نشریه پژوهش های بذر ایران
سال دهم شماره 1 (پیاپی 19، بهار و تابستان 1402)

Due to the fineness of parsley seeds, several problems may arise, such as the impossibility of using planting machines and the displacement of seeds by water, reduced germination and growth due to increased planting depth or lack of seed establishment in the soil, and consequently, increased seeding rate. Therefore, it is necessary to use methods to increase germination ability and improve the establishment of parsley seeds and seedlings in the soil. This experiment aimed to determine the most effective biopriming and gibberellin treatments for better germination and establishment of parsley seeds.

In order to determine the best biopriming and gibberellin priming treatments on germination characteristics and establishment of parsley seed, three experiments with four replications were conducted in the seed science and technology laboratory of Yasouj University in 2015 and 2016. The first biopriming experiment was carried out using growth-stimulating bacteria in a completely randomized design with eight treatments including bacterial isolates Pseudomonas fluorescens strain 21, Bacillus biosobetyl strain, Enterobactercus cloac strain 5, also two and three compounds of these bacteria along with control treatment. The second experiment was carried out with five treatments of Trichoderma harziarum (T36, T39, T42, and T43) isolates with control treatment. Finally, the third experiment was performed as a factorial in a completely randomized design with concentrations of gibberellin hormone (0, 50, 100, and 200 ppm) and prime times (6 and 12 hours). The measured traits were seedling length, seedling dry weight, germination percentage, and seedling length vigor index.

The results showed that the best treatments for the first experiment were biopriming with Enterobacter + pseudomonas, for the second experiment biopriming with T36 fungus strain, and for the third experiment 50 ppm of gibberellin prime for 6 and 12 hours. The results showed that the majority of biopriming and hormone prime treatments improved the quality of parsley seeds so that the germination percentage in control seeds was 70%. This value increased by 31% compared to control treatment following priming with growth-stimulating bacteria (Pseudomonas+ Enterobacter), which showed the highest rate among all treatments applied in this study. The use of 50 ppm of gibberellin priming for 6 and 12 hours increased germination by 19% and 14% compared to the control treatment, respectively.

The results of this study showed that biopriming with Pseudomonas + enterobacter had the greatest effect on improving the quality and germination characteristics of parsley seed. In general, biopriming except for T42 fungi, and also gibberellin priming showed improvement in the quality and germination properties of parsley seed.

Highlights:

1. The effects of using biopriming and hormone prime are common, while it is not clear for parsley.
2. Biopriming with Pseudomonas+ enterobacter had the greatest effect on improving the quality and germination characteristics of parsley seeds.
3. Priming with T42 fungus reduced the quality and germination characteristics of parsley seeds.

Due to the high sensitivity of seeds to damage caused by diseases or environmental stresses, germination is considered an important stage in the plant life cycle: Germination, its uniformity and emergence decline during storage due to seed vigor deterioration. Moisture stress is one of the important environmental factors affecting germination, especially during improper storage. Seed priming with gibberellic acid improves seedling characteristics in different plants under different environmental conditions. Therefore, this research aims to investigate the effect of gibberellic acid and seed deterioration on germination indices and antioxidant enzymes of safflower seeds (Carthamus tinctorius L.) under water stress conditions.

In order to investigate the effect of gibberellic acid on germination indicators and changes in antioxidant enzymes of aged safflower seeds under osmotic stress conditions, a factorial experiment was conducted in the form of a completely randomized design with four replications. The first factor includes three osmotic stress levels: zero (control), -0.4, and -0.8 MPa, the second factor includes nine aging levels (zero, 1, 2, 3, 4, 5, 6, 7, and 8 days of aging). at a temperature of 41 degrees Celsius) and the third factor included seed priming treatment at three control levels (non-priming), zero (hydro-priming), and priming with 50 mg/l gibberellic acid. A 3-parametric sigmoid model was used to show the changes in germination indices at different levels of seed deterioration.

