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Volume 4, Issue 2 (3-2018)
Salt and drought are two major environmental stresses that affect growth and development of plants. In order to study the effects of sodium chloride and polyethylene glycol (6000) on germination characteristics and early seedling growth of redroot pigweed (Amaranthus retroflexus), two completely randomized designs with 4 replications were conducted at Weed Research Laboratory of Bu-Ali Sina University, Hamedan in 2015. The treatments were salt and drought stress as osmotic potential at six levels (zero (control), -2, -4, -6, -8 and -10 bar). The results showed that when stress increased, germination percentage, germination speed, radicle and plumule length, seedling length and seedling vigor index decreased significantly (p≤ 0.05). With an increase in the intensity of salt and drought stress from zero to -10 bars, redroot pigweed seed germination reduced about 96 and 100 percent, respectively, compared with the control. The highest seedling length in both stresses was observed in the control (7.71 cm) and by increasing stress intensity to -10 bars in both salinity and drought stresses, seedling length was reduced to 1.52 cm and 0 cm, respectively. Fitting of the three-parameter logistic model provided a successful estimation of the relationship between salt and drought stress levels and germination percentage of redroot pigweed as well as germination speed. This model showed that salinity and drought stress at -3.58 and -3.75 bars caused a 50% reduction in maximum germination percentage of redroot pigweed. In addition, 50% decrease in germination speed caused by salinity and drought stress was observed in -2.58 and -2.88 bars, respectively.
Highlights:
- The germination characteristics of redroot pigweed were studied under salt and drought stresses.
- Drought stress reduced germination percentage of redroot pigweed.
Volume 6, Issue 1 (9-2019)
Extended Abstract
Introduction: Strangle wort (Cynanchum acutum) is a perennial weed that could be propagated by seeds and vegetative organs. This brings about harvesting problems for some crops such as cotton, sugar beet, wheat and maize. In recent years, this weed has caused huge losses in sugar cane fields. The role of environmental conditions in weed management is highly important. Given this, the present study seeks to investigate the effects of environmental conditions (salinity and drought stress) on germination characteristics of strangle wort weed.
Materials and Methods: In order to investe the effect of different salinity and drought levels on strangle wort (Cynanchum acutum), two seperate experiments were conducted at Hakim Farabi Khuzestan Sugar Cane Research Institute in 2014-2015. The experimental design was completely randomized, with four replications. The treatments were different salinity levels at 8 levels (0, 2.5, 4.5, 6.5, 8.5, 12.5, 16.5 and 20.5ds/m) and the second experiment involved different drought stresses (osmotic potential) at 7 levels (0, -1, -3, -6, -9, -12 and -15 bar).
Results: The results of salinity stress experiment showed that with increases in salinity levels from 0 to 20.5 ds/m, germination, radicle length, plumule length and seedling weight decreased by 61, 80, 91 and 99%, respectively. The results of drought stress experiment showed that with increases in salinity levels from 0 to -15 bar, all studied traits, i.e., germination, radicle length, plumule length and seedling weight all decreased by 100%.
The analysis of variance results showed that in all the traits, there were significant differences between salinity and drought stress in 1% probability level. In this research, in the salinity experiment, in most of traits, especially radicle length quickly decreased after 8.5 ds/m salinity to higher levels and in drought stress experiment, after -3 bar to higher levels.
Conclusion: On the whole, it seems that sufficient information about this weed is vital for the adoption of the best control method, and gaining insights into how strangle wort responds to environmental stress, especially salinity stress, could help us to come up with new control approaches for this invasive weed. This can present a proper ecological approach that could be adopted in sustainable agriculture programs, which is environmentally sound as it decreases the use of chemical inputs. In addition, in order to lower the tolerance of this weed to salinity and especially drought stress, it is suggested that it be used for weed management programs. According to the results of this study, soil salinity higher than 8.5 ds/m and drought tension above than -3 bar can cause sizeable reduction in most traits (growth parameters) especially in root length. In most of the traits scrutinized, the tolerance of the weed to salinity and drought stress was 12.5 ds/m and -6 bar, respectively.
Highlights:
- Evaluation of germination characteristics of strangles wort under salinity and drought stress conditions.
- Determination of tolerance threshold of strangles wort germination seed to salinity and drought stress.
Volume 9, Issue 1 (9-2022)
Introduction: Drought stress, as abiotic and multidimensional stress, has severe effects on plant growth. One of the new approaches in the management of drought stress is the use of nanoparticles. Nanoparticles infilterate the seeds and increase nutrient and water uptake and ultimately, improve germination. The present research was conducted to evaluate the effects of titanium dioxide nanoparticles on chickpea plant germination factors to modify the negative effects of drought stress.
