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

Salinity stress is a significant factor that imposes limitations on the growth and productivity of crops. Like other living organisms, plants are susceptible to various stresses and can suffer damage when exposed to them.Under conditions of salinity stress, the stages of germination and seedling growth become particularly crucial in the life cycle of plants.Artemisia annua L., an important medicinal plant with a long history of use in traditional Iranian and other Asian medicine, was the subject of investigation in this research.The aim was to examine the impact of salinity stress on the germination process(both in terms of percentage and rate)and the characteristics of seedlings(such as radicle length,plumule length, fresh weight, and dry weight)in Artemisia annua L.The study was carried out in 2023,employing a completely randomized design with four replications at the Department of Agronomy in Shahid University.The experimental treatments consisted of four levels of salinity(0,50,100,and150 mM)induced by sodium chloride salt.The data obtained were analyzed using SAS software, and the means were compared utilizing the Duncan test at a 5%probability level.The findings of this experiment demonstrated that the control treatment(without salinity)exhibited the highest percentage and speed of germination, as well as the longest radicle and plumule lengths, and the greatest fresh and dry weights of the seedlings.Germination was not observed at concentrations of 150mM and higher.Hence, based on the outcomes of this study, it can be concluded that salinity stress has an adverse impact on the germination process and seedling growth of Artemisia annua L.,revealing the plant's heightened sensitivity to salinity.

Lentil (Lens culinaris Medik.) is one of the main food legume crops in Iran, where it is grown as a Rainfed crop in the spring season in cold regions. One of the obstacles of autumn cultivation in cold regions is the negative effects of cold and frost. So, in order to expend autumn cultivation, introducing cold varieties are needed. But until now, a cold tolerant lentil variety has not been introduced. Assessment of cold tolerance, introducing autumn cultivated cultivars and production stability are important goals of crop breeding programs in cold regions.

This study was carried out during the (2021-2022) growing season at the Dryland Agricultural Research Center. Plant materials consisted of 13 Lentil landraces that were collected from Iran and a check variety Sana. Experiments were conducted at rainfed conditions using a complete block design with two replications. Plants were evaluated for cold tolerance screening in the field under natural conditions with a cold tolerance rating (CTR: cold tolerance score) scale. observations of five randomly selected plants from each plot were recorded for plant height and seed number per plant. Green seeker calculated the normalized difference in the vegetative index using red and near infra-red light. Cold tolerance of landraces was also evaluated under controlled conditions (cold room).

According to the field trial results, none of the landraces had cold damage effects. Considering yield, NDVI index, plant height, biomass and seed number per plant, landraces 4 (Ardebil- Nir- Dash Boulagh) and 1 (Ardebil- Nir- chehre bargh) were the best. These landraces had 41% and 31% higher yields than the Sana check variety. Controlled condition results showed that landraces 2 (Ardebil- Namin- Nane Karan), 3 (Ardebil- Namin- Dodran), 9 (Varzegan- Orangh) and 11 (Varzegan- Somedel) had 91-100 survival percentage and selected as highly tolerant. Also, landraces 1 and 5 had 81.5- 82.5 survival percentages and were considered as tolerant.

Totally, results showed highly significant differences between landraces. some landraces such as number 1(Ardebil- Nir- chehre bargh) and 4 (Ardebil- Nir- Dash Boulagh), had suitable agronomic attributes and could be used in lentil breeding programs. Comparing field and controlled condition results showed accuracy of evaluating cold tolerance under controlled condition.

Allelopathy is one of the biocompatible methods to reduce the germination and establishment of weeds.In order to investigate the effect of sunn hemp extract (Crotalaria juncea) extract and oats (Avena sativa L.) on the germination of wild mustard (Sinapis arvensis), an experiment was conducted in 2022 at the Faculty of Agriculture and Natural Resources of University of Mohaghegh Ardabili University. The experiment was conducted as a factorial based on completely randomized design with three replications. The experimental treatments included the type of extract and their concentrations of zero (distilled water), 1, 5, 10, 15, and 20%. The results showed that the percentage of wild mustard seed germination and its growth components of wild mustard seeds were significantly affected by the interaction of extract type and their concentrations. The lowest percentage of germination and growth components such as plumule length, radicle length, germination speed, mean germination time, and seed germination were obtained from the concentrations of 15 and 20% of the extracts. Also, the results showed that sunn hemp extract had more inhibition on germination percentage and growth components of wild mustard seeds than oat extract. It can be concluded that with the increase in the concentration of the extracts, the inhibition of germination and the establishment power of wild mustard decreased in laboratory conditions.