The effect of osmotic stress, seed deterioration, and seed priming on the measured indices such as germination percentage, germination rate, seedling dry weight, normal seedling percentage, seedling length, seed germ, catalase, and ascorbate peroxidase, as well as seed protein were significant so that the measured indicators decreased with increasing seed deterioration and moisture stress. The results showed that the highest measured germination indices were obtained from seed treatment with 50 mg/l gibberellic acid under normal osmosis and non-deterioration conditions. Also, seed priming with gibberellic acid treatment caused an increase in catalase, ascorbate peroxidase, and protein activity compared to non-primed seeds under deterioration and non-deterioration conditions.

Results showed that the most suitable prime level used was gibberellic acid 50 mg/l, which had acceptable results under both stress conditions and normal conditions and deterioration and non-deterioration in comparison with other treatments. Therefore, the use of gibberellic acid hormone can help to improve germination indices as a result of changes in biochemical activities.

Highlights:
1. The effect of accelerated aging and priming on safflower seed germination under moisture stress conditions was investigated.
2.The effect of priming on catalase and peroxidase activity of aged safflower seeds was investigated.

Seed germination and emergence are the most sensitive stages of growth and development of rice plants. In this regard, the use of growth-promoting fungi in the form of seed biological pretreatment (bio-priming) for germination and optimal growth of seedlings can be feasible. Therefore, this study aimed to investigate the effect of isolated root symbiotic fungi on the improvement of germination and growth components of two traditional and bred rice (Oryza sativa L.) cultivars.

This experiment was done as a factorial-based completely randomized design with three replicates at Sari Agricultural Sciences and Natural Resources University in the summer of 2021. Experimental treatments included 22 isolates of root symbiotic fungi (isolated and identified from previous experiments) and control (without inoculation) and two native (Hashemi) and bred (Roshan) rice cultivars. After the end of the germination period, the number of normal seedlings was counted and five normal seedlings were randomly selected to measure the length of the root, stem, and seedling as well as the fresh and dry weight of the root, stem, and seedling.

Based on the results of cluster analysis the fungi were divided into four and three groups in Roshan and Hashemi cultivars, respectively. In both cultivars, group I was selected as the best group. In this group, the highest positive effect on vegetative traits varied from 5 to 59% compared to the control in fungal treatments was related to Bjerkandera adusta (ST1), Trichoderma atroviride (SF1), Monosporascus cannonballus (B3) and Trichoderma atroviride (SN1) in Roshan cultivar and Bjerkand adusta (ST1) in Hashemi cultivar. The best fungal treatments in germination traits of Roshan and Hashemi cultivars were Chaetomium globosum (SE2) and Bjerkandera adusta (ST1), respectively.

Overall, the results indicated the positive effect of most symbiotic fungi on the growth and germination characteristics of rice in both Roshan and Hashemi cultivars. These results show that symbiotic fungi use different mechanisms to increase growth and improve germination indicators in plants.

Highlights:

1- Growth-promoting fungi in the form of seed biological pretreatment were used (bio-priming) for optimal growth and germination and of rice seedlings.
2- The effect of native fungi isolated was investigated for the first time in two native (Hashemi) and bred (Roshan) rice cultivars.

The use of seed priming technology to accelerate the germination and seedling emergence of multi-purpose plants such as halophytes (Alhagi) with the ability to produce medicine and forage under environmental stress conditions or use of saline water (such as seawater of Persian Gulf) has received much attention today. Therefore, the present study was conducted to investigate seed priming methods and different salinity levels on germination, seedling emergence, and some growth responses of Alhagi plant.

Two separate split-factorial experiments were conducted based on a randomized complete block design with four replications as a petri dish culture (first experiment) and a pot experiment in the field was performed in the Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Chamran University (Ahwaz, Iran) during 2020-21. In both experiments, different levels of salinity (municipal water source with EC=0.96 dS.m-1, 8 and 16 dS.m-1 using seawater of Persian Gulf) were assigned as the main plot, and different methods of seed priming (non-priming, hydro priming, hormonal priming with 50 ppm gibberellin and hydro priming+hormonal priming with 50 ppm gibberellin) and species (A. maurorum and A. graecorum) were assigned as sub-factors.