Materials and Methods: A factorial experiment was conducted in a completely randomized design with four replications on chickpea seeds of Arman cultivar in the Plant Sciences Research Institute of the Ferdowsi University of Mashhad in 2019. Seeds were primed with concentrations of 0, 5, 10, 15, and 20 mg L-1 titanium dioxide for 24 hours. The seeds were cultured in sterilized Petri dishes. Drought stress was applied using polyethylene glycol 6000 with 0, -2, -4 and -8 bar osmotic potentials.
Results: The analysis of variance results showed that the interaction effect of drought stress and titanium dioxide nanoparticles was significant on germination rate, the number of normal seedlings, seed vigor index, germination index, length of seedling, radicle length, and radicle dry weight. All germination traits were inhibited as a result of drought stress. On the other hand, the presence of titanium dioxide nanoparticles partially decreased this inhibition in some traits. Germination percentage, germination rate, normal seedling percentage, seed vigor index, germination index, epicotyl length, radicle length and radicle dry weight decreased as a result of stress.
Conclusion: At all drought stress levels, the concentration of titanium dioxide nanoparticles up to 20 mg L-1 significantly improved traits such as germination percentage, seed vigor index, epicotyl length, and epicotyl dry weight. It seems that nanoparticles can stimulate cell activity and increase the transformation of reserves to translocatable material and consequently, improve germination characteristics. Thus, the application of titanium dioxide nanoparticles up to a concentration of 20 mg L-1 can partially reduce the negative effects of drought stress on the germination characteristics of chickpeas.
Highlights:
1- Germination percentage and seed vigor index of chickpea increased with the application of titanium dioxide nanoparticles up to 20 mg l-1 at all drought stress levels.
2- The radicle length and dry weight of chickpea increased by titanium dioxide nanoparticles.
3- The negative effects of drought stress on chickpea seed germination decreased by titanium dioxide nanoparticles.
Volume 9, Issue 2 (3-2023)
Extended Abstract
Introduction: Lentil is a dicot, annual, and cross-pollinating plant that is found mainly in Fars, Khuzestan and East Azerbaijan provinces. The seeds of the plant are used in the treatment of cholesterol and blood sugar. Abiotic stresses such as salinity are important factors in reducing plant growth and yield. Although salinity can remarkably affect plant growth, its intensity depends on duration, type, plant species and growth stage. The greatest effect of salinity during the germination process is on germination rate and percentage and radicle and plumule length, as the increased concentration of ions in Therefore, studying of plant germination under salt stress and application of compounds such as salicylic acid to improve plant tolerance to salinity in saline areas can serve as a guideline for the cultivation of plants under such conditions. Therefore, this research aimed to study the effect of salicylic acid on the germination and growth parameters of Securigera securidaca L. under salinity conditions.
Materials and Methods: The experiment was conducted as a factorial in a completely randomized design with three replications under the germinator conditions in the laboratory of Fars Agricultural and Natural Resources Research and Education Center. Experimental treatments consisted of 5 levels of salinity stress (0, -0.3, -0.6, -0.9 and -1.2 MPa) and 3 levels of salicylic acid (0, 1 and 2 mM). The seeds were soaked in the treatments for 24h. At the end of the experiment (8 days), germination percentage and rate, seed vigor index, and fresh and dry weight of radicle and plumule were measured and calculated.
Results: The results showed that all plant responses were affected by different osmotic potentials at p<0.01 compared with the control. The highest germination percentage was 91.11 under stress-free conditions and the application of salicylic acid at 1 mM. During the comparison of means for salicylic acid, the highest mean plumule length (10.88 mm) was related to 1 mM salicylic acid solution and the lowest (6.35 mm) was for control treatment, which showed an increase of 71.34%. Also, soaking seeds with salicylic acid caused an 84.98% increase in root fresh weight. An increase in salinity led to 96.30 and 94.62% decrease in radicle and plumule dry weights, respectively.
Conclusions: The study showed that soaking seeds with salicylic acid improved germination under salt stress conditions. Therefore, seed placement in salicylic acid solution (1 Mm) prior to cultivation can be used to improve the germination of Securigera securidaca L. under salinity conditions.
Highlights:
1- The most suitable concentration of salicylic acid for seeds soaking to increase plant tolerance to salinity stress is 1 mM.
2- Soaking of Securigera securidaca L. seeds in salicylic acid increases germination, seed vigor index and radicle and plumule length and weight under saline and non-saline conditions.
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Seed Science and Technology, Seed Physiology, Seed Ecology, Modeling, Seed Health, Germination Characteristics, Seed Dormancy, Seed Ageing, Seed Storage, Seed PrimingVote
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