An efficient method in breaking of dormancy from Bunium luristanicum seeds
Mohsen Zafaranieh
1
(Assistance Professor, Department of Agriculture, Technical and Engineering, Velayat University, Iranshahr, Iran)
Masoud Ziae
2
(Department of Plant Production, Faculty of Agriculture, Higher Education Complex of Saravan)
الکلمات المفتاحية: GA3, Germination percentage, Hot Water, H2SO4,
ملخص المقالة :
Abstract. Nowadays, in many rangelands, due to over grazing, and problems that some plants have in germination, the rate of forage production is greatly reduced. So to take advantages of the benefits of such plants, it is necessary to identify and remove barriers of germination and establishment of suitable plants. A study was carried out to investigate the effects of seed dormancy breaking treatments on Bunium luristanicum germination. The experiment was conducted in Vali-e-Asr University of Rafsanjan in 2021. Treatments were arranged in a Completely randomized design (CRD) with five replication. The highest germination percentage was recorded in seeds treated with GA3+hot water (700C) 82 % and GA3+ H2SO4 (50%) 80%, seed scarification with hot water was better than H2SO4, because H2SO4 increased abnormal seedling percentage. The highest seedling weight was recorded in the treatments of GA3 + H2SO4 50% 16.9 mg and GA3 + hot water 70°C 14.9mg. Highest abnormal seedling was shown in H2SO4 75%, GA3 (500 ppm) + H2SO4 75% and KNO3 (1%) + H2SO4 75 % treatments (14%, 14% and 12% respectively (p<0.01). The maximum seedling vigor index was obtained in seeds treated with GA3 (500 ppm) + hot water 700C. Results indicated Bunium luristanicum seeds scarification with hot water 700C (10 min) followed by socking in GA3 (500 ppm) for 12 hour was the most effective treatment for seed dormancy breaking, and improved seedling growth.
Efficient Methods in Breaking SeedDormancy of Bunium luristanicum
Abstract. Nowadays, in many rangelands, due to overgrazing, and climate change, the plant germination, establishment is greatly reduced. So to take advantages of the benefits of such plants, it is necessary to identify and remove barriers of germination and establishment of suitable plants. This study was carried out to investigate the effects of seed dormancy breaking treatments on Bunium luristanicum germination. Data collected and analysed using completely randomized design (CRD) with five replications. The highest germination percentage with average values of 80 and 82% were recorded in seeds treated with GA3+hot water (70°C) and GA3+ H2SO4 (50%), respectively. Seed scarification with hot water was better than sulfuric acid, because acid increased abnormal seedling number. The highest seedling weight with values of 16.9 and 14.9 mg were recorded in the treatments of GA3+ sulfuric acid 50% and GA3 + hot water 70°C, respectively. The highest abnormal seedling was obtained in combination of sulfuric acid 75%, GA3 (500 ppm) + sulfuric acid 75% and KNO3 (1%) + sulfuric acid 75% treatments (14%, 14% and 12% respectively (p<0.01). The maximum seedling vigor index was obtained in seeds treated with GA3 (500 ppm) + hot water 70°C. Results indicated Bunium luristanicum seeds scarification with hot water 70°C (10 min) followed by soaking in GA3 (500 ppm) for 12 hours was the most effective treatment for seed dormancy breaking, and improved seedling growth.
Key words: Gibberellin, Seed Germination, Sulfuric acid, Hot water.
Introduction
Bunium luristanicum is one of the most important species of the family of umbelliferae. The umbelliferae contains about 3000 species of plants dispersed throughout the world, especially in the North hemisphere (Baskin et al., 2014). Seed dormancy is a physiological phenomenon in wild and crop plants, and is more common in wild plants than the crop plants (Farahani et al., 2011). Dormancy can keep some plant species in particular environmental conditions, and one of the most important survival mechanisms in plants, is their ability to delay seed germination until conditions of the location and time are suitable for germination. Thus delay in seed germination is not haphazard, and in many seeds in dormancy, some morphological and physiological changes should occur for germination (Jaganathan, 2020).