The results showed the significance of salinity × species × priming interaction on all studied traits. According to the mean comparison results, the highest values of germination percentage, seed vigor index, seedling emergence, plant height, number of branches, total dry matter and stomatal conductance were obtained from a municipal water source with EC=0.96 dS.m-1 and hydro priming+hormonal priming with 50 ppm gibberellin for A. graecorum (29.1, 90.2, 24.0, 32.3, 52.5, 52.1 and 32.4% increase compared to non-priming and control salinity stress on this species, respectively). The output of the fitted logistic model to seedling emergence percentage showed that this model well explained the relationship between seedling emergence of two Alhagi species in responses to salinity and seed priming (R2 adj≥0.98 and RMSE≤3.38). Therefore, in both studied species, the decline in seedling emergence started from the 8 dS/m salinity level. However, at the 16 dS/m salinity level, the slope of increase in seedling emergence percentage was slower per time unit.

To cultivate and exploit the saline coastal lands and also to restore the pastures in the country, A. graecorum species under the combined treatment of hydro priming + hormonal priming with 50 ppm gibberellin are recommended in comparison with other treatment levels.

Highlights:

1- Germination and growth responses of two Iranian Alhagi species and the possibility of production by irrigation of seawater of Persian Gulf were investigated.
2- Seed priming technique was used to accelerate seedling emergence and improve some traits in two Alhagi species.

The selection of optimum planting date for every climate and mother bulb size are important factors affecting the quantity and quality of seed production in different cultivars. This study was performed in Isfahan province, Frieden, during two growing years 2016-2017 to determine the effect of planting time and mother bulb size on the quantity and quality of short-day onion seed varieties Texas Early Grano 502

A split-plot experiment was performed in a randomized complete block design with four replications. The main factor was cultivation dates at four levels: the end of August, the first of September, the end of September and the first of October and mother bulb size at three levels with 3.55, 5.5-7, and 7.5-9cm diameters were assigned as sub-plots. The measured traits were number of umbel per unit area, the number of fertilized capsules in umbel, the number of seeds per capsule, 1000 seed weight, seed yield and germination rate.

The results of combined analysis of variance showed that effect of year was only significant on the number of capsules per umbel at p<0.01. The interactions of year× mother bulb diameter and year× planting date× mother bulb diameter were not significant for any of the traits. The traits were not affected by the year. The results showed that the planting date had a significant effect on all traits except for 1000 seed weight, and the first planting date (the end of August) had the highest values in all traits. The highest germination percentage (89.83%) and the highest germination rate (12.8) were obtained on the first planting date, which showed a statistically significant difference with the subsequent planting dates. However, these two traits were not affected by mother bulb diameter treatment. The highest seed yield for onion diameter factor (505.65 kg h-1in the first year and 465.78 kg h-1 in the second year) was associated with mother bulb size of 7.5-9 cm.

The overall result showed that to obtain the highest and most desirable quality of onion seeds of Texas Early Grano 502 cultivar in Friedan of Isfahan, the planting date of the first of September and the size of the mother bulb “between” 7 to 9 cm is recommended.

Highlights:

1- Early planting time (the first of September) increased germination rate.
2- Increasing the mother bulb size increased the onion yield.

The different species of Amaranthus species are among the most important damaging weeds in the world. Due to the importance of studying the effect of management factors on seed dynamics of different weed species, this experiment aimed to investigate the effect of burial depth and high temperatures on the seed dynamic of different species of Amaranthus in Golestan province including white pigweed (A. albus), prostrate pigweed (A. belitoides), hybrid Amaranthus (A. chlorostachys), redroot pigweed (A. retrofelexus) and green Amaranthus (A. viridis) were performed.