In order to study the allelopathic effect of safflower genotypes on germination and seedling growth characteristics of some weed species, a factorial experiment was conducted as a randomized complete block design with 3 replications in 2017 in the research laboratory of the Faculty of Agriculture, Azad University, Sanandaj branch. The first factor included three genotypes of safflower (Wild, Sina, and Kurdistan local) and the second factor consisted of four species of weeds (grass pea, millet, berseem clover, rye-grass) and the third factor includes safflower root extract in four concentrations (0: distilled water- control, 25, 50, and 100 percent) were considered. The studied traits in this experiment included: germination speed, root length, shoot length, root fresh weight, shoot fresh weight and seed vigor. The results showed that the studied traits showed significant differences under the influence of genotype except the length of root and seed vigor. Also, all investigated traits except root length were significant under the effect of root extract concentration and weed. The results of interaction effects were also significant for most of the investigated traits. In this experiment, the Sina genotype was superior in terms of its effect on reducing the rate of germination and seedling growth, and increasing the concentration of safflower root extract reduced the rate of germination and seedling growth. Also, berseem clover and grass pea, were identified as the most sensitive and resistant plants to safflower allelopathy, respectively.

To evaluate the effect of salinity and temperature on germination, seedling growth, and ionicrelations in Castor a factorial experiment in a completely randomized design with four replications was conducted. Treatments consisted of salinity (zero, 25, 50, 100, 200, and 400 mM NaCl) and four temperature levels were 15, 20, 25, and 30 degrees Celsius respectively. In this study, germination percentage, germination rate, average germination time, root and shoot length, root and shoot dry weight, root to shoot weight ratio, shoot and root sodium, shoot and root potassium and the ratio of sodium to potassium was measured. By the increasing salinity levels, all germination indices decreased but salinity increased Root to shoot ratio and Germination time. Results showed that 20 °c had the highest germination rate, root length, shoot length, root fresh weight, shoot fresh weight, shoot dry weight, root, shoot dry weight, plant height Compared with other treatments. In this study, with increasing salinity level, the amount of shoot sodium, root sodium, and the ratio of sodium to potassium was increased. Also, the amount of potassium in roots and shoots decreased simultaneously. The temperature of 20 ° C had the lowest shoot and root mean germination time allocated shoot to root ratio and mean germination times. With increasing levels of salinity, the sodium content of shoot, root sodium, and sodium to potassium ratio was increased. Also, amount of potassium in roots and shoots increased by Increasing salinity levels, With increasing temperature amount of potassium reduced and sodium was increased

seed polishing treatment on germination and seedling growth of different sugar beet cultivars, a experiment was conducted in a completely randomized design with three replications in the laboratory and greenhouse of the Faculty of Agriculture, Shahrekord University in 2020-2021. The first factor consisted of five monogerm cultivars of sugar beet (Shokofa, Arta, Aria, Sina and Octaban) and the second factor consisted of three levels of seed polishing (control, abrasion of 10% of seed husk weight and , abrasion of 30% of seed husk weight). The results of analysis of variance showed that the effect of cultivar and the interaction of cultivar and abrasion on all traits were significant. Comparison of mean interactions showed that Aria cultivar and 30% abrasion treatment had the highest germination percentage (83.5 percentage), germination rate (7.6 seed/day), and mean daily germination (5.96 seed/day) Meanwhile, the highest coefficient of seed length vigor index (10.18) were related to Ekbatan cultivar and 30% abrasion treatment. The highest fresh weight of plumule (0.25 g) and radicle (0.053 g) belonged to Shokofa cultivar without abrasion, the highest amount of chlorophyll b (2.77 mg/g fresh weight) and related to Arta cultivar and 30% abrasion, the highest amount of chlorophyll a (4.19 mg/g fresh weight ) was observed in Shokofa cultivar with 30% abrasion In general, it can be concluded from this study that polishing of 30% weight improves the germination and growth characteristics of sugar beet seeds and among the cultivars tested, Aria is more affected by abrasion than other cultivars

Detection of resistance to an herbicide in a putatively resistant accession requires a series of experiments which are capable of illustrating the response of the accession to various herbicide doses. Whole plant bioassay in pots usually takes approx. 2 months to obtain the results, thus, rapid tests were developed to accelerate the process. Although determination of discriminating concentration as well as conduction of rapid test for some ACCase inhibitors has been performed by various researchers, no reports are available in this regard for haloxyfop-R methyl ester herbicide in winter wild oat. Thus, the following study was conducted with the objective of rapid detection of resistance to the mentioned herbicide in this weed using the rapid test.

The experiment was conducted using the seeds of 7 putatively resistant winter wild oat accessions and a susceptible biotype gathered from canola farms of Kalaleh Township located in Golestan province in 2015. Rapid test in petri dishes was conducted as a completely randomized design with three replications, with each petri dish as one replicate. To determine the discriminating concentration, various concentrations of haloxyfop-R methyl ester was applied on the susceptible accession and then, all putative accessions were screened using this concentration. The biotypes of the studied weed were exposed to various doses of the herbicide in the petri dish bioassay to determine the resistance factor. Also, a completely randomized design experiment with three replications was conducted for screening of putative accessions in the greenhouse. Accessions which maintained their survival and dry weight respectively 50 and 80 percent compared to the unsprayed control were selected. A whole plant dose-response bioassay was also done separately for each biotype.

