide application increased -2 °C freezing tolerance in kochia. Increasing fungicide concentration in 10 and 20 mg.L-1 than control causes decreased LT50el from -5.9 to -7.2. Application of triazoles responsible of reduced electrolyte leakage but they did not effect on survival. The use of different concentrations of fungicides hexaconazole and penconazole of photosynthetic pigments in Kochia showed no significant effect. However, the concentration of chlorophyll a and b in the use of fungicides hexaconazole was more than penconazole.
Triazole application initially had a positive effect on the reduction of electrolyte leakage, but survival and re-growth did not affect. Generally, the use of Triazoles compounds prior to stresses such as cold, could expect the plants can tolerate oxidative stress, which usually occurs after cold stress.

The cold resistance in wheat varieties that been controlled with compatibility procedure to environment such as vernalization requirement and photoperiod reaction، has been factors for success in cold regions. Thus، knowledge of the eco-geographical distribution of influencing vernalization requirement and photoperiod reaction genes is essential for modern breeding program. To do so، 119 lines and cultivars of Iranian wheat were studied. Specific primers based on the polymerase chain reaction (STS-PCR) to identify alleles affecting the sensitivity to vernalization were used in Vrn-A1، Vrn-B1 and Vrn-D1 loci. For agro-ecological study of the diversity and distribution of these genes in Iran، data layers were prepared using GIS Map software and the latest set of tables with predominant cultivars that were cultured in each region. Results showed that spring type was 65. 5% of whole and their diversity depending on the coldness of winter. Spring type cultivars mainly adapted to south warm and moderate climates where average January temperature was above 4 oC. On the contrary، winter type adapted to areas of average January temperature from -7 oC to 4 oC. With determining genotypes based on of these traits، breeders will enable to lead segregation generations to better compatibility.

In order to evaluate cold tolerance of Lancelot Plantain plant a Factorial experiment based on completely randomized design with three replications was conducted under controlled conditions in faculty of agriculture، Ferdowsi University of Mashhad. Experimental factors include plantain ecotypes (Bojnord، Kalat، Mashhad، Ghayen and Birjand) and freezing temperatures (0، -3، -6، -9، -12، -15، -18 and -21°C). Plantain plants after 3 months growth and hardening in natural environment for applying of freezing temperatures were transferred to a Thermo gradient freezer on January20، 2012. In order to assess plasma membrane stability، electrolyte leakage percentage (EL %) and the lethal temperature 50% of plants according to the EL% (LT50el) was determined. Plant survival assessed four weeks after freezing treatment by measuring survival percentage and the lethal temperature 50% of plant according to the survival% (LT50su). Results showed that at the case of LT50el، Mashhad ecotype was the most tolerant and Kalat and Birjand ecotypes were the most sensitive ecotypes. Ecotype and temperature interactions had noticeable effects on EL and Survival percentage، so in -12 °C، Bojnord and Birjand ecotypes had the least and the most EL% respectively. In the same treatment Mashhad ecotype with 94. 4 % and Birjand ecotype with 25. 4% exhibited the most and the least survival percentage. The value of LT50su for Mashhad ecotype was 5. 3°C lower than Birjand ecotype. There was high and negative correlation between EL% and survival percentage (r=-0. 70**) in this survey. Moreover there was significant and positive correlation between LT50el and LT50su (r= 0. 53*). According to these findings، Mashhad and Bojnord ecotypes exhibited suitable freeze tolerance than Birjand ecotype.

In order to study the seed yield stability of oilseed rape lines، a series of experiments were carried out at Karaj، Kermanshah، Tabriz، Hamedan and Arak agricultural experiment stations using 10 lines، two control varieties of winter rapeseed and 3 promising lines (a total of 15 genotypes) in randomized complete block designs with three replications for two cropping seasons (2009-11). Analysis of variance showed that there was significant differences among genotypes in different environments in terms of yield. Combined ANOVA revealed significant interaction of genotype×year×location. The Lines L183، HW101، SW101، Karaj1، Karaj2 and SW103 with seed yields 4. 647، 4. 595، 4. 556، 4. 443، 4. 441 and 4. 306 (t/ha) respectively، were better than overall mean and had lower ranks and rank variance than others. Eberhart and Russell stability analysis method showed significant differences between genotypes for grain yield. Environmental variance (linear) was significant and showed a linear relationship between the genotypes in each environment with the environmental index. Genotypes L183، SW101، SW103، HW101، Karaj1 and Karaj2 with highest yield، coefficient of regression equal to unity and non-significant deviation from regression line were the most stable genotypes. Therefore، these genotypes can be used in further studies and eventually for cultivation in cold and mild cold regions.

In this research, 124 individuals of an F2 population derived from a cross between Domsiah variety (cold susceptible) and PR27137-CR153 line (cold resistant) were evaluated to identify the QTLs controlling cold tolerance in rice. Linkage map were established using 20 polymorphic SSRs and 81 AFLP markers which totally covered 3111 cM of the rice genome with an average distance of 31.67 cM. Composite interval mapping was used to determine the association between markers and traits that overall 13 QTLs were found for cold induced wilting tolerance (CIWT), cold induced necrosis tolerance (CINT), cold induced yellowing tolerance (CIYT) and cold tolerance (CT) traits. Three QTLs on chromosomes 2, 8 and 12 for CIWT, 5 QTLs on chromosomes 1, 3, 3, 10 and 12 for CINT, 3 QTLs on chromosomes 1, 2 and 8 for CIYT and 2 QTLs on chromosomes 3 and 12 for CT were mapped. Two major QTLs, qCIWT12 and qCINT12 on chromosome 12 revealed a significant contribution of phenotypic variance and also markers RM7200 and E64-M59-5 were nearly two QTLs.