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Mahboubeh Shahbazi, Jafar Asghari, Behnam Kamkar, Edris Taghvaie Salimi,
Volume 10, Issue 2 (2-2024)
Abstract

Extended abstract
Introduction: The germination process is one of the most critical stages of a plant's growth and determines the success of the emergence of a weed in an agroecosystem because it is the first stage in which the weed competes for a niche. Various environmental factors, including temperature and moisture, affect the germination of weed seeds. Modeling techniques are capable of predicting germination, seedling emergence, and establishment of weed species. The ability to predict weed germination in response to environmental conditions is very effective for the development of control programs. The experiment was conducted to determine the cardinal temperature and evaluate the best model for quantifying the response of the germination rate of Western ragweed weed seeds under different water stress conditions.
Materials and Methods: A factorial experiment was conducted in the form of a completely randomized design in three replications. The investigated factors include temperature with eight levels (5, 10, 15, 20, 25, 30, 35, and 40 C˚) and water potential with six levels (0, -0.3, -0.6, -0.9, -1.2, and -1.5 MPa) on the germination of Western ragweed. In order to quantify the response of Western ragweed germination rate to temperature, three non-linear Dent-like, Beta, and Segmented regression models were used.
Results: The results showed that the effect of temperature, water potential, and their interactions on maximum germination, germination rate, and time required to reach 10, 50, and 90 percent germination were significant. Also, the results showed that by increasing the temperature from 10 to 25 C˚, the percentage and rate of germination increased whereas by increasing water potential, the percentage and rate of germination decreased. In comparing the models, based on RMSE, R2, CV, and coefficients a and b parameters, the Beta model was the most suitable for estimating the temperatures of cardinal Western ragweed. The base, optimum, and ceiling temperatures using the Beta model were 3.88, 25, and 40 C˚, respectively.
Conclusions: The use of the Beta model to quantify the germination response of Western ragweed seeds to different levels of water potential at different temperatures had acceptable results. Therefore, by using the output of these models at different temperatures, it is possible to predict the germination rate at different potentials.

Highlights:
1- Germination cardinal temperatures and the effect of water potential on western ragweed weed were investigated.
2- Estimation of different models to quantify the response of germination rate to temperature and different water potentials.

Haniyeh Saadat, Mohmmad Sedghi,
Volume 11, Issue 2 (3-2025)
Abstract

Extended abstract
Introduction: The world population is expected to increase rapidly until 2050. For this reason, it is thought that the existing lands will be insufficient for growing grains in order to meet the increasing food needs in thefuture. The decrease in agricultural lands as a result of the increase in biotic and abiotic stress factors are among the important obstacles to agriculture. Wheat, an annual herbaceous plant, is used as a basic and strategic nutrient both in Iran and in the world. Salinity is one of the major abiotic stresses that threaten global food security by impacting agricultural production, particularly in arid and semi-arid regions of the world. Seed pretreatment is a technique for minimizing emergence time, ensuring consistent germination, and improving crop performance. It is a treatment at pre-sowing, leading to a physiological condition that improve the seed to germinate. The aim of this study was to evaluate the effect of seed priming with salicylic acid on germination and biochemical traits of wheat under salinity stress.
Materials and Methods: The experiment was conducted as factorial arrangement based on a completely randomized design with four replications in a row (tube or sandwich culture) between filter paper at the laboratory of the Faculty of Agriculture University of Mohaghegh Ardabili in 2024. Experimental treatments included four salinity levels (0, 50, 100, and 200 mM) and four levels of salicylic acid (0, 0.1, 0.5 and 1 mM).
Results: The results showed that salinity stress decreased germination percentage (GP) and and increased the amount of proline and soluble sugars content, but priming with hydro, salicylic acid 0.1 and 0.5 mM especially salicylic acid 1mM improved these traits. The activity of the amount of proline and soluble sugars content in priming with 1mM salicylic acid were the application 22 and 43% higher than the control (distilled water). The activity of catalase enzyme in 1 mM salicylic acid treatment and salinity of 200 mM compared to the control showed an increase about 61%. Also the highest amount of amylase enzyme activity (4.400 mg g-1 FW min-1) was obtained in the treatment with 1 mM salicylic acid and without salinity.
Conclusions: The results of this research showed that seed priming with hydro (distilled water), different levels of salicylic acid, especially 1mM salicylic acid by stimulating antioxidant enzymes and neutralizing free radicals can be considered as a growth enhancer and reduce the adverse effects of salinity in wheat plant reduce the harmful effects of salinity stress on some traits in wheat seedlings and improve seedling growth.

