Plant Growth and Hormones

ABA hormone is formed during leaf fall. It is a growth inhibiting hormone in plants which accelerates aging and inhibits germination and flowering. It also causes the closing of stomatal pore.

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. During abscission, high synthesize of ethylene is observed along with decrease in the concentration of auxin. Ethylene synthesizes enzymes like cellulase and pectinase which are involved in cell wall degradation. These enzymes loosens the cell wall and cells separate which ultimately leads to leaf abscission. 

Abscisic acid a plant hormone that plays important role abscission of leave. It inhibits stem elongation by inhibiting gibberellic acid. It prevents loss of dormancy in seeds. 

Abscisic acid is a plant hormone. It is also called as stress hormone. It causes abscission of leaves. During stress environmental condition, its concentration increases and induces bud dormancy. When favorable condition returns, bud dormancy is broken.

Ethylene is a plant growth regulator. It is also called as ripening hormone as it is responsible for speeding up ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. 

Abscisic acid is a plant hormone. It is also called as stress hormone. During stress condition like drought, abscisic acid concentration increases in plants. It inhibits cell division and induces bud dormancy. It also helps in abscission of leaves and hence the name given. It also stimulates senescence in plant.

Abscisic acid is a phytohormone which act as plant growth inhibitor. It is used to maintain the dormancy of seed. It inhibits the germination of seeds in adverse condition and ensures seed germination in favourable condition only.

Ethylene is a plant hormone. It is also called as ripening hormone as it is responsible for ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. 

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. It increases the tolerance of plants toward various stresses. It is found in high concentration in roots during drought and later translocated to leaves. It causes stomatal closure during water stress. It also promotes seed dormancy under adverse condition.

GA is Gibberillic acid a plant hormone which causes foolish seedling disease in which plants grow really tall because of the internodal growth. Gibberillic acid has been reported to induce pollen sterility in many plants like sunflower, rice etc. Ethylene is a volatile hormone which induces senescence and fruit ripening. Thus, the correct option is C. 

Senescence is the process by which cells stop dividing and growth is arrested without undergoing cell death. It is also called as ageing. Abscission is also called as fall. Shedding of leaves, flowers or fruits due to change in hormone balance in plant is called as abscission. Photoperiodism is the phenomenon in which formation of flowers in plants depends on the relative length of dark or light periods. Vernalization is the process by which plant can be induced to flower by exposing it to the prolonged period of low temperature or cold. 

Abscisic acid is a plant hormone. It is also called as stress hormone as it protects the plants under stress condtion. During unfavourable environmental condition, it causes bud and seed dormancy. Only under favourable condition, the seed dormancy is broken. It also causes retardation of growth. Also, it causes abscission or fall of leaves and hence, the name given.

A 2 ,4-D is an synthetic type of auxin, a plant hormone. It acts as weedicide as it kills weeds. Benzaldehyde is a synthetic growth regulator. It acts as pesticide. NAA is a synthetic type of auxin, a plant hormone. It acts as synthetic growth regulator. It acts as rooting agent. Ethylene is a gaseous plant hormone. It acts as natural growth regulator. It hastens the ripening of fruits. 

Abscisic acid is a plant hormone. It is involved in various physiological processes of plant. It promotes abscission of leaves and hence the name given. Its concentration increases as plant ages and ultimately results in the leaf fall. It is involved in the ageing process of plant.

ABA (abscisic acid) is a plant hormone. It is also called as stress hormone as its concentration increases during stress condition. During adverse environmental conditions like drought, it induces stomatal closure. This results in reduced transpiration rate during water stress condition.