Thus, in the absence of physiological dormancy, overcoming physical dormancy may lead to immediate germination of the seeds upon imbibition. Despite the known association between seed coat permeability and embryonic growth potential, the nature of the co-actions between seed coat and embryo growth that determines dormancy is still unclear. A wide range of factors that may potentially disrupt seed coat-imposed dormancy under natural conditions has been identified, with differing implications for seed bank dynamics and seedling emergence patterns (Gama-Arachchige et al., 2012).
However, the importance of low pH for dormancy overcome in intact seeds of Bunium luristanicum has been poorly explored. Chilling plays an important role in providing the stimulus required to overcome dormancy. Chilling has been reported to induce an increase in GA3 concentration (Bretzloff and Pellett, 1979). Asgari et al., (2015) showed that two-month chilling treatments had the greatest impact on seedling fresh weight of Nepeta haussknechtii, N. menthoides, N. cataria, and N. crassifoli. The aimed of this research was to determine treatments that can stimulate and enhance germination of Bunium luristanicum seeds. Thus, the aim of the present study was to analyze the consequence of seed-coat-imposed dormancy on the physiological dormancy and germination of Bunium luristanicum seeds.
Materials and methods
The mature seeds of Bunium luristanicum were collected from Zarand Kerman in central of Iran (Lat: 30.8166° N, 56.5729° E), in 2021. After collection, immature seeds and those damaged by insects were removed.
The seeds were surface sterilized by soaking in 1% sodium hypochlorite (NaOCl) for 5 min and subsequently rinsed thoroughly with sterilized water prior to applying any treatment. A randomized complete design was used with five replications of 25 seeds per each treatment. Seeds were placed on double layered Wath man No.1 filter paper moistened with 5ml of distilled water in sterilized Petri dishes. Treatments to break seed dormancy consisted of the following:
T1: The surface of dry seeds was sterilized with sodium hypochlorite for 15 min seeds were then rinsed with sterile water.
T2: Seeds were soaking in water for 12 hours.
T3: Instead of distilled water potassium nitrate (0.1%) for 12 hours.
T4: Seeds were soaked in a gibberellin 500 ppm solution for 12 hours.
T5: Seeds were dipped in concentrated sulfuric acid (50%) at room temperature (19°C) for 3 min.
T6: Seeds were dipped in concentrated sulfuric acid (75%) at room temperature (19°C) for 3 min.
T7: Seeds were dipped in hot water (70°C) for 10 min.
T8: Seeds were dipped in hot water( 900C )for 10 min.
T9: Seeds were dipped in concentrated sulfuric acid (50%) at room temperature (19°C) for 3 min, then the seeds were soaked in a gibberellin 500 ppm solution for 12 hours.
T10: Seeds were dipped in concentrated sulphuric acid (75%) at room temperature (19°C) for 3 min, then the seeds were soaked in a gibberellin 500 ppm solution for 12 hours.
T11: Seeds were dipped in hot water (70°C) for 10 min, then the seeds were soaked in a gibberellin 500 ppm solution for 12 hours
T12: Seeds were dipped in hot water (90°C) for 10 min then the seeds were soaked in a gibberellin 500 ppm solution for 12 hours.
T13: Seeds were dipped in concentrated sulfuric acid (50%) at room temperature (19°C) for 3 min, then Instead of distilled water, 0.1% potassium nitrate solution was used to saturate the germination substrate at the beginning of the test for 12 hours.
T14: Seeds were dipped in concentrated sulfuric acid (75%) at room temperature (19°C) for 3 min, then Instead of distilled water, 0.1% potassium nitrate solution was used to saturate the germination substrate at the beginning of the test for 12 hours.
T15: Seeds were dipped in hot water (70°C) for 10 min, then Instead of distilled water, 0.1% potassium nitrate solution was used to saturate the germination substrate at the beginning of the test for 12 hours.
T16: Seeds were dipped in hot water (90°C) for 10 min, then Instead of distilled water, 0.1% potassium nitrate solution was used to saturate the germination substrate at the beginning of the test for 12 hours.
After each treatment, seeds were transferred into the germinator with continuous darkness, a constant temperature of 20°C, and relative humidity between 70% and 75%. Germinated seeds were counted and removed every 24 h for 45 days (Nadjafi et al., 2006). A seed was considered germinated when the tip of the radicle had grown free of the seed coat.
