Seed Dormancy Questions in English

(A) Seed germination is the process by which a seed develops into a seedling.
For this process to occur,three primary environmental factors are essential:
$1$. Water: It is required for the rehydration of seed tissues and the activation of enzymes.
$2$. Oxygen (Air): It is necessary for cellular respiration to provide energy for growth.
$3$. Suitable Temperature: It is required for the optimal activity of metabolic enzymes.
Light is not strictly essential for the germination of most seeds,as many seeds can germinate in the dark (hypogeal or epigeal germination). Therefore,light is considered non-essential.

(A) Water is of primary importance for seed germination.
When the seed protoplasm absorbs water,the seed resumes vigorous physiological activities.
The embryo then bursts through the seed coats to initiate growth.
$O_2$ is also essential for aerobic respiration,which provides the energy required for these physiological activities.

(B) Dry seeds have a very low water content (low hydration).
Enzymes are proteins that require a specific aqueous environment to maintain their functional conformation.
In germinating seeds,the high water content (hydration) makes the enzymes more susceptible to thermal denaturation.
Conversely,in dry seeds,the lack of water stabilizes the enzymes,allowing them to withstand higher temperatures without denaturing.

(B) The upward translocation of nutrients occurs from leaves to developing flowers,buds,and fruits.
During the germination of seeds and tubers,stored food is mobilized and transported upward to the developing shoot system to support growth.
Therefore,a germinating seed shows a significant upward flow of nutrients to sustain its initial development.

(A) Seed germination begins with the imbibition of water by the hydrophilic substances of the seed coat.
As the seed coat becomes soft,the embryo cells are activated.
Stored long-lived $RNA$ molecules are utilized to synthesize enzymes and growth promoters.
Consequently,respiratory enzymes resume their activity,marking the initiation of metabolic processes.

(B) The correct answer is $B$.
Many plant species,including those in the families $Leguminosae$,$Malvaceae$,$Chenopodiaceae$,$Convolvulaceae$,and $Solanaceae$,possess very hard seed coats.
These seed coats are impermeable to water and oxygen,which prevents the embryo from imbibing water and initiating germination.
This physical barrier is a primary cause of seed dormancy in these legumes,requiring specific environmental conditions or mechanical/chemical scarification to break the dormancy.

(B) The correct answer is $B$.
Water is absolutely necessary for seed germination because it is required for the rehydration of the seed,which activates metabolic processes.
Water provides the essential medium for enzymatic activity,allowing the breakdown of stored food reserves into simpler forms that the developing embryo can use for growth.

(A) Seed germination is a process that requires specific environmental conditions,primarily water,oxygen,and a suitable temperature.
$A$. Mature seeds placed over wet cotton have access to moisture (water) and oxygen,which are essential for the metabolic reactivation of the embryo,leading to germination.
$B$. Soaked seeds over dry cotton will lose their moisture to the dry environment,hindering the continuation of the germination process.
$C$. Dry seeds over dry cotton lack the necessary water required to rehydrate the seed tissues and activate enzymes.
$D$. Seeds soaked in $5\%$ picric acid are exposed to a toxic chemical that inhibits biological processes and kills the embryo,preventing germination.

(C) Seeds require oxygen for the process of aerobic respiration,which provides the energy necessary for germination. When seeds are sown too deeply in the soil,the concentration of oxygen is significantly lower compared to the surface layers. Due to this deficiency of oxygen,the seeds cannot perform the metabolic activities required for germination and thus fail to sprout.

(D) Seed dormancy is a condition in which seeds are prevented from germinating even under environmental conditions normally favourable for germination.
$1$. Mechanical resistance of the testa (seed coat) can prevent the embryo from expanding.
$2$. Impermeability of the seed coat to water or gases like $O_2$ prevents the necessary metabolic processes required for germination.
$3$. Unavailability of essential factors like water and $O_2$ directly inhibits the physiological activation of the embryo.
Therefore,all these factors contribute to the delay or inhibition of seed germination.

(C) Parasitic plants like $Orobanche$ (broomrape) are obligate root parasites.
Their seeds require specific chemical signals to break dormancy and germinate.
These seeds germinate only in the presence of specific chemical exudates (such as strigolactones) released by the roots of the host plant.
This mechanism ensures that the parasite germinates only when a suitable host is nearby,increasing its chances of survival.

(B) . Scarification is a mechanical or chemical method used to soften or weaken a hard seed coat. This can be achieved through techniques such as chipping,filing,machine threshing,or the use of hot water,fat solvents,or $H_2SO_4$ to allow water and oxygen to enter the seed,thereby breaking dormancy.

(B) Seed dormancy is a state in which seeds are prevented from germinating even under environmental conditions normally favourable for germination.
In many legume seeds,the seed coat is physically hard and impermeable to water and oxygen.
This hard seed coat acts as a mechanical barrier,preventing the embryo from imbibing water and exchanging gases,which is essential for the initiation of metabolic activities required for germination.
Therefore,the primary cause of dormancy in these seeds is the hard seed coat.

(A) Newly harvested potato tubers do not germinate immediately because they are in a state of dormancy.
Dormancy is a period in the life cycle of a plant or seed during which growth and development are temporarily suspended.
This physiological state prevents the tubers from sprouting even when environmental conditions such as temperature and moisture are favourable.
This mechanism is an evolutionary adaptation that prevents the plant from growing during unfavourable seasons.

(D) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions.
Methods to break seed dormancy include:
$1$. $Scarification$: Mechanical or chemical abrasion of the hard seed coat to make it permeable to water and gases.
$2$. $Stratification$: Exposing seeds to specific environmental conditions like cold or warm temperatures to mimic natural cycles.
$3$. $Environmental$ $factors$: Altering light,pressure,and temperature conditions can trigger germination by signaling the end of dormancy.
Therefore,all the mentioned methods are effective in breaking or reducing seed dormancy.

(C) The seeds of $Nigella$ and $Lily$ are classified as negatively photoblastic.
This means that their germination is inhibited by the presence of light.
Therefore,these seeds germinate best in the dark.

(A) Quiescence is defined as the period of suspended growth or development in an organism due to unfavorable exogenous (external) environmental conditions,such as lack of water,extreme temperatures,or lack of light. Once the favorable conditions return,the organism resumes its growth. In contrast,dormancy is often controlled by endogenous (internal) factors.

(C) Quiescence is a state where a seed is unable to germinate because environmental conditions (like water,oxygen,or temperature) are not suitable,even though the seed is physiologically capable of germination. When water enters,the seed coat swells and the embryo expands,but if the conditions for metabolic activity are not met,it remains in a state of quiescence.

(B) Seed dormancy is primarily induced by the plant hormone Abscisic acid $(ABA)$.
$ABA$ acts as a growth inhibitor that prevents germination in seeds,buds,and underground storage organs,allowing them to survive unfavorable environmental conditions.
In contrast,Ethylene is often involved in breaking dormancy in certain seeds and buds.

(B) Abscisic acid $(ABA)$ is a plant growth inhibitor.
It plays a crucial role in seed development,maturation,and dormancy.
$ABA$ inhibits seed germination and promotes dormancy,which helps seeds withstand desiccation and other unfavorable environmental conditions.
Therefore,the presence of $ABA$ is responsible for inducing seed dormancy.

(B) Seed germination is the process by which a seed develops into a new plant.
Water is the most essential primary requirement for seed germination.
Water enters the seed through the micropyle,which leads to the swelling of the seed,the rupture of the seed coat,and the activation of enzymes necessary for metabolic activities.
Without adequate water,the seed remains in a dormant state.

(A) Seed germination is the process by which a seed develops into a new plant. The essential factors required for this process are water,oxygen,and a suitable temperature.
$1$. Water: It is required for the rehydration of the seed,which activates enzymes and softens the seed coat.
$2$. Oxygen: It is necessary for cellular respiration to provide energy for the growing embryo.
$3$. Temperature: $A$ specific range of temperature is required for the metabolic activities of the enzymes involved in germination.
Light is not universally required for the germination of all seeds; while some seeds (photoblastic) require light,many others germinate equally well in the dark. Therefore,light is not considered an essential factor for the germination of all seeds.

(C) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions. $ABA$ (Abscisic Acid) is primarily responsible for inducing and maintaining seed dormancy. Conversely,$GA$ (Gibberellic Acid) acts as an antagonist to $ABA$ and is responsible for breaking seed dormancy and promoting seed germination.

(D) Seed dormancy is a state in which seeds are prevented from germinating even under environmental conditions normally favourable for germination.
Causes of seed dormancy include:
$1$. Impermeable seed coat: The seed coat may be impermeable to water or oxygen,preventing the embryo from initiating metabolic activities.
$2$. Immature embryo: In some species,the embryo is not fully developed at the time of seed dispersal and requires a period of maturation.
$3$. Presence of chemical inhibitors: The presence of growth inhibitors like Abscisic Acid $(ABA)$ prevents germination until the concentration of these inhibitors decreases or is overcome by growth promoters like Gibberellins.
Therefore,all the given options are correct causes of seed dormancy.

(D) Stratification is a process of treating seeds to simulate natural winter conditions,which helps in breaking seed dormancy.
It involves exposing seeds to low temperatures and moist conditions for a specific period.
This process mimics the environmental cues that seeds undergo during winter,allowing them to germinate when favorable conditions return in spring.
Scarification involves physically or chemically damaging the seed coat to allow water and oxygen entry.
Vernalization is the promotion of flowering by a period of low temperature.
Chelation is a chemical process involving the formation of complex compounds with metal ions.

(A) The process of mechanically or chemically breaking,scratching,or altering the hard seed coat to make it permeable to water and gases is known as $Scarification$. This is a common method used to overcome physical dormancy in seeds with hard coats,allowing germination to occur.

(D) Bud dormancy is a state where buds are inhibited from growing even under favorable environmental conditions.
Thiourea is a chemical compound known to effectively break the dormancy of buds in various plants,such as potatoes and certain fruit trees,by stimulating metabolic processes and promoting sprouting.
$IAA$ (Indole$-3-$acetic acid) is an auxin,$2, 4-D$ is a synthetic auxin,and Zeatin is a cytokinin,which have different roles in plant growth and development.

(A) Scarification is a physical or chemical process that involves breaking,scratching,or altering the seed coat to make it permeable to water and gases. This is often necessary for seeds with hard,impermeable seed coats to initiate germination. Stratification involves exposing seeds to cold temperatures to break dormancy,while vernalization is the induction of flowering by exposure to prolonged cold.

(C) The viability of a seed is determined using the $TTC$ (Triphenyl Tetrazolium Chloride) test.
In this test,the living tissues of the embryo reduce the colorless $TTC$ to a red-colored compound called formazan.
If the embryo is alive,it will turn red,indicating that the seed is viable.
$IAA$ (Indole$-3-$acetic acid) and $ABA$ (Abscisic acid) are plant hormones,while $NADP$ is a coenzyme involved in metabolic processes.

(B) Stratification is the process of treating seeds to simulate natural winter conditions that the seeds must experience before germination can occur. Many seeds require a period of cold,moist storage (low temperature) to break dormancy and induce germination. This process is known as stratification.

(C) Seeds are classified based on their ability to withstand desiccation and low temperatures.
$1$. $Orthodox$ $seeds$ are those that can tolerate significant moisture loss (desiccation) and low temperatures,allowing them to be stored for long periods in seed banks.
$2$. $Recalcitrant$ $seeds$ are those that cannot tolerate desiccation or low temperatures and lose viability quickly if dried or frozen.
Therefore,seeds that show tolerance to moisture and temperature reduction are known as $Orthodox$ $seeds$.

(A) The correct answer is $A$ (stratification).
$1$. Stratification is the process of exposing seeds to low temperatures under moist conditions to break seed dormancy and promote germination. This mimics natural winter conditions.
$2$. Scarification involves the physical or chemical degradation of the seed coat to allow water and oxygen to enter,which helps in breaking physical dormancy.
$3$. Vernalization is the induction of flowering in plants by exposure to prolonged cold,typically applied to young plants rather than seeds.
$4$. Chelation is a chemical process used to make micronutrients more available to plants in the soil.
Therefore,the specific treatment of seeds under moist,cold conditions to break dormancy is known as stratification.

(B) Phenolic acids are chemical substances found in plants that act as inhibitors of seed germination.
They function by promoting seed dormancy,thereby preventing the seed from germinating under unfavorable conditions.
Therefore,phenolic acid is classified as a seed dormancy promoter.

(A) The process of exposing seeds to low temperatures under moist conditions to break their dormancy and promote germination is known as $Stratification$.
$Vernalization$ refers to the promotion of flowering by a period of low temperature.
$Bolting$ is the premature production of a flowering stem on agricultural and horticultural crops.
$Parthenocarpy$ is the development of fruit without fertilization.

(D) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions.
Gibberellins are a class of plant hormones that play a crucial role in breaking seed dormancy and promoting germination.
They act by inducing the synthesis of hydrolytic enzymes, such as $\alpha$-amylase, which break down stored starch into sugars, providing energy for the growing embryo.
Abscisic acid, on the other hand, is known to promote and maintain seed dormancy.
Therefore, $Gibberellic acid$ is the correct chemical used to overcome seed dormancy.

(C) Seed dormancy is a condition in which seeds are prevented from germinating even under favorable environmental conditions. This dormancy can be broken by natural methods (such as passage through the digestive tract of animals,microbial action,or exposure to specific temperature cycles) as well as by man-made methods (such as scarification,stratification,or chemical treatment). Therefore,option $C$ is correct. Option $D$ is incorrect because cabbages and carrots are biennial plants,not multi-annual.

(B) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions.
$Abscisic \ acid$ $(ABA)$ is a plant growth inhibitor that plays a crucial role in inducing and maintaining seed dormancy.
It acts as an antagonist to growth-promoting hormones like gibberellins,thereby preventing premature germination and allowing the seed to survive unfavorable conditions.

(C) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions.
$(I)$ Mechanical scarification (using knives or sandpaper) is a man-made method to break the hard seed coat.
$(II)$ Passage of seeds through the digestive tract of animals is a natural process (biological scarification) that helps in breaking dormancy,not a man-made method.
$(III)$ Chilling conditions (stratification) are often used to remove inhibitory substances,which is a technique applied by humans in nurseries or laboratories.
$(IV)$ Application of chemicals like gibberellic acid and nitrates is a man-made method to stimulate germination.
Therefore,only $(II)$ is a natural process and not a man-made method.

(B) Seed dormancy is a state in which seeds are prevented from germinating even under environmental conditions normally favourable for germination.
One of the primary factors responsible for seed dormancy is the presence of a hard and impermeable seed coat,which prevents the entry of water and oxygen required for metabolic activities.
Additionally,the presence of growth inhibitors like Abscisic Acid $(ABA)$ also contributes to dormancy.
Conversely,$GA$ (Gibberellic Acid) promotes germination and breaks dormancy.
Therefore,a hard seed coat is a physical factor that causes seed dormancy.

(C) Seed dormancy is a state in which seeds are prevented from germinating even under environmental conditions normally favourable for germination.
Even if the seed coat swells due to water absorption and the embryo is ready to grow,the seed remains physiologically inactive or dormant due to various factors like hard seed coats,chemical inhibitors,or immature embryos.
This state is known as seed dormancy.

(C) The process of exposing seeds to low temperatures in a moist environment to break seed dormancy and promote germination is known as $Stratification$.
This technique mimics natural winter conditions, which signals the seed that the harsh season is ending and it is safe to germinate.
$Vernalization$ (Option $A$) refers to the promotion of flowering by a period of low temperature, not the breaking of seed dormancy.

(N/A) Definition: Seed dormancy is a condition in which seeds fail to germinate even when external conditions (moisture,temperature,oxygen) are favorable for germination.
Explanation: This state is controlled by internal factors rather than external environmental conditions. The seed remains in a resting phase for a specific period.
Factors causing dormancy:
$1$. Impermeable and hard seed coat.
$2$. Presence of chemical inhibitors like $ABA$ (Abscisic Acid).
$3$. Presence of phenolic acids and para-ascorbic acid.
$4$. Immature embryo.
Methods to overcome seed dormancy:
$1$. Mechanical scarification: Rubbing the seed coat with sandpaper or using a knife to make it permeable to water and gases.
$2$. Chemical treatment: Using chemicals like $GA_3$ (Gibberellic acid) or nitrates to neutralize the effect of inhibitors.
$3$. Stratification: Exposing seeds to specific low-temperature conditions to break dormancy.
$4$. Environmental manipulation: Changing light and temperature conditions to trigger germination.
$5$. Natural processes: Microbial action or passage through the digestive tract of animals can also break the seed coat.

(N/A) Seed dormancy can be broken through natural processes or human-induced activities:
$1$. Mechanical Scarification: If the seed coat is impermeable, it can be broken by rubbing with sandpaper or using mechanical pressure to create pores.
$2$. Physical Methods: Vigorous shaking of seeds can also help in breaking dormancy.
$3$. Microbial Action: In nature, microbial activity helps in degrading the seed coat, thereby breaking dormancy.
$4$. Digestive Tract: Passing seeds through the digestive tract of animals can soften the seed coat due to the action of digestive enzymes.
$5$. Chemical Treatment: Dormancy can be broken by using chemicals like $Gibberellic \text{ } Acid$ $(GA_3)$ or nitrates, which neutralize the effect of growth inhibitors.
$6$. Environmental Factors: Altering environmental conditions such as light, temperature, and chilling treatments can effectively break seed dormancy.

(N/A) $\rightarrow$ Dormant seeds do not germinate for a specific period. This duration can range from days to months,and this specific time is called the $\text{Dormancy period}$.
$\rightarrow$ Reasons for $\text{Dormancy}$:
$(a)$ $\text{Impermeable seed coat}$: In many plants,the seed coat is impermeable to water (e.g.,$\text{Chenopodium}$,$\text{Trigonella}$,$\text{Melilotus}$),oxygen (e.g.,$\text{Brassica alba}$,$\text{Pyrus malus}$),or chemicals (e.g.,$\text{Xanthium}$).
$(b)$ $\text{Mechanical inhibition}$: In some plants,the seed coat is very hard,providing mechanical resistance to embryo development (e.g.,$\text{Capsella}$,$\text{Lepidium}$).
$(c)$ $\text{Chemical inhibitors}$: Some seeds produce inhibitors like $\text{Abscisic acid (ABA)}$,phenolic acids,coumarin,or short-chained fatty acids that obstruct germination. These can be present in the fruit (e.g.,$\text{Ferulic acid}$ in tomato juice),endosperm (e.g.,$\text{Xanthium}$),or seed coat (e.g.,$\text{Cucurbita}$).
$(d)$ $\text{Immature embryo}$: Seeds like wheat,barley,and oats require a period of rest to mature and develop the ability to germinate. During this time,they synthesize necessary hormones.
$\rightarrow$ Methods to break $\text{Dormancy}$:
$(1)$ $\text{Temperature treatment}$: Exposure to specific heat or cold to deactivate growth inhibitors.
$(2)$ $\text{Scarification}$: Weakening the hard or impermeable seed coat through mechanical abrasion.
$(3)$ $\text{Biological action}$: Microorganisms in the soil decompose and weaken the hard seed coat.
$(4)$ $\text{Leaching}$: Removing inhibitors using rain or irrigation water.
$(5)$ $\text{After-ripening}$: Allowing time for the embryo to reach maturity.

(B) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions. This state is maintained by various growth inhibitors.
$1$. Abscisic acid $(ABA)$,phenolic acids,and para-ascorbic acid are well-known growth inhibitors that promote seed dormancy.
$2$. Gibberellic acid $(GA)$ is a plant growth promoter that acts antagonistically to $ABA$. It helps in breaking seed dormancy and promotes germination.
Therefore,Gibberellic acid is not an inhibitory substance; rather,it is a stimulatory substance for seed germination.

(A) Seed dormancy is a state in which seeds are prevented from germinating even under favorable environmental conditions.
This process is regulated by various plant hormones.
Inhibitors like $Abscisic$ $acid$,$Phenolic$ $acid$,and $Para-ascorbic$ $acid$ promote seed dormancy.
$Gibberellic$ $acid$ $(GA)$ is a plant growth promoter that acts as an antagonist to these inhibitors and helps in breaking seed dormancy,thereby promoting germination.
Therefore,$Gibberellic$ $acid$ is not an inhibitor.

(C) As a seed matures,its metabolic activity slows down and it enters a state of dormancy.
During this process,the seed loses a significant amount of water,typically reducing its moisture content to about $10-15\%$ of its mass.
This dehydration is essential for the seed to survive unfavorable conditions and maintain its viability until germination.

(A) Seed dormancy is a state in which seeds are prevented from germinating even under environmental conditions normally favourable for germination. During this stage,the seed becomes desiccated,and the metabolic activity of the embryo slows down significantly to conserve energy and ensure survival until favourable conditions return.

(D) Seed germination is the process by which a seed develops into a new plant.
For successful germination,a seed requires specific environmental conditions,which include:
$1$. Moisture (Water): It is essential for the activation of enzymes and the softening of the seed coat.
$2$. Oxygen $(O_2)$: It is required for cellular respiration to provide energy for the growing embryo.
$3$. Suitable temperature: Most seeds require an optimal temperature range to trigger metabolic activities.
$CO_2$ (Carbon dioxide) is not required for seed germination; in fact,high concentrations of $CO_2$ can inhibit the process.
Therefore,$CO_2$ is not a favorable condition for seed germination.

(B) Seed storage is a critical process in agriculture and conservation. For seeds to remain viable for long periods,they must enter a state of metabolic inactivity known as seed dormancy. During this state,the moisture content of the seed is reduced (desiccation),which prevents metabolic activities and protects the seed from fungal or bacterial decay. Germination is the opposite of storage,as it involves the activation of metabolic processes,which would lead to the loss of viability if it occurred during storage. Therefore,attaining dormancy is the essential factor for successful seed storage.