This research was conducted on five amaranthus species of white pigweed, prostrate pigweed, hybrid Amaranthus, redroot pigweed, and green Amaranthus at the seed laboratory and greenhouse of Gorgan University of Agricultural Sciences and Natural Resources. In the first experiment, seed emergence of different species of Amaranthus was studied in eight burial depths including 0, 1, 2, 3, 4, 5, 7, and 10 cm. In the second experiment, seeds were exposed to 50, 60, 70, 80, 90, 100, and 110 °C temperatures for 5, 10, and 15 minutes

All seeds of A. blitoides and A. viridis germinated in the topsoil (zero depth); But, in A. albus, A. retroflexus, A. chlorostachys, 93%, 83%, and 3% of the seeds were emergence at the soil surface, respectively. By increasing the burial depth to one centimeter, the percentage of seeds emergence in different species of Amaranthus decreased significantly and was negligible at ≥ 2 cm depth. Germination test performed on retrieved seeds showed that zero to 16% of the seeds were able to germinate in petri dish, and most of the non-germinated seeds were viable. In all species except for A. chlorostachys high temperatures reduced the germination percentage.

Due to the reduction of seed germination percentage of different species of Amaranthus from a depth of more than one centimeter of soil, it seems that the use of conservation and conventional tillage methods has a good potential to reduce infestation of fields by these weeds. Also, although high temperatures reduce weed infestation in fields, they do not have a significant effect on depleting the seed bank of these species.

Highlights:

1- Seed dynamics of different species of Amaranthus were affected by burial depth and high temperature
2- Deep burial of seeds of different species of Amaranthus causes the stability of their seeds in the soil seed bank.

Production of high-quality seeds to stabilize crop yield is an important challenge for breeders. One of the most important answers to this challenge is to clarify the molecular mechanisms associated with seed vigor characteristics. Functional proteins of Cupin superfamily are among the molecules in signaling pathway. Previous research has shown that in maize, a storage protein similar to the functional Cupin superfamily protein called ZmGLP is effective in seed germination. However, in the previous experiments, suitable indicators were not used to assess seed vigor and its relationship with field establishment. So, it is needed to study the performance of ZmGLP in predicting field emergence to complete the previous research.

An experiment was performed on 14 samples of commercial inbred maize lines. In this experiment, in addition to the laboratory evaluation of seed germination, field indices of physiological seed quality including the percentage of seedling emergence in the field, time to 50% seedling emergence, time to 90% seedling emergence, seedling dry weight, seedling height and coefficient of variation of seedling height was also assessed. In the polymerase chain reaction, two pairs of primers (CF / CR primers and IDF / IDR primers) were used to identify the DNA sequence of the Cupin.

The results show that the seeds were different in terms of physiological quality. The lowest percentage of germination in laboratory was related to K1264/1, while the lowest physiological quality of seeds in field indices was observed in K1263/17. The molecular test confirmed the presence of the desired allele at the InDel9 site of vigor-related genes in the three samples of B73, K1264/1, and K1264/5-1, but no amplification band of the InDel9 site was observed in all K1263/17 seed samples. Due to the fact that line K1264/1, which had the lowest germination percentage in the laboratory, had an amplification band at this related site to vigor, it is not enough to rely on the results of the laboratory germination test to investigate the relationship between this gene and seed vigor. The field emergence test and seed vigor test that have a good prediction of field emergence must be used in these studies.

According to the results of this experiment, molecular tests with functional markers based on Indel9 can be used to accelerate the evaluation of vigor, especially when the breeder is breeding a new line or hybrid. It is a useful, rapid, and effective molecular method to predict seed emergence in the field and screen the lines to ensure the genetic strength of the germination of the lines, especially in the temperate germplasms of corn. Finally, it is necessary to determine the threshold of low vigor during seed quality investigation in different cultivars, and relationship between the presence or absence InDel9 site should be considered in future research.

Highlights:

1- The feasibility of using molecular markers to determine the seed vigor of corn lines in the field was studied and optimized for the first time.
2- The results of physiological quality assessment of seeds in the field for the studies related to the relationship between molecular markers and seed vigor were exploited for the first time.
3- The Indel9 site and molecular markers related to seed vigor in the field were introduced.

