Iranian Journal of Seed Research

In order to evaluate the electrical conductivity and seedling growth characteristics of red bean seed grown under drought stress and foliar application of zinc and manganese, a split factorial experiment was conducted in a Randomized Complete Block Design in the field and also laboratory experiment at Shahrekord University in 2011. Factors included three levels of drought stress (irrigation after 50, 70 and 90 mm evaporation from class A pan) as the main plot and three levels of zinc foliar application (with water, 100 and 200 grams per hectare zinc), and three levels of manganese foliar application (with water, 150 and 300 grams per hectare manganese) in a factorial combination as subplot. The results showed that severe drought stress led to decrease of electrical conductivity while the seedling and root length of red bean seed were increased. In the measured characteristics, Mn foliar application had a significant effect on electrical conductivity and root dry weight. In different Mn foliar application treatments, the lowest electrical conductivity was related to control while the maximum seedling dry weight was observed at 150 g Mn foliar application per hectare. Zn foliar application had a significant effect on all the traits measured during this experiment. Based on means comparison, the highest seedling dry weight, shoot, seedling and root length, as well as the lowest electrical conductivity, belonged to the 100 g Zn foliar application per hectare. The highest root dry weight was obtained for 200 g Zn per hectare which no significant difference was observed with 100 g Zn per hectare. According to the results of this experiment, mild stress and foliar application of zinc and manganese led to increasing the quality of the produced seeds. In total, foliar application of zinc and manganese (at the amount of 100 and 300 g ha^-1 respectively) with mild stress (irrigation after 70 mm evaporation from class A pan) are recommended for the production of seeds with high vigor under this region conditions.

Extended abstract
Introduction: Quinoa, with the scientific name (Chenopodium quinoa Willd), belongs to the Spencer family. Seeds vigor can be improved with a variety of seed priming methods. In this method, the seeds are soaked in water or various osmotic solutions and then dried to the original moisture. After priming treatment, seeds are stored and cultivated as untreated seeds. Potassium nitrate is the most frequently used chemical for the purpose of increasing seed germination and is recommended by the Society of Official Seed Specialists and the International Association of Seed Testing for germination experiments of many species. In recent years, the use of nanoscale materials has been of great interest to researchers. Chitin, one of the most abundant polysaccharides in nature, is a polymer chain of N-acetyl glucosamine and is associated with other proteins and other organic compounds, and numerous industrial, pharmaceutical and agricultural applications have been reported for it. The present study was carried out to investigate the effects of chitosan nanoparticles and potassium nitrate on some morphological characteristics, germination characteristics, chlorophyll content and relative humidity of quinoa plant.

Materials and Methods: In order to investigate the effect of pretreatment of quinoa seeds with chitosan nanoparticles and potassium nitrate solution on the early stages of germination, a factorial experiment was conducted in a completely randomized design with four replications in Seed Processing Laboratory, Faculty of Agricultural Sciences and Natural Resources, Shahed University, Tehran, Iran. Experimental treatments consisted of priming with chitosan nanoparticles in 4 levels (no primers, 0.01, 0.20 and 0.04% w / v) and potassium nitrate in 3 levels (no primers, 0.2 and 0.5% Weight percent) and hydroperime for 2 hours at 25° C. For each replicate of every treatment 100 seeds, using standard priming methods, were treated with the materials mentioned above and were dried in a petri dish on Watman paper No. 1 at 20 ± 1 ° C and relative humidity of 70% and 16 hours of daylight and 8 hours of darkness to make germination work. After that, germination percentage, root length, shoot length, germination coefficient, Allometric coefficient, relative water content, chlorophyll content a and b were measured, using standard methods.

Results: Seed treatment with 0.2% potassium nitrate solution increased germination by 9% and treatment with chitosan 0.01% increased germination by 14%, compared with the non-primer treatment. The priming treatment with a 0.5% solution of potassium nitrate and 0.01% chitosan increased germination by 36%, compared to the non-primer treatment. Potassium nitrate increased root length by 25% and shoot length by 10%. In addition, chitosan 0.01% increased the root length by 6%, and seeds with chitosan 0.02% and potassium nitrate 0.2% increased the root length by 32%. The effects of potassium nitrate, chitosan and their interaction on chlorophyll a and b were significant at 1% probability level. The highest levels of chlorophyll a were obtained in 0.02% chitosan and 0.2% potassium nitrate. This formulation increased the chlorophyll a content by 33%. The highest amount of chlorophyll b was obtained by applying 0.01% chitosan and 0.5% potassium nitrate.

Conclusion: The results of this study showed that treatment with 0.01% w/v chitosan and 0.5% w/v potassium nitrate resulted in the highest germination percentage, chlorophyll content a and b, relative water content, and stem length. Treatment with 0.02% chitosan and 0.2% potassium nitrate resulted in the highest allometric coefficient and root length.