Germination percentage, germination rate, and Seed vigor index were measured based on the following relationship.
Where:
n = the number of germinated seeds,
N =the total number of seeds and
ni = the number of germinated seeds in day ti.
Sl = shoot length(cm).
Rl = root length (cm).
After the Arcsin transformation, the percentage of germination was subjected to an analysis of variance. The data were analyzed using a randomized complete design with five replications and the LSD for comparison at P<0.05 was calculated using LSD t-test.
Results and Discussion
In our experiment, the analysis of variance showed highly significant differences among the genotypes for all 16 characters studied (Table 1).
Germination percentage
There was a significant difference between the germination percentage in different treatments (Table 1). Results showed a germination percentage of 13% for the control condition, germination percentage under application of GA3+Hot water 700C, GA3+H2SO4 50% and GA3+Hot water (900C) were 82%, 80%, and 79%, respectively. These results show that B. luristanicum seed dormancy was influenced by physiological and physical factors. since the application of GA3, H2SO4 50%, H2SO4 75%, hot water 70°C, and hot water 90°C increased germination percentages of 38%, 30%, 63%, 60%, and 58 %, respectively, it was concluded that the seed dormancy B. luristanicum may be more affected by physical factors, because the scratching treatments were more effective than the the application of GA3 or KNO3 alone (Table 1). After combined treatments of GA3 and scratching the seed coat, the highest germination percentage was due to application KNO3 + H2SO4 70% (80%), KNO3+hot water 700C (67%), and KNO3+hot water 900C (79%). The effect of GA3 on seed germination under room temperature condition showed that seed dormancy in B. Luristanicum was from an intermediate physiological type of non-deep, complex morph physiological dormancy (Zhou and Bao, 2011).
Abnormal seedling
Examination of the percentage of abnormal seedlings showed that seed dormancy treatments used H2SO4 75% and the combination of this treatment with GA3, and KNO3 had the highest number of abnormal seedlings (14%, 14%, and 12%, respectively). Application H2SO4 50% as well as hot water 90°C alone or in combination with treatments or GA3 and KNO3 produced a lower abnormal seedling production. Also, the application of higher concentrations of H2SO4 and higher concentrations of H2SO4, such as 100%, much increased the number of abnormal seedlings (Bhardwaj et al. 2010). The best combination to break the dormancy of Arctium lappa seeds is the combined use of KNO3, and scratching the seeds with hot water (Nabaee et al., 2013).
Germination rate
The results showed that the highest seed germination rate with average values of 4.3, 4.2 and 4.1 seeds per days were obtained under application GA3 + hot water 900C, GA3 (500 ppm) +Hot water 700C and GA3(500 ppm)+H2SO4 75% , respectively (Table 1).
Control treatment and seed soaking in water treatment had the lowest germination rate (0.3 and 0.4 seeds per day). Hot water 700C, hot water 900C, H2SO4 50%, H2SO4 75% and GA3 also increased the germination rate to 2.3, 2.9, 1.7, 2.4, and 1.6 seeds per day, respectively. These results show that scratching the seed coat with H2SO4 and application GA3 increases seed germination rate (Table 1). The present study shows a synergistic effect on promoting germination of Cordia sinensis seeds when the seeds are treated with an aqueous solution of gibberellins supplemented with potassium nitrate solution. Similar synergistic results of KNO3 (1%) and GA3 (500 ppm) seed treatments were reported by Dewir et al. (2011) in Sabal palmetto. Whereas, soaking cracked seeds of Elaeocarpus prunifolius in the solution of GA3 and KNO3 accelerate the germination rate (Iralu and Upadhaya, 2018).
Root and Shoot Length
The maximum root length of 55 and 49mm were observed in GA3+ hot water at 70°C and GA3+ H2SO4 at 50% (, respectively. The application of hot water at 70 and 90°C alone had a much longer root length than the application of H2SO4 50% and 75%, GA3, or KNO3 (Table 1). The lowest root length was observed in the control treatment and seed soaking in water (18 and 16 mm, respectively). The lowest shoot length was observed in the control treatment, soaking the seeds in water and KNO3 (11, 14, and 13 mm, respectively). Treated seeds with GA3 + H2SO4 50%, GA3 + hot water 70°C, and KNO3 + hot water 70°C increased the shoot length to 41, 38, and 38 mm, respectively (Table 1).