Salinity stress is one of the important damaging factors for seed germination which interrupts the uptake of some nutrients by lowering soil water potential and causing ion toxicity due to salt accumulation inside the seeds. Since hyssop seeds are sensitive to salinity stress in the early stages of seed germination, it is necessary to investigate seed enhancement methods to improve seed germination in this species under saline conditions. In this research, the effects of seed priming using iron were studied on hyssop seed germination characteristics under salinity stress conditions.

This research was conducted as two separate factorial experiments in complete random design with three replications. The treatments included five levels of iron nano-chelate and micro-chelate (zero, 50, 100, 200, and 400 mg /l) and six levels of salinity (zero, 50, 100, 150, 200, and 250 mM) and two priming durations. It included 12 and 24-hours.

The results showed that with the increase in salinity, the germination characteristics declined so at 200 mM of salinity, seedling growth declined significantly and ceased completely at 250 mM level. Application of iron micro-chelate under non-stress conditions did not have any positive effect on hyssop germination, and the use of distilled water for 12 hours worked better than iron nano-chelate. No significant difference was observed among the different concentrations in micro-iron treatment. Application of nano and micro chelate at 100 and 150 mM salinity stress had a stronger effect so that nano iron chelate concentrations of 200 mg/L for 12 hours and 100 and 200 mg per liter concentrations of iron micro chelate had the highest germination, seedling growth, and seed germination in 24 hours. The amount of soluble protein and peroxidase and catalase activity increased at 50 mg/L salinity but decreased at higher salinities. Also, pretreatment of seeds with an iron micro-chelate and nano iron chelate concentration of 200 mg/liter intensified this process.

The results of this study showed that seed germination of hyssop is highly declined due to salinity stress, so the seedlings were unable to grow at a salinity concentration of 200 mg/L. Moreover, germination does not occur at 250 mg/liter salinity. Also, seed pretreatment of this plant is not justifiable under non-stress and mild stress conditions, and pretreatment with iron chelate had negative effects and was ineffective at best. However, iron chelate application at high salinity levels- especially in the nanoscale with a concentration of 200 mg/liter for 12 hours- is effective in reducing the effect of salinity.

Highlights:

1- The role of the iron element was investigated by seed pretreatment method to alleviate the negative effects of salinity stress on hyssop seed germination characteristics.
2- The nanotechnology used in the production of iron fertilizer and its effect on improving the germination characteristics of hyssop under salinity stress were investigated.

Linseed (Linum usitatissimum L.) is a multipurpose crop and is cultivated to obtain oil, fiber, and seeds. Under optimal moisture conditions, the temperature is considered an environmental factor affecting the germination of this crop. Hence, knowing the cardinal temperatures can help farmers to predict the successful germination, emergence, and even yield of linseed and help scientists to develop new cultivars that are more tolerant to high temperatures. Therefore, this study was performed to determine the temperature range and the cardinal temperatures of germination in two linseed genotypes.

The germination response of two linseed genotypes (Golchin genotype and Line 286) to nine temperatures (3, 5, 10, 15, 20, 25, 30, 35, and 40 Celsius degrees) was quantified in a CRD based split-plot experiment with four replications. For this purpose, three nonlinear regression models (beta, segmented, and dent-like) were used to fit to the data and select the superior model. The superior model was selected using the Akaike information index (AIC), the modified Akaike index (AICc), and ∆i.

Findings showed that the beta model had the best performance in estimating the line 286 cardinal temperatures according to its lower AIC (-3.96), AICc (-89.61), and ∆i (0). Accordingly, the base, optimum, and maximum temperature as well as the number of biological hours estimated by this model for Line 286 were 7.18, 24.22, 40.16 Celsius degrees, and 19.25 hours, respectively. In the Golchin genotype, the beta model with the lowest AIC=-3.89 and AICc= -89.083 fitted better compared with the other models. Nonetheless, considering ∆i for beta which was respectively 0, 1.61, and 4.49 for beta, segmented, and dent-like models, Beta and segmented models had a similar accuracy in estimation of cardinal temperatures for Golchin genotype. These findings represent that the suitable temperature range for germination of the Golchin genotype is 3.8- 23.85 Celsius degrees and the range of biological hours to 50% of germination varied from 16.42 to 19.77 hours.

