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Volume 1, Issue 2 (1-2015)
Seed priming is one of the most important techniques used to improve seed germination under biotic and abiotic stresses. For this purpose, germination and seedling growth characteristics of primed seeds of Tall wheatgrass (Agropyron elongatum (Host.) P. Beauv) were evaluated under drought and low-temperature condition. A factorial experiment was conducted on the basis of randomized completely block design with three factors with four replications. The experimental factors were priming with two levels including urea primed (using urea -4 bar at 10 °C for 36 h) and non-primed seeds germination temperatures, including 3, 6, 9, 12, 15, 20 and 25 °C and osmotic potential including zero (distilled water), -3, -6, -9, and -12 bars (applied by polyethylene glycol 6000). Increasing trend has been observed for all germination indices, except mean germination time, with increasing temperature from 3 to 25 °C and seeds revealed the greatest sensitivity to temperatures below 9 °C. However, this trend was reversed with increasing drought stress, the seeds sensitivity to drought stress started from the potential of -6 bar and reached the maximum in -12 bar. However, primed seeds compared to non-primed seeds have demonstrated better germination under both drought and low-temperature stresses. The results of this study showed that the highest seedling vigor index and germination rates achieved in the temperature range of 20-25 °C and water potential of zero to -3 bar.
Volume 3, Issue 2 (2-2017)
In order to study the effect of zinc and magnesium on agronomic and seed germination traits of wheat (Sivand cultivar), the current study was carried out at Mahidasht Agricultural Research Station in Kermanshah over the years 2012 and 2013. The experiment was conducted as factorial based on completely randomized block design with three replications. The treatments consisted of four levels of zinc sulfate (zero, 20, 40 and 60 kg per hectare) and four levels of magnesium (zero, 70, 140 and 210 kg per hectare in the form of magnesium sulfate). The measured parameters included thousand seed weight, hectoliter weight, protein, zinc and magnesium seeds, germination test, growth rate, seed vigor, plant characteristics and grain yield. The results showed the effects of zinc and magnesium factors were significant for most traits at 1 and 5%. The effect of zinc sulfate showed that 60 kg zinc sulfate had the best effect on the traits under investigation. The effect of this treatment on two important traits (i.e., yield and grain protein percent) with 7.10 tons per hectare and 12.05% was higher (about 115 and 103%, respectively), as compared with the control treatment. Effect of magnesium sulfate levels on the traits showed that the treatment of 210 kg per hectare of magnesium sulfate was the superior treatment. The effects of the above-mentioned treatment on yield (7.84 tons per hectare) and grain protein (11.89 percent) were higher than the control treatment, which was 124 and 101.5%, respectively. Given the number of field nutrients and the wheat needs for these elements, the treatments of 20 kg per ha of zinc sulfate and 140 kg per ha of magnesium sulfate were better than other treatments and economically speaking, are very cost-effective and are thus recommended.
Volume 4, Issue 2 (3-2018)
In order to study the effects of different levels of salinity on germination components of wheat cultivars, a factorial experiment was conducted based on a completely randomized design with three replications. Experimental factors were wheat cultivars at eight levels (Saysons, Gaspard, Finkan, MV-17, Chamran, Sardari, Atila-4 and Azar-2) and six levels of salinity (0, 25, 50, 100, 150 and 200 mM NaCl). The results indicated that salinity had significant effects on all of the traits studied (i.e., radicle length and dry weight, plumule length and dry weight, remaining seed weight after germination, seedling weight, the longest radicle and plumule, number of radicle per seed, ratio of radicle weight to plumule weight and rate, and uniformity and percentage of germination). All of these traits declined with an increase in the salinity (except the ratio of radicle weight to plumule weight, remaining seed weight after germination and seedling weight). The highest ratio of radicle weight to plumule weight, remaining seed weight after germination and seedling weight were recorded in the salinity of 200 mM NaCl. The cultivars showed significant effects on all of the traits studied (except remaining seed weight after germination and seedling weight). Chamran cultivar showed the highest number of radicle per seed, the ratio of radicle weight to plumule weight, rate and percentage of germination. The highest radicle length and the longest radicle were obtained from the Sardari cultivar while in Azar-2 cultivar it was vice versa in plumule. Atila-4 cultivar showed the highest radicle and plumule weight. It seems that compared with other cultivars, out of the cultivars studied, Chamran, Azar-2, Sardari and Atila-4 were more resistant to salinity stress.