Highlights:
  1. Seed priming with using distilled water, salicylic acid 1mM improved GP of seed wheat under salinity.
  2. Priming with distilled water, salicylic acid 1mM increased the activity of catalase, amylase, proline and soluble sugars content.
  3. Priming with salicylic acid showed a better effect than other treatments on germination indices and biochemical characteristics.

Kairm Dosieni, Ebrahim Gholamalipour Alamdari, Ziba Avarseji, Ali Nakhzari Moghaddam, Masoumeh Naeemi,
Volume 11, Issue 2 (3-2025)
Abstract

Extended abstract
Introduction: Borage plant (Caccinia macranthera) belongs to the family of Boraginaceae. Botanically, it is an annual, herbaceous, and wild plant. Secondary metabolites are often limited to a small group of plants within a species whose bioactive compounds, unlike primary metabolites, are found in specific organs or phenological stages of plants. Borage plant shows potent antioxidant, antibacterial and medicinal properties and it has high biomass in the arid and semi-arid regions of the eastern areas of the Golestan province. Usually, the release of allelopathic compounds from some wild plants and weeds into the environment, poses a serious challenge to the germination, morphological, and physiological characteristics of crops and even weeds. This study was conducted to evaluate the allelopathic potential of C. macranthera on germination, seedling growth, physiological, biochemical characteristics, and antioxidant activity of Pisum sativum as a plant sensitive to allelochemicals.
Materials and Methods: The experiment was carried out based on a completely randomized design with three replications in 2024. For extracting, 5 g of the whole powdered C. macranthera (by weight) was mixed with 100 mL of distilled water (by volume). Then different concentrations (i.e., 20, 40, 60, 80 and 100%) were prepared from the extract obtained from the base solution. Distilled water was also used as a control sample.

Results: The results showed that germination characteristics such as percentage and rate of germination, length of radicle, plumule and seedling, allometric coefficient, seedling length vigor index, dry weight of radicle, plumule and seedling, seedling weight vigor index in addition to the total chlorophyll pigment content of P. sativum were significantly reduced under different concentrations of C. macranthera. In contrast, the mean time to 50% germination of P. sativum increased with increasing the concentration of aqueous extract of C. macranthera. So that the difference in the effect of different concentrations of C. macranthera was dependent on their concentration threshold. This may be due to the accumulation of more harmful compounds present in the aqueous extract with increasing concentration, especially alkaloids and phenol. The physiological characteristics such as adaptive osmolytes (proline content and soluble sugars), total phenol, and antioxidant activity in P. sativum radicle and plumule had an increasing trend under allelopathic stress of C. macranthera aqueous extract. Therefore, the decrease in germination characteristics and seedling growth of pea can be related to the insufficiency of these protectors against high oxidative stress of C. macranthera.
Conclusions: Considering the demonstrated harmful effects of wild plant of C. macranthera and its high biomass in arid and semi-arid regions, especially in the east of Golestan province. It may be possible to use the bioactive compounds in this plant as an environmentally friendly herbicide. Further studies are needed to confirm its positive effects on other species before its application as a bioherbicide.

Highlights:
  1. The difference in the accumulation of allelopathic compounds of the aqueous extract from C. macranthera causes a different reduction effect in morphophysiological traits Pisum sativum.
  2. The bioactive compounds in C. macranthera can be a suitable option for the production of environmentally friendly herbicide.


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