Tag: plant growth and development

Auxin is the phytohormone which is responsible for promoting apical dominance in plants. Auxin is usually seen at the growing tips of plants. Thus the auxin present at the tip of plants will be channelized sidewards, lateral meristem; so that the plants will not grow tall but instead becomes bushy in nature.

Auxins promote elongation of stem and coleoptile. It promotes the growth by the elongation of cells in the apical meristem. Growth in the lateral bud is inhibited when the apical bud of a tall plant remains intact. However, the lateral bud grows rapidly on the removal of apical bud. Suppression of growth in the lateral bud by apical bud due to auxin produced by apical bud is termed as apical dominance. IAA is an example of auxin. 

Auxins (like IAA) and gibberellins (GA) are growth promoting phytohormones. IAA promotes apical growth whereas GA causes internodal elongation. Promotion of apical growth by auxins and suppression of axillary growth is also called as apical dominance.

Apical dominance is a physiological response of auxins. The chemicals mentioned in options A, C and D are all auxins. They inhibit the growth of axillary buds and stimulate the growth of apical bud. This phenomenon is called as apical dominance. Gibberellins are also growth promoting phytohormones. They stimulate internodal elongation. Thus, bringing about an increase in length or height of plants.

Charles Darwin used cut tip of canary grass seedlings to demonstrate the sensitivities of the stem apex to light mediated movements. 

Auxins when applied to plant cuttings help in formation of adventitious roots. Higher concentration of auxin at apical bud suppresses growth of lateral bud having low concentration of auxin.

GA promotes the elongation of plants by inducing the division of lateral meristem. Whereas, the phytohormone auxin causes the apical dominance in plants. In the given options all other options other than gibberellic acid accounts for different types of auxin.

Greater growth on the shaded side of the stem is due to more accumulation of auxin on the shaded  side than on the illuminates. Auxin causes bending of plant towards light. Phototropism is induced by auxin hormone.

Apical dominance is a phenomenon in which main stem grows faster than the lateral branches. Apical bud produces auxin hormone that promotes apical dominance and inhibits growth of the lateral buds. When the apical bud is removed, the source of auxin is removed. Due to this, the lateral buds grow faster and makes plant bushy. 

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones produced in the tip of the shoot. Auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance.