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| Methods of Breaking Seed Dormancy |
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| Natural Methods |
| i) Microorganisms present in the soil weaken and decompose the hard seed coat |
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| ii) The digestive juices present in the alimentary canal of the fruit eating birds makes the seed coat soft |
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| iii) Mechanical abrasions weaken the tough and impermeable seed coat |
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| iv) Washing away of inhibitors by rain or irrigated water |
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| v) Inactivation of growth inhibitors by heat and cold |
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| vi) Leaching of solutes in halophytes where dormancy is due to high concentration of salts |
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| vii) Synthesis of growth hormones |
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| viii) Maturation of embryo |
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| Scarification |
| It is the weakening of seed coats by mechanical abrasions or chemical treatments. |
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| Mechanically, the abrasions are caused by machine threshing, vigorous shaking. |
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| Chemically, the seeds are treated with chemicals like potassium nitrate, thiourea, ethylene, chlorohydrine to make the seed coats soft and weak. |
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| Low Temperature (Chilling) |
| In many woody and in certain herbaceous species the dormancy can be broken by chilling treatments, just above freezing (0 - 5o C). |
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| Alternating Temperatures |
| Seeds are exposed to alternating high and low temperatures to reduce the concentration of the inhibitory substances. |
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| Running Water Treatment |
| Running water washes off the inhibitors from the seeds and breaks dormancy. |
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| Light |
| In some plants, dormancy can be broken by exposing them to light. |
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| Hormones Treatment |
| Dormancy in some seeds is broken by treating them with hormones such as gibberellins, cytokinins and ethylene. |
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