Ali Tavili; Hamed Eskandari Damaneh
Volume 28, Issue 1 , April 2021, , Pages 93-105
Abstract
Seed germination is usually the most critical factor in determining the success or failure of plant establishment. The most important environmental factors affecting germination, establishment, and growth of plants are temperature and humidity, which have significant effects on germination characteristics ...
Read More
Seed germination is usually the most critical factor in determining the success or failure of plant establishment. The most important environmental factors affecting germination, establishment, and growth of plants are temperature and humidity, which have significant effects on germination characteristics such as germination percentage and rate. For this purpose, to determine the cardinal temperatures of seed germination in Ziziphus spina-christi, in vitro experiment, the germination characteristics of the seeds of this plant at different temperatures were evaluated in a completely randomized design with four replications. Germination response was assessed at the constant temperatures of 5, 10, 15, 20, 25, 30, 35, 40, and 45°C. The cardinal temperatures for the germination of Ziziphus spina-christi seeds were fitted using germination rate and by three models including the beta, segmented, and dent-like models. To select the superior model and measure the accuracy of the model in describing the germination rate of Ziziphus spina-christi seeds for temperature, the statistics of root mean square (RMSE) and coefficient of determination (R2) were used. Accordingly, a higher R2 and a lower RMSE represent a closer correlation of the model with reality. Based on the results, these statistics were better for the segmented model than the other models, so that they were 0.0004 and 98% for this model, respectively. Therefore, based on the segmented model, which was known as the superior model, the basal temperature, the optimum and maximum germination rate of this plant were calculated to be 8.6, 34.3 and 49 ° C, respectively. Then, the response of germination and seedling growth of Ziziphus was explored in another experiment to different levels of salinity and drought stresses at the optimum temperature. In this experiment, the seed germination was studied at four levels of salinity and drought stresses with osmotic potentials of 0, -2, -4, -6, -8, and -10 bars. The results of this experiment showed that salinity and drought stress reduced the germination percentage and rate of Ziziphus spina-christi seeds. Germination percentage for control was 97% while in -10 bar salinity and drought stress was 16% and 0, respectively. In addition, compared to drought, seed germination showed more sensitivity to salinity stress.
Sedigheh Zarekia; Ali Ashrar Jafari; Ehsan Zandi Esfahan; Leila Fallah Hosseini
Volume 20, Issue 1 , June 2013, , Pages 88-100
Abstract
To investigate the germination of perennial herbaceous Astragalus, six species in different accessions were selected to be studied in a randomized complete block design in which three treatments including control, scarification and chilling were applied for one week with three replications. The study ...
Read More
To investigate the germination of perennial herbaceous Astragalus, six species in different accessions were selected to be studied in a randomized complete block design in which three treatments including control, scarification and chilling were applied for one week with three replications. The study was carried out in the laboratory of Gene Bank at RIFR. Germination percentage, germination rate, plumule and radicle lengths, vigor index and ratio of radicle to plumule length were measured. All data were analyzed and the studied species showed significant differences in terms of the mentioned germination parameters except radicle length and ratio of radicle to plumule while differences among treatments were significant for all traits except radicle length. Interaction effects of species*treatment were also significant except radicle length and vigor index. Maximum and minimum values of germination traits were recorded for A. vegetus and A. lilacinus, respectively and other species were classified as average. The values of germination traits in chilling treatment were less than that in control treatment and it can be concluded that the cultivation of these species in autumn and winter may cause unsuccessful establishment. According to the results, A. vegetus was identified as a suitable species for range improvement in terms of most germination traits.
Samira saburi rad; Mohammad Kafi; Ahmad Nezami; Mohammad Bannayan Aval
Volume 18, Issue 4 , September 2012, , Pages 578-592
Abstract
Kochia(Kochia scoparia)is an annual halophyte and drought resistant plant that can be irrigated with saline water and has the capability of being used as a valuable source of forage in ecosystems under drought and salinity stress. In order to evaluate germination characteristic of Kochia scoparia under ...