Highlights:
- Introduction of wheat cultivars with more tolerance to salinity conditions at germination stage.
- Study of eight different wheat cultivars in terms of germination indices under salinity stress conditions.
Volume 7, Issue 2 (3-2021)
Introduction: Water deficit stress is one of the important factors affecting seed germination. This stress decrease germination rate and affects germination percentage under high levels as well. Seed priming improves germination by changing metabolic activities before radicle emergence. This investigation was conducted to evaluate the effect of seed priming by salicylic acid on the emergence index and grain weight of spring wheat under water deficit stress.
Material and Method: These experiments were conducted as factorial based on the completely randomized design with three replicates in the greenhouse of the Faculty of the Agriculture Sciences University of Mohaghegh Ardabili. Experiment treatments included different salicylic acid concentrations (0, 1, 2 mM) and water deficit stresses (25%, 45%, 65% and 85% Field capacity).
Result: According to results, emergence index (emergence percentage and emergence rate, uniformity emergence, and times to 10, 50, and 90% emergence) was influenced at 1% by water deficit stress. The effect of salicylic acid was significant on the emergence index. The interactions of water deficit stress and salicylic acid were effective at 1% on emergence uniformity and time to 90% emergence. Changes in plant height and heading rate were lower under water deficit stress. Also, both slope (b) and maximum content (a) decreased by water stress (22% and 7%). Priming by salicylic acid at 2 mM had the highest effect on both traits and resulted in a decrease in their slopes (17% and 13%) and an increase in their maximum content (34 and 10%). Plant dry weight was influenced by the interactions of water deficit stress and salicylic acid at 5% level. The plant's final height and grain weight was influenced by water deficit stress and salicylic acid. The highest grain weight was obtained at 80% and 60% field capacity with means of 0.79 and 0.75 g, which had no significant differences with eachother. The heights grain weight (0.72 g) was obtained by application of 2 mM salicylic acid which led to an increase of 250% compared to control.
Conclusions: Overall, we showed that water deficit stress resulted in decreased emergence rate and emergence percentage of wheat and finally declined plant growth and grain weight. Application of salicylic acid in seed priming resulted in improvement in the emergence index, growth, and grain weight of wheat. Also, the highest grain weight was observed at 2 mM concentration and it can be considered as the enhancing treatment.
Highlights:
1- Response of plant growth stage to stress was quantified using nonlinear regression
2- Relationship between emergence and grain weight was investigated under stress and priming by salicylic acid.
Volume 7, Issue 2 (3-2021)
Introduction: Germination is one of the most important stages of plant growth that determines the durability, establishment and final yield of crops and in regions that due to drought conditions the growth of plant encounters with problem, improving germination traits count as one of the important breeding strategies. The present study was designed to determine the effect of different levels of osmotic stress on germination and seedling traits of some bread wheat cultivars cultivated in cold regions of Iran.
Materials and Methods: In order to investigate the effect of different levels of osmotic stress on germination characteristics of bread wheat cultivars cultivated in cold regions of Iran, a factorial experiment was conducted based on a completely randomized design with 3 replications in which, the first factor consisted of 20 bread wheat cultivars (including rain fed cultivars as well as end-of-season water stress tolerant varieties) and the second factor consisted of 3 levels of osmotic stress (non-stress, -3 and -6 bar stress). Seedling traits such as coleoptile length, shoot length, shoot weight, root length, root weight, root / shoot ratio, root growth angle, germination speed and the germination stress index (GSI) were evaluated. For the experiment concerning the yield comparison, 20 cultivars mentioned above were compared under non-stress and terminal drought stress conditions.