Overall, according to the results of this study, it is possible to predict the time to germination under optimal moisture conditions using the beta model for Line 286 and one of the two beta and segmented models for the Golchin genotype.

Highlights:

1. A suitable model was developed for a suitable prediction of the seed germination percentage of two linseed genotypes (Golchin genotype and Line 286).
2. The cardinal temperatures for two linseed genotypes (Golchin genotype and Line 286) were determined.

Weeds are one of the most important problems in agriculture and cause a lot of damage to crops. Overconsumption of herbicides in recent decades has led to harmful impacts on the environment and living organisms, including humans. In order to deal with these problems today, efforts are being made to reduce reliance on artificial herbicides and change direction towards sustainable agriculture as a part of integrated weed management. Among natural compounds, essential oils, which are components of aromatic and medicinal plants, were investigated to discover new herbicides.

In order to investigate the effects of yarrow essential oil (Achillea wilhelmsii C. Koch) on the germination and growth of purslane (Portulaca oleracea L.) and rye (Secale cereale L.) seedlings, two factorial experiments were conducted in the form of a completely randomized design in three replicates at Islamic Azad University, Science and Research Branch. The first factor was the type of essential oil in two levels (normal and nanoemulsion) and the second factor was the concentration of essential oil in six levels (0, 100, 200, 400, 800, and 1000 µl L-1).

Scanning electron microscopy images showed the particles were relatively sperhical and their size varied from 1 to 100 nm. The zeta potential of the nanoparticles was -13.8 mV, indicating particle stability. Both type of essential oils reduced germination percentage, germination rate, plumule length, radicel length and seedling dry weight of both weeds and germination percentage decreased significantly with increasing concentration. At a concentration of 200 µl L-1, purslane treated with essential oil germinated 55.25%, but at the same concentration, the germination percentage of seeds treated with nanoemulsion of essential oil was 30.50%. Nanoemulsion of essential oil at concentration of 800 µl L-1 was able to completely prevent the germination and growth of purslane seedlings. Nanoemulsion of essential oil at a concentration of 1000 µl L-1 completely prevented rye seed germination. Germination rate decreased under treatment of yarrow essential oil and there was no difference between two types of essential oils at concentration of 200 µl L-1, but at a concentration of 800 µl, the germination rate of rye seeds treated with nanoemulsion of essential oil and ordinary essential oil reached to 1.40 and 0.32, respectively which was a significant difference.

The inhibition percentage of the studied traits in both weed species showed that the essential oil nanoemulsion was more effective than the normal essential oil. Yarrow essential oil was more effective on purslane weed compared to rye. Essential oils do not have similar effects on weeds and their inhibitory effects will be different depending on the concentration and species of weeds, and the selectivity of these compounds should be investigated. The production of nano essential oil of yarrow as a natural herbicide is a solution. It offers to control weeds in organic farming systems.

Highlights:

1- Nanoemulsion particles were produced from Yarrow essential oil
 2- Nanoemulsion particles had more inhibitory effects on the investigated weeds than the normal essential oil.

Various strategies have been used to improve growth and productivity of crops through genetic approach, genetic engineering, and breeding. However, economic feasibility and ease of use can pave the way for the application of priming techniques as "stress relievers" in agricultural production. The aim of this study was to evaluate the ability of priming Catharanthus roseus seed with phytohormones of salicylic acid and Jasmonic acid under drought stress to reduce the effect of water limitation during the germination.