Discriminating concentration of haloxyfop-R methyl ester for winter wild oat was obtained 0.106 mg ai. L-1. According to the results, 5 out of 7 accessions were detected as resistant and underwent the concentration- response assay in petri dishes. Resistant factors of the biotypes in the rapid test ranged from 2783.054 to 3421.414. However, no significant difference was observed among the biotypes. According to the results of the greenhouse, 5 accessions were detected as resistant with resistance factors of 14.19 to 18.54, with no significant difference among the biotypes. There was a positive and significant correlation between the results obtained from the rapid test with the greenhouse assay, which indicates the validity of the Petri dish assay.

The results of the rapid test are in accordance with those of the whole plant assay in pots. Therefore, putative winter wild oat accessions collected from the region may be screened using the obtained concentration of haloxyfop-R methyl ester (0.106 mg ai. L-1) and resistant biotypes may be detected more rapidly compared to greenhouse assays. Due to the swift development of herbicide resistance issue, rapid detection of resistance is essential. Thus, using methods such as rapid test may be very feasible.

Fenugreek, is a medicinal plant that has been considered as a salt tolerant crop. This research was conducted to investigate the effects of salt stress on seedling emergence characteristics and determination of the salt tolerance threshold, declivity of emergence and salt tolerance index of some fenugreek ecotypes.

Seeds of five ecotypes (Ardestani, Isfahani, hendi, Mashhadi, Neyrizi) were subjected to seven levels of salinity (0.5, 3, 6, 9, 12, 15 and 18 dS/m) in a factorial experiment based on a completely randomized design with three replications. In this research, experimental models (linear, sigmoidal, exponential and multi-component) were used.

Results showed that increasing levels of salinity decreased seedling emergence percentage and rate. In Ardestani and Isfahani ecotypes, increase of salinity up to 3 dS/m had no effect on seedling emergence percentage and thereafter, decreased it, significantly. The maximum seedling emergence percentage (94.62%) belonged to Hendi in control treatment. Hendi ecotype had also the highest emergence percentage (25.81%) at 18 dS/m. Although the highest seedling emergence rate (5.93 per day) belonged to Mashhadi ecotype in control treatment, it didn’t show any significant difference to Hendi, Neyrizi and Isfahani ecotypes. In Ardestani, Mashhadi and Neyrizi ecotypes, seedling length decreased significantly with increasing salinity, but this decrease was not significant in Isfahani ecotype between salinities of 3 and 6 dS/m and also 12 and 15 dS/m. In Hendi ecotype, seedling length at 3 dS/m was similar to control, but higher salinities caused a significant reduction. The maximum value of seedling vigor index (20.44) belonged to Mashhadi and Neyrizi ecotypes in control treatment and Ardestani ecotype had the lowest one (0.39) at 18 dS/m. Results showed that seedling dry weight was first unchanged up to salinity level of 3 dS/m and then gradually decreased with increasing salinity. In Hendi and Neyrizi ecotypes, applying salinities higher than 6 dS/m, gradually decreased seedling dry weight. The salt tolerance threshold of fenugreek for Ardestani, Isfahani, Hindi, Mashhadi and Neyrizi ecotypes was 4.69, 4.90, 7.83, 1.69 and 1.57 dS/m, respectively. Thus, the highest salt tolerance threshold (7.83 dS/m) and the declivity of emergence percentage (7.55%) was obtained from Hendi ecotype and the lowest one from Neyrizi ecotype (1.57 and 4.63 dS/m, respectively). Results of nonlinear models showed that the highest salinity in which  50 percent of seedlings emerged was obtained in Hendi ecotype (14.24 dS/m).

Based on the results, comparing the salt tolerance index of fenugreek ecotypes and also evaluating of some experimental models showed that Hendi ecotype may be introduced as the most tolerant ecotype to salinity stress at the emergence stage to exploit saline soil and water resources.