Results: The results showed that the ratio of root/shoot length and weight and shoot weight had the highest sensitivity and the lowest number of roots to osmotic stress. Increasing root length as root weight decreased with increasing stress showed that roots became longer and thinner due to stress. Among the genotypes, Saein, Zare, Pishgam, Sadra, Baran and Mihan had desirable traits and CrossMV17, Homa, Orum and Cross Azar2 had no desirable germination traits. In non-stress conditions, 11 genotypes had high coleoptile length including Hashtrood, Azar 2, Saein, CD62-6, CD91-12, Mihan, Baran, Heydari, Homa, Cross Azar 2 and Zare genotypes. At 3 bar stress, 11 genotypes had the highest coleoptile length, with the highest values being assigned to Hashtrood, Heidari and Saein. At 6 bar stress, CD91-12 and CD62-6 lines, Hashtrood, Homa, Pishgam, and Zare had the highest coleoptile length. At 3 bar stress cross Azar 2, Saein, CD62-6, Gascogen and HD2985 demonstrated the highest germination rate. Furthermore, Cross Azar2, HD2985, Gascogen, CD62-6 and Saein led to the best results, respectively. However, in both 3 and 6 bar stress conditions Saein, Cross Azar2, CD62-6 and HD2985 were superior for germination stress index (GSI). For grain yield under normal conditions, Gascogen, Heidari, Pishgam, Orum and Zarrineh had the highest yield and Baran, HD2985, C-88-4, C-9011 and Cross Azar2 were placed next. Under stress conditions Baran, Gascogen, HD2985, Cross Azar2, Heidari and Zarrineh consisted the highest performance. According to STI index Gascogen, Heidari, HD2985 and Zarrineh were the most tolerant genotypes to drought stress. Cluster analysis grouped the studied genotypes into 2 clusters, the first cluster comprising 13 genotypes Heidari, Mihan, HD2985, Baran, Pishgam, Hashtrood, Cross Azar 2, CD62-6, Gascogen, Azar 2, Saein, Sadra and Zare. The second cluster consisted of 7 genotypes C-88-4, Zarineh, C-90-11, Orum, CD91-12, CrossMV17 and Homa. Genotypes of cluster 1 were superior in terms of germination traits such as shoot length, coleoptile length, root length and root weight and reduced root/shoot ratio.
Conclusion: Significant differences in all studied traits among genotypes indicated sufficient genetic variation for selection in germination traits. Results showed that Saein, Zare, Pishgam, Sadra, Baran and Mihan cultivars had desirable germination traits and were superior to other genotypes.
Highlights:
1- The tested genotypes are either newly named or advanced lines and have not been studied for germination traits.
2-The growth angle trait of seed roots through filter paper has received little attention in studies.
Volume 11, Issue 1 (9-2024)
Introduction: The germination stage in plants, including wheat, is an extremely susceptible stage to biotic and abiotic stresses. Plant establishment the in the early stages of growth, especially in the germination stage, is always notably important. Salinity stress is one of the abiotic stresses that cause much damage annually, especially in arid and semi-arid regions. Therefore, identification and use of cultivars tolerant to salinity stress is one of the effective ways to reduce the negative effects of salinity stress.
Materials and Methods: In the present study, response of 64 spring wheat cultivars during the germination stage at two levels of salinity stress (zero as a control and 12 dS/m of sodium chloride) was investigated in the form of a simple lattice design with two replications at the Genetics Laboratory of the Faculty of Agriculture, Urmia University. During seven days, germination percentage, germination index, germination rate, germination energy, seedling vigor, mean germination time, and mean germination rate, and after the seventh day, seedling length, shoot length, root length, ratio of shoot length to root length, seedling fresh weight, and seedling dry weight were measured.