Extended abstract
Introduction: London rocket is an important winter annual weed of the mustard family (Brassicaceae), which is propagated by seed. Germination of a seed population in response to water potential reduction is modeled using the concept of hydro time. This model has outputs that are physiologically and ecologically meaningful. One of the presumptions of the Hydro time model is the normal distribution of the base water potential among the seed population.
Materials and methods: In order to quantify the germination characteristics and determine the cardinal temperature of germination of London rocket (Sisymbrium irio L.), an experiment was done in 2018 at Science Research Branch, Islamic Azad University, Tehran, Iran. The seeds were placed at constant temperatures (5, 10, 15, 20, 25, 30, 35, 40 and 45 °C). Germination percentage, germination rate, root length, shoot length, seedling length and seedling fresh weight were evaluated. Intersected-lines, dent-like and quadratic polynomial models were used to determine cardinal temperatures. London rocket seed germination was tested across a range of water potential (0, -0.2, -0.4, -0.6 and -0.8 MPa) at the optimal temperature of 22.80 °C. The hydro time model, based on the normal distributions was fitted to data.
Results: Results showed that seed of London rocket did not germinate at temperatures of 5, 35, 40 and 45° C, and 25° C was the best temperature for seed germination (48%). The longest root length (4.49 mm) was observed at 20°C, which did not have significant differences with temperatures of 15 and 25 °C. The longest shoot length (10.19 mm) was obtained at 25 °C and there were not any significant differences among this temperature and temperatures of 15 and 20 °C. Similar trend with the trait of root length was observed for the trait of seedling length. The best model for estimating the cardinal temperatures in London rocket was intersected-line model with respect to coefficient of determination and mean square error. According to the intersected-lines model in London rocket, the minimum, optimum and maximum temperatures were calculated 5.83, 22.80 and 37.91°C. According to the hydro-time model based on normal distribution, the hydro-time constant and the base-water potential (which is a threshold for germination beginning) of London rocket degree were 284.28 (MPa/h) and -1.18 (MPa) at 22.80 °C, respectively.
Conclusions: Knowledge of germination and emergence of weeds also helps to predict the potential distribution to new habitats. The obtained coefficient of determination (0.94) between observed germination and predicted germination showed that the hydro time model based on normal distribution fitted well to germination percentage of London rocket seed. Due to the low hydrotime coefficient of this weed and the drought problem that most provinces face, it is expected that this weed will become more problematic in most provinces of Iran in the future.
 
Highlights:
1- The best temperature for germination of London rocket seed is 25 °C.
2- The best model for estimating the cardinal temperatures in London rocket is intersected-line model
3- The hydro-time constant and the base-water potential of London rocket degree based on normal distribution are 284.28 (MPa/h) and -1.18 (MPa) at 22.80 °C, respectively.

Extended Abstract
Introduction: It is obvious that all plants adopt mechanisms to control NaCl accumulation because sodium chloride is the most soluble and most abundant salt. Binweed (Convolvulus arvensis L.) is among the ten widespread noxious weeds in the world that it is reproduced by seed, horizontal lateral root, and rhizome. Because of the extensive underground root system of the bindweed with abundant buds and established root reserves, binweed competes more tolerant than crops under salinity and drought stress. More information on morphophysiological traits of binweed under salinity conditions and comparison of salinity tolerance index between germination and seedling can also be contributed to the most effective management. In order to investigate the germination and seedling growth characteristics of binweed two experiments were conducted separately under salinity stress.
Materials and Methods: Germination experiment was done in a completely randomized design with 9 levels of salinity stresses include 0 (control), 5, 10, 15, 20, 25, 30, 35, and 40 dS.m^-1, with four replications in the lab. The seedling experiment was performed in a random complete block design consisted of five levels of salinity (tap water, 10, 20, 30, and 40 dS.m^-1) with three replications as the pot in a non-shade greenhouse of Agricultural College of Shahid Chamran University of Ahvaz.
Results: The results showed that with raising salinity, percentage germination and vigure index of seed declined, but Radicle/ Plumule ratio rose. After two weeks, in response to salinity a decrease in root and shoot characteristics of the seedling was observed. Salinity stress data were fitted to a three-parameter logistic for seedling stage showed that the salinity levels higher than 7.86 dS.m^-1 led to 50 percent reduction in tolerance index. It was found that 19.84 dS.m^-1 caused 50% decrease in the tolerance index at germination stage. Sufficient tolerance index –growth stage variation in response to salinity was found which suggests that bindweed tolerance to salinity at germination stage is about 3 times more than that of seedling stage.
Conclusions: Radicle/ plumule ratio at germination stage and root lateral branches at seedling stage increased in concentrations of up to 25  and 20 dS.m^-1, respectively. It seems the maintenance of root area and branches in response to increased salinity provide an acceptable mechanism of salinity tolerance for binweed. According to the three-parameter logistic model, the salinity tolerance of bindweed at germination and seedling stages was estimated at 20 and 8 dS.m^-1, respectively.
Keywords: Logistic model, Root lateral branches, Relative water content, Salinity tolerance index
Highlights:
1 Salinity tolerance of bindweed was investigated in germination and seedling growth.
2- Salinity tolerance index was compared between germination and seedling of bindweed and was introduced a proper trait which is more effective to pointing salinity tolerance.
3- The best sigmoidal model based on salinity criterion was introduced for salt tolerance index of bindweed.