The aim of this study was to use the potential of productive cultivars to produce new hybrids and to evaluate the morphological and anatomical traits of hybrid seedlings between P. nigra and P. deltoides. In the present project, the male and female bases of the superior clones of Populus nigra and Populus deltoides were used, which had a high performance in terms of wood production and proper trunk quality, and were introduced to the implementation department. In winter 2018, the flowering branches of the base material with flower-bearing buds about 60–100 cm in length were collected from the end branches of the tree and planted in 20 litre plastic pots consisting of mixture of soil, sand and well-rotted cattle manure. To prepare pollen grains, a sufficient number of flowering branches were separated from the male branches of each of P. nigra and P. deltoides species and placed in a container of water and the pollen was collected by opening the male flower catkins. Pollination was achieved by lightly dusting the receptive flowers with a camel-hair brush. Catkins were collected from the branches when capsules mature and all of sterilized hybrid and open pollination capsules were cultured on Half-MS medium without hormone in the form of splitting. Produced plantlets taller than 1 to 2 cm in size were transferred to jiffypots with a mixture of sterilized perlite and peat moss and sand and kept in greenhouse and the characteristics of the percentage of contamination, height of plantlets and the number of plantlets transferred to jiffypots were recorded. The hybrid seedlings were transferred to large pots after gradual adaptation, and then they were evaluated based on quantitative traits such as height, collar diameter, branch and quantitative characteristics and anatomy of leaves after two years. The results showed that the highest catkins height, number and weight of capsules were in open pollinated cross. A total of 28 progeny were obtained from Populus different crossings. The highest stem height in crosses of PD♀xPS♂ (P. deltoides Marquette x P. deltoides Samsun) and PD♀xPB♂ (P. deltoides Marquette x P. nigra betulifolia 17/13), the maximum branch angle, leaf area and specific leaf area in open pollinated cross of PD♀ (P. deltoides Marquette) was observed.

The aim of this study was to use the potential of productive cultivars to produce new hybrids and to evaluate the morphological and anatomical traits of hybrid seedlings between P. nigra and P. deltoides.In the present project, the male and female bases of the superior clones of Populus nigra and Populus deltoides were used, which had a high performance in terms of wood production and proper trunk quality, and were introduced to the implementation department. In winter 2018, the flowering branches of the base material with flower-bearing buds about 60–100 cm in length were collected from the end branches of the tree and planted in 20 litre plastic pots consisting of mixture of soil, sand and well-rotted cattle manure. To prepare pollen grains, a sufficient number of flowering branches were separated from the male branches of each of P. nigra and P. deltoides species and placed in a container of water and the pollen was collected by opening the male flower catkins.Pollination was achieved by lightly dusting the receptive flowers with a camel-hair brush. Catkins were collected from the branches when capsules mature and all of sterilized hybrid and open pollination capsules were cultured on Half-MS medium without hormone in the form of splitting. Produced plantlets taller than 1 to 2 cm in size were transferred to jiffypots with a mixture of sterilized perlite and peat moss and sand and kept in greenhouse and the characteristics of the percentage of contamination, height of plantlets and the number of plantlets transferred to jiffypots were recorded. The hybrid seedlings were transferred to large pots after gradual adaptation, and then they were evaluated based on quantitative traits such as height, collar diameter, branch and quantitative characteristics and anatomy of leaves after two years. The results showed that the highest catkins height, number and weight of capsules were in open pollinated cross. A total of 28 progeny were obtained from Populus different crossings. The highest stem height in crosses of PD♀xPS♂ (P. deltoides Marquette x P. deltoides Samsun) and PD♀xPB♂ (P. deltoides Marquette x P. nigra betulifolia 17/13), the maximum branch angle, leaf area and specific leaf area in open pollinated cross of PD♀ (P. deltoides Marquette) was observed.

Weed seed bank in the soil is an essential source of weeds that enables them to be present in the fields. The seed bank density in a crop may reach a million seeds per square meter. Depending on the crop operation, crop rotation, and herbicide selection, the weed seed bank differs according to the location and time. Due to the economic benefits and improved crop ability, plant remains have become an attractive and acceptable way in agriculture. Allelopathic plant remnants can have a beneficial effect on weed control. The allelopathy of these plants plays a vital role in controlling the seed bank of weed soils. Therefore, this study was conducted to investigate the effect of mixing different amounts of residues of three medicinal herbs on the potential of the weed seed bank in the Malekan region.

This study was carried out at Malakan Azad University labs in 2018. Treatments included mixing different amounts of residues (0, 50, 100, and 150 g / m2), and three medicinal plants were cumin, seaweed, and marjoram. Samples had taken from a depth of 0 to 20 cm in an ocher system (7 cm radius) to measure the soil's seed bank. Weeds were isolated, and their species were identified. Laboratory studies were conducted to determine the germination strength of these seeds. This part of the experiment was carried out with three replications in a completely randomized design.

In total, 53915 weed seeds were detected per square meter. The highest seeds in the soil belonging to weed carnivorous and lambspeed were 33254 and 12457 seed per square meter of soil, respectively. The seeds of these two weeds included 95.4% of the seed bank of soil weeds. In this study, the remnants of seaweed and marigold caused a significant decrease in germination characteristics and the growth of seedlings of these weeds. Remains of cumin have little effect on the traits studied. Seed germination and seedlings growth of these weeds decreased by 44.7% and 84.9%, respectively.