Seedling Dry Weight
In this study, the application of GA3 and KNO3 increased the dry weight seedlings to 8.5 and 10.6 mg, respectively, which indicates the more significant effect of GA3 on Bunium seedling growth. Also, the shoot and root length in Bunium was significantly affected by the use of GA3 more than the application of KNO3, which confirms this result (Table 1) Application of physical treatments such as sulfuric acid and hot water in essential for Bunium break dormancy and stimulation of seedling growth, but 90°C hot water or high concentrated sulfuric acid can damage seedling growth. The effect of physical and physiological break dormancy treatments on seeds showed that the application of sulfuric acid had a significant role in seed break dormancy.
Vigor index
The highest seed vigor index was observed in seeds treated with GA3 + hot water 70°C, however, the lowest seed vigor index was recorded in control treatments, seed soaking in water and control. After GA3 + hot water 70°C, seed treatment with GA3 + H2SO4 50% and 75%, GA3 + hot water 90°C, KNO3 + hot water 70°C increased seed vigor index (Table 1). Seed vigor index indicates seed potential for germination, seedling growth, and tolerance to adverse environmental conditions during germination. Seed vigor index indicates seed potential for germination, seedling growth, and tolerance to adverse environmental conditions during germination and it is an essential indicator during germination, influenced by various factors such as genetics, environmental conditions in the seed development period and seed germination improvement treatments (Hu et al. 2018). Therefore, it can be expected that seed vigor index will increase via seed break dormancy treatments which will lead to increased germination rate, seedling growth and germination percentage. It can be concluded that for Bunium seeds, GA3 with hot water stimulates seed germination and has a more significant effect than the other treatments applied in this study. Tavili et al (2014) showed, sulfuric acid had the higher effect in breaking dormancy, but its application in a vast scale is not easy, therefore the hot water could be considered as the substitution treatment.
Table 1. Effect of seed dormancy breaking treatment on Bunium luristanicum germination and seedling growth
Dormancy breaking treatments | Germination percentage | Abnormal Seedling percentage | Germination rate (no./day) | Root length (mm) | Shoot Length (mm) | Seedling dry weight(mg) | Vigor index |
Control | 13 g | 1 e | 0.3 e | 18 f | 11 e | 6.6 f | 297 f |
Soaking in water (12 h) | 15 g | 1 e | 0.4 e | 16 f | 14 ed | 6.4 f | 272 f |
Soaking in KNO31% solution (12h) | 22 f | 1 e | 2.0 c | 23 e | 13 ed | 8.5 e | 447 f |
Socking in GA3 (500 ppm. 12h) | 38 d | 1 e | 1.6 d | 23 e | 17 d | 10.6 d | 1809 e |
H2SO4 50% (3min) | 30 e | 7 c | 1.7d | 23e | 19d | 11.9c | 1169 e |
H2SO4 75% (3min) | 63 c | 14 a | 2.4 c | 23 e | 27 c | 8.3 e | 1782 e |
Hot water 700C(10 min) | 60 c | 1 e | 2.3c | 32d | 25c | 12.3b | 2894 d |
Hot water 900C(10 min) | 58 c | 6 c | 2.9 bc | 30 d | 33 b | 13.2 b | 2798 d |
GA3 (500ppm)+H2SO4 (50%) | 80 a | 9 b | 3.4 b | 49ab | 41a | 16.9 a | 2844 d |
GA3 (500 ppm)+H2SO4 (75%) | 76 ab | 14 a | 4.1a | 43 b | 34 b | 13.9 b | 5789 b |
GA3 (500ppm)+Hot water (700C) | 82 a | 5 d | 4.2 a | 55a | 38a | 14.9 a | 8012 a |
GA3 (500ppm)+Hot water (900C) | 79 ab | 9 b | 4.3a | 42 b | 32 b | 9.9 e | 5326 b |
KNO3 (1%) + H2SO4 (50%) | 67 bc | 12 a | 2.8 bc | 46b | 40a | 14.5b | 4265 c |
KNO3+H2SO4 (75%) | 74 b | 1 e | 3.2 b | 38 c | 32 b | 13.1 c | 4258 c |
KNO3+Hot water (700C) | 76 b | 1 e | 3.2 b | 42b | 38 a | 14.3 b | 4402 c |
KNO3+Hot water (900C) | 69 b | 8 b | 3.2 b | 40 b | 36 a | 12.1 b | 4241 c |
Means of square (MS) | 1243.14** | 11.9** | 8.2** | 3.5** | 0.523** | 7.3** | 218** |