Read More
Kochia(Kochia scoparia)is an annual halophyte and drought resistant plant that can be irrigated with saline water and has the capability of being used as a valuable source of forage in ecosystems under drought and salinity stress. In order to evaluate germination characteristic of Kochia scoparia under different temperatures and water potentials, an experiment was conducted in 2009 at Physiology Lab of Ferdowsi University of Mashhad. Experiment was conducted in a completely randomized design with 4 replications. Treatments included 9 levels of water potential (-0.25,-0.5, -0.75.-1, -1.25,-1.5,-1.75 and -2 MP) and also the treatment not exposed to drought (control) and 8 temperature levels (5, 10, 15, 20, 25, 30, 35 and 40 0C). The results of variance analysis showed that different levels of temperature and water potential had a significant effect (P<0.01) on germination percentage, germination rate, mean germination time and germination index. Interaction effect between temperature and water potential on the mentioned parameters was also significant. The highest percentage of germination occurred at 20-250C and 4 primary levels of water potential with no significant differences between each other. Also, the highest germination rate occurred at 250C and in control treatment. With decrease of water potential, germination rate also decreased in all temperature treatments. In addition, decrease in water potential caused an increase in mean germination time. The lowest mean germination time was observed at 250C equivalent to 1.07 day. The highest germination index occurred at 250C and in control treatment. However, seeds of Kochia are able to germinate in a wide range of temperature and water potential.
fahimeh Arab; Ali- Ashraf Jafari; Mohammad- Hassan Assareh; Mohammad Jafari; Ali Tavili
Volume 18, Issue 1 , May 2011, , Pages 17-31
Abstract
Agropyron deserterum andAg. elongatum species have a high value for both fresh and dry forage and because of high production and top acceptance by livestock they have specific value in the beginning of the growth season for livestock grazing. This research was conducted to study the effects of ...
Read More
Agropyron deserterum andAg. elongatum species have a high value for both fresh and dry forage and because of high production and top acceptance by livestock they have specific value in the beginning of the growth season for livestock grazing. This research was conducted to study the effects of salinity stress on the mentioned species in germination and vegetative growth stages. A completely randomized design including five levels of 0, 100, 200, 300 and 400 mM NaCl and CaCl2 with 4 replications was used. Seeds were sown in laboratory and germination percentage, germination velocity, vigor index, plumule and radicle length and seedling dry weight were calculated. In greenhouse condition, shoot and root length, seedling dry weight, dry weight to fresh weight ratio, leaf area and specific leaf area were measured. According to the results, in both studied species germination percentage, plumule and radicle length, seedling dry weight, leaf area and specific leaf area were reduced with increase of salinity. The results showed significant differences between two species for germination percentage and germination velocity (P≤0.01). In both germination and vegetative growth stages, Ag.elongatum was more salt tolerant than Ag.desertorum. The results indicated that Ag.elongatum was more salt tolerant species than Ag.desertorum and it can be recommended for cultivation in moderate saline rangelands.
Hamid reza Mehrabi; Mohammad reza Chaichi; Reza Tavakolafshari; Hasan Madah Arefi; Ghavamodin Zahedi Amiri
Volume 17, Issue 3 , October 2010, , Pages 489-498
Abstract
Applying methods like seed coating which result in germination improvement, reduction of environmental stresses and increase of range species establishment is utmost important. This experiment was performed to evaluate the effect of different seed coating methods on Sanguisorba minor seed germination ...
Read More
Applying methods like seed coating which result in germination improvement, reduction of environmental stresses and increase of range species establishment is utmost important. This experiment was performed to evaluate the effect of different seed coating methods on Sanguisorba minor seed germination under drought stress and different sowing depths. A factorial experiment in a completely randomized design with three replications was conducted in this research. Treatments included three soil moisture levels (9, 14 and 21 percent of soil dry weight), two sowing depths (surface and three times the diameter of seed), and four seed coatings (control or no seed coating, organic matter, hydro gel and clay seed coatings). Germination percentage was recorded during the experiment. The results of main treatments showed that regardless of the coating type, the effect of all three coating materials on seed germination percentage was significant (p<0.01). The triple interaction effects of soil moisture, sowing depths and coating materials indicated that in surface sowing and all soil moisture levels, there was a significant difference (p<0.01) in seed germination percentage between seed coating and control treatments. No germination was observed in control treatment with 9% soil moisture and surface sowing. Germination percentage for control treatment with 14% soil moisture was 20% recorded as the second rank among the lowest germination levels. In treatment of three times the diameter of seed as sowing depth with 21% soil moisture, there was no significant difference in germination percentage between control and seed coating treatments.