By increasing the amount of application of the remains, a more significant reduction in germination and weed growth was achieved. The remnants of the two herbs had a similar effect on germination and seedling growth. Overall, this study showed that the remnants of medicinal plants could reduce the diversity and abundance of seed banks of soil weeds.

Allergic action of a plant on adjacent plants can have negative effects on their growth and development. Also, alien harmful compounds play an important role in biodiversity and the ability of ecosystems to produce.Allelopathic compounds play a major role in biodiversity and the ability to produce ecosystems. Accordingly, in this research, the effect of medicinal and essential oil of Artemisia aucheri on early germination of Medicago sativa var.blak was investigated. Clevenger was used to prepare essential oil. Factorial experiment was conducted in a completely randomized design with two factors of essential oil concentration (level 0 (control), 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm). 4 replicates of 50 seeds of the Medicago sativa var.blak were placed on two layers of Watman 42 paper inside the petri dishes with a diameter of 10 cm. Samples were placed under controlled germinator conditions with a temperature of 15-25 ° C, a relative humidity of 95%, and a light period of 8 hours of light and 16 hours of darkness. Seed counting continued until the 14th day to determine the germination characteristics and early growth of alfalfa seeds. The results showed that the highest germination percentage, germination rate, straw index, mean shoot length and mean root length were related to control treatment. In this treatment, the shortest time was 1/56 days. Germination percentage was 94% in control treatment. Black alfalfa seeds continued to sprout up to a concentration of 300 ppm. The germination rate, germination rate and indigenous index, mean shoot growth and root growth were minimized at this concentration. No germination percentage was obtained at a concentration of 500 ppm. Germination stopped completely at 400 and 500 ppm. Considering that Dashti Artemisia species has covered a wide range of rangelands in Iran, it is recommended to identify the hazardous compounds and determine their amount in these species in relation to proper rangeland management.

Seed germination is first critical and the most sensitive step in the life cycle of plants. In order to study the effects of environmental factors on germination characteristics Datura innoxia, four completely randomized design with 6 replication were conducted at Agricultural Research Bahar University, Hamedan, Iran. Salinity stress was induced by using sodium chloride (NaCl) and drought stress by using Polyethylene Glycol (PEG-6000). Five ml NaCl solution and PEG6000 (-0.2, -0.4, -0.6, -0.8, -1 MPa) were added in different petri plates. To study the effect of pH on germination, pH solutions with acidity of 4 to 9, and depth effect on seeds cultivated at depths of 0, 2, 4, 6, 8 and 10 cm. Analysis of variance of the effects of salinity and drought stress on seed germination of D. innoxia suggested that these treatments made significant changes at (P<0.05). The reduction in seed germination was proportional to the increasing concentration of NaCl and PEG. With the increasing intensity of drought and salinity from 0 to -1 MPa D. innoxia germination percentage of 100 percent respectively compared to control was reduced. Fitting of three-parameter logistic model, showed that salinity and drought stress at - 0.39 and –0.27 MPa, respectively caused 50% reduction in maximum germination percentage of D. innoxia. In addition 50% decrease in germination speed caused by salinity and drought stress, were observed in -0.33 and -0.28 MPa, respectively. The optimum pH for germination was 7 and the pH increased by decreasing the germination percentage. The highest percentage of emergence of in surface soil seeds was 73.33% and with increasing soil depth the percentage of seedling emergence decreased. Only 3% of the seeds are able to germinate from a depth of 8 cm.

This research was conducted to compare the salinity tolerance of wheat promising lines during 2015-2017. The greenhouse experiment was carried out at Seed and Plant Improvement Institute, Karaj, Iran, and the field experiment was conducted at National Salinity Research Center, Yazd, Iran. The treatments in greenhouse experiment were irrigation water salinity at two levels (2 and 14 dS.m-1) and five wheat genotypes (MS-89-13, MS-89-12, MS-90-13, MS-90-15 and Narin as check, and in the field experiment including salinity of irrigation water at five levels (2, 5, 8, 11 and 14 dS.m-1) and the same five wheat genotypes mentioned above. The results of greenhouse experiment showed that salinity stress of 14 dS.m-1 significantly decreased plant height, leaf area, shoot fresh and dry weight and root length and dry weight in all genotypes and increased chlorophyll index only in MS-89-12 genotype. Narin as well as MS-90-15 and MS-90-13 genotypes with the lowest reduction percentage due to salinity stress were determined as the most tolerant genotypes. The results of field experiment also indicated that salinity stress, depending on its severity, significantly reduced plant height, ear length, fertile spikelet number in ear, grain number per spike and thousand grain weight, which led to considerable decrease in grain and biological yield. Under control conditions (2 dS.m-1), the highest and lowest grain yield were obtained from MS-90-13 and Narin (6.91 and 5.81 t.ha-1, respectively), and under 14 dS.m-1 salinity conditions, Narin and MS-90-15 genotypes had the highest and lowest grain yield (3.23 and 1.51 t.ha-1, respectively). The threshold levels of salinity tolerance for MS-89-13, MS-90-13, MS-90-15, Narin and Ms-89-12 were evaluated to be7.41, 6.30, 4.92, 4.84 and 4.20 dS.m-1, respectively. The results showed that MS-89-13 had the higher salinity tolerance at salinity of less than 8 dS.m-1, but at higher salinity levels, Narin and MS-90-13 genotypes similar to greenhouse experiment were more tolerant than the other genotypes. According to the relatively similar results of greenhouse and field experiments, MS-90-13 line for lower salinity levels and Narin variety and MS-90-15 line for higher salinity levels were the more suitable genotypes, which could be recommended with due to considerations.

