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Apical Dominance

a condition where vertical growth supercedes lateral growth in a plant. this is controlled by auxins, where in high concentrations can inhibit growth but on the whole promote it. Removal of the apex can induce lateral growth. Typically a shoot has leaves attached to a stem. The apex of the stem has an actively growing apical bud. It produces additional nodes and internodes to add to the length of the shoot. Additional leaves appear at the nodes as they are produced. In some plants, the lateral bud located in the axil of each leaf does not grow to form branches, especially at first. This condition is known as strong apical Dominance. apical Dominance is thought to be caused by the apical bud producing IAA (auxin) in abundance. This auxin is transported basipetally from the apical bud. The auxin causes the lateral buds to remain dormant. How could a lower concentration cause lateral buds to remain dormant and a higher concentration cause the apical bud to grow? This is explained in the following graph: The difference in response between the two kinds of buds is explained in their sensitivity to the auxin concentration. Clearly the lateral buds are more sensitive to auxin than the apical bud. There is a concentration of auxin at which the apical bud is stimulated to grow while the lateral buds are inhibited. That concentration would be near the letter "C" of "Concentration" in the graph above. When the apical bud is removed, the source of IAA is removed. Since the auxin concentration is much lower, the lateral buds can now grow. In fact their growth will be stimulated by a relativley small drop in auxin concentration. Thus, decapitating (pruning) a shoot will cause it to branch!


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Re:

... is driven by several factors... hmm what happens if auxin promotes apical dominance, then it cant grow anymore due to the limiting space?

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by duherro
Mon May 07, 2012 1:37 pm
 
Forum: Botany Discussion
Topic: Plant hormone experiment!
Replies: 17
Views: 6631

Re: Mitosis and Meiosis

... for them to grow. Easy experiment to that effect: cuting off shout apical meristem will result in no more growth of that shoot, no matter how ... of lateral shouts (which involve mitosis) due to the loss of apical dominance.

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by Cat
Wed Mar 12, 2008 1:14 pm
 
Forum: Cell Biology
Topic: Mitosis and Meiosis
Replies: 19
Views: 23634

Prune apical meristem and lower branches to increase yield?

... in regards to pruning and yield. We both agreed that pruning the apical meristem (a.k.a "topping") usually increases yield due to the diffusion of auxins which control apical dominance (AD). The resulting 'competition' of the remaining lateral shoots/branches ...

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by bta
Mon Aug 20, 2007 11:53 pm
 
Forum: Botany Discussion
Topic: Prune apical meristem and lower branches to increase yield?
Replies: 0
Views: 2231

Do the roots produce hormones rhizogenic

... Auxins Auxins are hormones involved in plant-cell elongation, apical dominance, and rooting Synthetic Auxins Chemists have synthesized several inexpensive compounds ...

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by SU_reptile
Fri Jul 21, 2006 9:17 am
 
Forum: Botany Discussion
Topic: Do the roots produce hormones rhizogenic
Replies: 3
Views: 2784


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