** Significant at the 0.01 probability level, Means of colomn with the same letter are not significantly different.
Conclusions
Considering the results of the present research, it can be seen that seed immersion in GA3 + hot water70°C is the best treatment for both improving the germination factor and producing healthy, high quality seedlings. Although, treatments like the use of GA3 + hot water 90°C, GA3 + H2SO4 75% also had the highest germination percentage, they led to the damage to the seedling structure, decrease in seedling weight, increase in the percentage abnormal seedlings and finally decrease the seed vigor index. Due to the ease of using the hot water treatment of GA3, it is recommended to recruit the treatment of GA3 500 ppm + scratching the seed coat with hot water 700C for 10 minutes to improve the germination of Bunium seeds.
References
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The highest seedling weight with values of 16.9 mg and 14.9mg were recorded in the treatments of GA3+ sulfuric acid 50% and GA3 + hot water 70°C, respectively. The highest abnormal seedling was obtained in combination of sulfuric acid 75%, GA3 (500 ppm) + sulfuric acid 75% and KNO3 (1%) + sulfuric acid 75% treatments (14%, 14% and 12% respectively (p<0.01). The maximum seedling vigor index was obtained in seeds treated with GA3 (500 ppm) + hot water 70°C. Results indicated Bunium luristanicum seeds scarification with hot water 70°C (10 min) followed by soaking in GA3 (500 ppm) for 12 hours was the most effective treatment for seed dormancy breaking, and improved seedling growth.
روشهای موثردر شکستن خواب از بذر Bunium luristanicum
چکیده. با توجه به وجود فشار چرای دام و مشکلات ناشی از جوانهزنی برخی گیاهان مهم مرتعی، تولید این گیاهان در عرصهای مرتعی کاهش یافته است. به منظور تقویت حضور این دسته از گیاهان در مراتع ، شناسایی موانع جوانهزنی و رفع آنها جهت استقرار موفقیت آمیز حایز اهمیت است. مطالعهای به منظور بررسی اثرات تیمارهای شکست خواب بذر بر جوانه زنی Bunium luristanicum انجام شد. تیمارها در قالب طرح کاملاً تصادفی با پنج تکرار انجام شد. بیشترین درصد جوانهزنی با 82 و 80 درصد به ترتیب در بذرهای تیمار شده با آب گرم (70 درجه سانتیگراد)+ جیبرلین (GA3)، و اسید سولفوریک (50 درصد)+ جیبرلین بود، خراش دهی بذر با آب گرم بهتر از اسید سولفوریک بود، زیرا اسید سولفوریک درصد گیاهچه غیر طبیعی را افزایش داد. بیشترین وزن گیاهچه با 9/16 و 9/14 میلی گرم به ترتیب در تیمارهای اسید سولفوریک 50%+ جیبرلین و آب گرم 70 درجه سانتی گراد + جیبرلین ثبت شد. بیشترین تعداد گیاهچه غیر طبیعی در تیمارهای اسید سولفوریک (75%)، جیبرلینppm500 +اسیدسولفوریک (75%) و اسید سولفوریک (75%)+ KNO3 (1%) به ترتیب با 14%، 14% و 12% بدست آمد (p<0.01). بیشترین شاخص بنیه گیاهچه در بذور تیمار شده با جیبرلینppm 500 + آب گرم 70درجه سانتیگراد بدست آمد. نتایج نشان داد خراش دادن بذر B.luristanicum با آب گرم 70 درجه سانتیگراد (10 دقیقه) و سپس قرار دادن در جیبرلین ppm500 به مدت 12 ساعت موثرترین تیمار برای شکستن خواب بذور و بهبود رشد گیاهچه این گیاه باشد.
کلمات کلیدی: اسیدجیبرلیک، درصد جوانهزنی، اسیدسولفوریک، آب داغ