Production of nanoparticles and their use are on the rise in different areas of plant science. However, in spite of their increasing production, there is limited information about their effects on plant biology. In the current study, the potential of TiO2 nanoparticles was investigated for the purpose of improving seed germination of Sorbus luristanica and then subsequent effects of nanoparticles on the growth and biomass of the plants were determined.

Seeds of S. luristanica were collected from its natural stands. The seeds were primed with different concentrations of 0, 75, 150, 250, 350 and 500 TiO2 nanoparticles miligeram per liter for 24 h. The treated seeds were placed in wet sand at room temperature for 2 weeks and then in cold for 3 months. The expriment was set as a completely randimized design with 4 replications. Aftre 3 months of stratification in moistened sand, the stratified seeds were put in the germinator and with the appearance of seed germination signs, germination data were recorded daily during 22 days. At the end of the seed germination experiment, some germination parameters such as seed germination percentage, seed vigority and mean time to germination were calculated. Moreover, some growth and biomass parameters including leaf number, plant height and dry and fresh biomass of leaf, stem as well as roots were measured. In addition, scaning electron microscopic (SEM) was used for observation of presence and adhesiveness of TiO2 nanoparticles on the seed coat.

Based on the results, all the germination parametres including seed germination percentage, seed vigoroty and mean germination time were improved by the TiO2 nanoparticles treatments. In addition, 500 mg.L-1 treatment considerably improved seed germination characteristics. The peresence of TiO2 nanoparticles on the treated seeds and lack of the nanomatreials on the conrtol seeds were obsereved by scaning electron microscopic pictures. The One-way ANOVA showed that 75 mg.L-1 treatment was more succesful for improving the grwoth (such as shoot length) and biomass production (fresh and dry biomass of leaf, stem and root and total biomass as well).  

It can be concluded that priming of the seeds of this species with different concentrations of TiO2 nanoparticles leads to improvement of seed germination and growth and biomass parameters. However, the patterns of effects were different in each phase. Therefore, the objectives should be formulated first and then the best concentration should be chosen. It seems that with appropriate concentrations, nanoparticles can be useful for breaking seed dormancy and production of the species. Given the promising resutls of 150 mg.L-1 treatment, it can represent a successful treatment for breaking seed dormancy and seedling production of S. luristanica.
Highlights

1- Study of seed germination of Sorbus luristanica for the first time 2- Using Nano-materials and their potentials in breaking seed dormancy and improving the species germination 3- Using SEM in order to study presence and adhesiveness of nanoparticles on the seed coat

In order to take more advantage of the spring growing season, the mechanisms of germination of spring plants are of great importance at temperatures lower than the optimum temperature. Since one of the ways to reduce damage due to low temperature is enhancing the seedling antioxidant system, in this study the effects of salicylic acid and gibberellin on germination and antioxidant system of pumpkin (Cucurbita pepo) seeds were investigated under low temperatures.

A factorial experiment including four concentrations of gibberellin (0, 250, 350 and 450 mg/L), four concentrations of salicylic acid (0, 0.5, 1 and 1.5 mM) and three temperature levels (8, 11 and 14 °C) was performed with a completely randomized design within controlled conditions and six replications at Shahrekord University in 2017. The seeds were immersed in containers containing solutions of 0, 250, 350 and 450 mg/L of gibberellin and solutions with 0, 0.5, 1, and 1.5 mM salicylic acid, were placed in a growth chamber for 24 h under dark conditions at 15 °C. Then the seeds were washed at the desired temperatures, and the germination was recorded every 24 hours based on the 2 mm of radicle length. At the end of the eighth day, after the separation of normal and abnormal seedlings, 20 normal seedlings were selected from each petri dish. Following that, the germination rate, germination percentage, soluble protein, malondialdehyde, superoxide dismutase, guiacol peroxide enzyme, and catalase enzyme were measured. Comparison of means was conducted by the least significant difference test at the 0.05 probability level.