Two separate studies were conducted as a factorial experiment based on a completely randomized design with three replications at the Laboratory of Seed Science and Technology of Shahed University, Tehran. In the first experiment, treatments included priming in two levels of SA (0.5 and 1mM) and priming duration in two levels (24 and 48 hours), and drought stress with polyethylene glycol 6000 in 6 levels (0, 0.1, 0.5, 1, 1.5 and 2 Mpa). In the second experiment, treatments included JA (10 µM), priming duration in two levels (12, and 24 hours) and drought stress in levels six (0, 0.1, 0.5, 1, 1.5, and 2 Mpa). Dry seeds (without pretreatment) were considered as control.

In this study, drought stress treatments -1.5 and -2 Mpa in the first experiment and -1, -1.5 and -2 Mpa in the second one had no germination. Seed priming with SA and JA improved the percentage of seed germination so that in the first experiment, the highest percentage of germination (97.33) was observed under stress-free conditions with the application of 0.5 mM salicylic acid for 48 hours, which was 12.2% higher than the control treatment. 0.5 Mm of SA treatment with 24 hours of priming showed the highest percentage of germination under drought stresses of -0.1 and -0.5 Mpa. However, under drought stress conditions of -1 Mpa, 0.5 mM SA+48 hours treatment was superior compared to other treatments of salicylic acid and time. In the second experiment, the highest percentage of germination (98.3) was in the concentration of 10 μM jasmonic acid during 24 hours of priming under stress-free conditions, which showed an increase of 40.4% compared to the control treatment.

The results of the present study showed the importance of salicylic acid and jasmonic acid during seed germination stage under drought stress. Seed priming with salicylic acid alleviated the damages caused by drought stress on germination and growth. The process of adaptation to stress started by jasmonic acid can be attributed to pretreatment with jasmonic acid before applying drought stress.

The effect of priming Catharanthus roseus seeds with salicylic acid and jasmonic acid phytohormones on the germination characteristics of seeds under drought stress was investigated.
Priming Catharanthus roseus seeds with salicylic acid improved the germination percentage and characteristics of seeds under drought stress.

Althaea officinalis L. is one of the most important plants of the Malvaceae family which is used in traditional medicine and as a drug to treat the disorders of digestive and respiratory systems. The fresh seeds of Althaea do not have a good growth potential. This experiment was performed to evaluate the different methods of seed dormancy breaking on the improvement of A. officinalis L. seed germination.

An experiment was conducted in a completely randomized design with three replications at the agricultural laboratory of Payame Noor University Tehran, Shahriar Center in 2017. The experimental treatments included 10 treatments (control, seed coat removal, seed coat removal + gibberellic acid (500 and 1000 ppm), seed coat removal + potassium nitrate (0.1 and 0.2%), seed coat removal + sulfuric acid (30 and 60 minutes), sulfuric acid (30 and 60 minutes).

The results showed that the highest germination index with averages of 433.3 was observed in seed coat removal + 30- minutes of sulfuric acid treatment. The highest germination rate (44.7 seed/day) was observed in seed coat removal + 60-minute sulfuric acid treatment. The highest germination percentage (86.6%) was observed in seed coat removal+ 0.2% potassium nitrate treatment. Also, the highest mean germination time (20.2 day) was observed in both control and seeds coat removal treatments. The highest plumule and seedling length and fresh and dry weight were observed in seed coat removal + 30 and 60- minute sulfuric acid, and seed coat removal +0.2% potassium nitrate treatment, without significant difference. The highest radicle length was obtained in seed coat removal +30- minutes sulfuric acid treatment and seed coat removal + 0.2% potassium nitrate treatments.

Since all three sulfuric acid, potassium nitrate and gibberellic acid treatment along with seed coat removal treatment significantly affect the measured traits compared with control. It may be suggested that A. officinalis L. seed has a type of physical and physiological dormancy and seed dormancy breaking treatments (especially 30- minutes sulfuric acid) can be used to increase germination the fresh seeds of this plant.

Highlights:

In A. officinalis plant, removal of seed coat using chemical treatments is very effective in applying seed dormancy treatments.
 Development of A. officinalis seed cultivation and propagation is possible by applying seed dormancy breaking methods.