Results: Among the studied cultivars, a statistically significant difference was observed at the probability level of 1% in terms of all traits including radicle length, shoot length, seedling length, fresh weight, dry weight, radicle to shoot length ratio, germination index, germination rate, germination energy, germination percentage, seedling vigor, mean germination time, and mean germination rate. Based on the results of factor analysis, under both normal conditions and salinity stress, the studied traits were grouped into four main factors, and these four factors explained 92.74% of the changes under normal and 93.85% under salinity stress conditions. Using cluster analysis, cultivars were grouped into three and two clusters under normal and salinity stress conditions, respectively.
Conclusions: Based on the results of bi-plot obtained from factor and cluster analyses, the cultivars Moghan 2, Bistun, Akbari, Moghan 3, Dastjardi, Marvdasht, Gahar, and Mahdavi are the preferred cultivars and the cultivars Darya, Bam, Tajan, Sistan, Frontana, Kavir, and Afogh were introduced as undesirable cultivars in terms of the traits measured in this experiment, which can be used in breeding projects.
Keywords: Bread wheat, Germination, Multivariate analysis, Salinity stress
Highlights:
- A great diversity was observed among Iranian spring wheat cultivars in terms of salt tolerance during germination.
- Mahdavi, Dastjardi, Bistun, Akbari, Moghan 2, Moghan 3, Gahar, and Marvdasht were identified as salt-tolerant cultivars during germination.
Volume 11, Issue 1 (9-2024)
Introduction: Drought stress in dryland wheat cultivation, where the plant solely relies on rainwater, can have a detrimental effect on plant growth. Given the lengthy duration of breeding projects, identifying stress-tolerant breeding lines at the germination stage can significantly reduce the time and cost of dryland wheat breeding programs for developing drought-resistant varieties. Identifying the stress tolerance of unreleased lines through laboratory simulation of drought stress is among novel methods to aid in selecting drought-tolerant varieties in the final stages. Moreover, the germination stage is crucial for plant establishment. This stage is critical for plant growth and development and can significantly impact bread wheat yield in case tolerant lines are available.
Materials and Methods: This experiment was conducted to investigate the germination characteristics of 11 advanced dryland bread wheat lines at four osmotic potential levels (-2, -4, -6, and -8 bars) induced by polyethylene glycol 6000 along with a control (for a total of five levels), under laboratory (controlled) conditions at Persian Gulf University. The investigation was performed as a factorial experiment in a completely randomized design (CRD) with three replications. Traits in this experiment including germination percentage, germination rate, growth rates of radicles and plumules, dry weight and length of radicle and plumule, seed vigor indices I and II, seedling length, and allometric coefficient were measured.
Results: The mean of all traits decreased with increasing stress levels. Results of ANOVA showed a significant interaction at the 1% level between the lines and drought stress treatments. Therefore, physical slicing analysis was conducted at each stress level to compare the lines. The response of the lines to different traits was of an ordinal interaction type. As drought stress levels increased, germination percentage and rate, radicle and plumule growth rates, and seedling length decreased. Overall, lines 3 and 4 exhibited the highest germination percentage (58.86) and rate (3.60 seeds per day), as well as radicle (0.85 cm per day) and plumule rates (0.70 cm per day), and radicle (8.83 cm) and seedling (7.12 cm) length.
Conclusions: The response of the lines to different osmotic stress levels varied in terms of various traits. Based on the traits evaluated, lines 3 and 4 exhibited superior drought stress tolerance. These lines can be utilized in future breeding programs.
Highlights:
- Evaluating and screening wheat breeding lines for drought tolerance was performed by simulating stress conditions in the laboratory and comparing morphological traits in early plant growth stages.
- The response of the lines to similar levels of drought stress was heterogeneous, and physical slicing analysis based on each stress level revealed an ordinal interaction between stress and line levels.
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