The results showed that none of the treatments used at 8 °C helped germination of the plant and, therefore, 8 °C treatment was removed from the experiment. At the temperature of 11 ° C, the use of salicylic acid 1 mM and at 14 °C, the use of gibberellin 350 mg/L showed the maximum germination rate and germination percentage, compared with the control. At 11 °C, the activity of antioxidant enzymes was more affected by gibberellin hormone so that the highest activity of superoxide dismutase enzyme was observed in 350 mg/L and the highest activity of catalase and guaiacol peroxidase enzymes and the lowest amount of soluble protein were observed in gibberellin 250 mg/L. The salicylic acid hormone was more successful at 14 ° C. The salicylic acid 1.5 mM increased the activity of superoxide dismutase enzyme; and salicylic acid 0.5 mM increased the activity of catalase and salicylic acid 1 mM improved the activity of guiacol peroxidase. This hormone also succeeded in reducing the amount of soluble protein.

In this experiment, seedling tolerance at low temperatures was confirmed by gibberellin and salicylic acid treatments. It is generally concluded that the use of gibberellin and salicylic acid increases the activity of antioxidant enzymes and, as a result, makes pumpkin (Cucurbita pepo) seedlings tolerant to low-temperature stress, and thus, can ameliorate the effect of possible chilling on growth of this crop at the beginning of the season.

Gibberellin and salicylic acid treatments make pumpkin seedling tolerant to low temperatures. Application of gibberellin and salicylic acid increases the activity of antioxidant enzymes. By using gibberellin and salicylic acid, the effect of possible chilling can be reduced at the beginning of the growing season.

Chickpea is the most important field crop among food legumes in Iran. According to the published statistic by agricultural ministry of Iran, cultivation area of chickpea varies between 550– 900 thousand hectares that more than of 90% them cultivated under dryland condition. More than 63% of country has cold and higher cold climates and more than 60% of drylands in Iran located in cold and highlands where temperature declines to -25°C in some years, with continues cold duration (more than 100 days per year). Reports show that the yield of chickpea is low in cold areas (about 500 kg.ha-1) because of the spring planting and lack cold tolerant cultivars suitable for autumn planting. In cold regions that absolute minimum temperature in winter reaches under -6°C till -12°C, studies showed that it may be complete damage occurrence if chickpea planted in autumn. Studies showed that planting of cold tolerance varieties increased the yield of chickpea almost twice. Hence, screening chickpea germplasms for cold tolerance will help to release new cold tolerant cultivars. The literature review suggests that most studies related to the evaluation and screening of chickpea cold tolerance were done under natural conditions (field), but the spatial and temporal variation in the weather under such circumstances may lead to different results. Researchers reported that using from controlled condition for screening cold tolerance genotypes in chickpea germplasm would prevent seasonal restrictions, saving time and increasing the accuracy of studies while eliminating unwanted factors. In order to study on cold tolerance of 33 Kabuli chickpea genotypes along with three controls (Saral, ILC 533 and Jam), this study carried out in square lattice design (6×6) with two replications under controlled condition (cold room) at Maragheh Dryland Agricultural Research Station, during growing season 2014-2015 . Ten seeds of each genotype after surface sterilized with fungicide (Benomile with 0.015%) planted in five cm depth in planting boxes (100×80×25 cm) at early autumn (29 September). In order to simulation of natural growth condition in autumn and acclimation of seedlings, planted boxes incubated outside of green house. Number of germinated seeds was recorded and seedling of genotypes at six-week stage, incubated in cold room. The temperature of cold room decreased two degrees in each hour up to minus 15°C and seedlings remained for one hour at this temperature. A thin layer of ice nucleation active bacteria sprayed on the surface of seedlings at -2°C in order to establish ice nucleation and prevent ultra-freezing of seedlings. Then temperature increased up to 4°C for three days and boxes transferred to green house for two weeks under 20±3°C. Frost resistance ratios (FRR) of genotypes calculated and analyzed. According to other studies and reports the genotypes with 0.91-1 and 0.81-0.90 FRR classified in highly resistance and resistance groups, respectively. Results showed that there was significant (p ≤ 0.01) differences in frost resistance ratio (FRR) among the investigated genotypes. Lines 14 (Flip98-138C* SEL99TER85074)*Sel.99th.15039, 28 (FLIP 00-84 C) and Saral cultivar had the highest FRR (100, 98 and 89 survived percentage, respectively) among the genotypes. Also Kaka cultivar and line 12 (Flip 98-28C*Flip 98-22C)* ICCV2 had the lowest frost tolerance among the studied genotypes. About 30% of genotypes could tolerate the frost damage, for example, genotypes 14 and 28 had between 0.9-1.0 ratio, whereas, the FRR of susceptible check (ILC533) was 0.13.  The existence of wide range of diversity for frost resistance among the studied germplasm would be useful to introduce new tolerant chickpea cultivars with autumn-sown potential. Moreover, the tolerance of Saral cultivar to frost stress, its cultivation under cold dryland regions could be recommended as the first frost tolerant variety in the country.

Seed germination has an important role in the life cycle of plants and critical stages of the growth cycle, establishment and final yield. Seed germination is the most critical stage of seedling establishment which ultimately determines the successful production of the product. Salinity is one of the environmental factors reducing crop production in the world. Saline soils or irrigation the plants with saline water has the potential to dramatically reduce plant production. To study the effect of different levels of salinity on the germination of 11 soybean genotypes, a factorial experiment in a Completely Randomized Design with three replications was performed in the greenhouse of Sari Agricultural Sciences and Natural Resources University in 2013. In this experiment the first factor was salinity levels (zero, 3, 6 and 8 dS.m-1) and the second factor was genotype and eight different traits including germination percentage, germination rate, root length, root fresh weight, root dry weight, shoot length, shoot fresh weight and dry weight of shoot were evaluated. Analysis of vari ance showed that the effect of salinity and genotypes in all studied traits were significant at 1% probability level. On the other hand, with increasing levels of salinity, all traits in all genotypes decreased. Also interaction of salinity and genotypes for all traits showed significant differences. In total, in the highest levels of salinity, the highest rate and percentage of germination, root length and shoot and shoot and root dry weight were achieved in tolerant genotypes of Forrest, Hill, 032, Cokerstoart and BRAZIL17, while the lowest amounts were observed in sensitive genotypes of Bau08, Mangar and 3 COH obtained.

Although early sowing the summer plants in the spring season is important for the use of moderate conditions as well as proper vegetative growth, but the incidence of low temperatures at the beginning of the growing season may be caused the problem for good establishment of seedlings. In temperate regions, chilling stress especially where early sowing was done, is very harmful for most summer plants. Seed germination is the most sensitive phase to chilling stress. Seed germination is slowed down or decreased in cold-sensitive species at temperatures below 20 °C, resulting in poor establishment and is generally prevented from germinating at temperatures below 15 °C. In order to use more of the spring growing season, improving the germination of summer plants is important at lower temperatures. Since one of the ways to reduce the low temperature damage is the upgrade of the antioxidant system of seedlings, in this study the effect of different methyl jasmonate concentrations on germination and antioxidant system of hull less seed pumpkin were studied under chilling stress. A factorial experiment was conducted in a completely randomized design under control conditions at Shahrekord University in 2017. Treatments were included six concentrations of methyl jasmonate (0, 1, 5, 50, 100 and 150 μM ) and three temperature levels (8, 11 and 14 °C). After eight days, the temperature gradually increased to reach the optimum temperature of the hull less seed pumpkin (25 ° C). On the 11 day, after separation of normal and abnormal seedlings, 20 normal seedlings were selected from each petri dish and then traits such as radicle length, plumule length, radicle dry weight, plumule dry weight, seed vigor index, soluble protein, content of malondialdehyde , superoxide dismutase enzyme activity, guaiacol peroxidase enzyme, catalase enzyme were measured. Data were analyzed by SAS V9 software. Means comparisons, were done by least significant difference (LSD) test at the 1% probability level. The results showed that the maximum radicle length (76.45 mm) was recorded at 50 μM concentration and 11 °C temperature (on an average 55.6% over the control). At 8, 11, and 14 °C, the unprimed seeds had not plumule. At 8 °C, the highest radicle length, plumule length, plumule dry weight were odserved in 5 μM methyl jasmonate. The greatest guaiacol peroxidase and catalase activity were recorded in 5 μM methyl jasmonate as well. At 11°C, the plumule length, radicle dry weight, and catalase activity in 5 μM methyl jasmonate were more than the others methyl jasmonate concentrations. However, radicle length and superoxide dismutase activity of 5 μM methyl jasmonate was second rank. At 14 °C, the highest radicle dry weight, plumule dry weight, superoxide dismutase, guaiacol peroxidase and catalase activity were obtained in 50 μM methyl jasmonate. The greatest radicle length and seed vigour were observed in in 5 μM methyl jasmonate and the in 50 μM methyl jasmonate was second rank. Methyl jasmonate, due to the polyacetylation nature at the physiological pH, can strongly adhere to the anionic position in the cellular components and cause the membrane to stabilize and thus contribute to the environmental stresses in the plant's response. Seedling tolerance to low temperatures was proved by methyl jasmonate treatments. Based on the results of this experiment, it can be said that the use of methyl jasmonate increases the activity of antioxidant enzymes and, therefore, the resistance of the seed germinator to the low temperature stress. Therefore, appllication this substance, we can modify the effect of probable fever at the beginning of the growing season.