Paclobutrazol--do you know the smart plant growth regulator for flowers and fruits?

Paclobutrazol--do you know the smart plant growth regulator for flowers and fruits?

Updated Jun 8, 2022 

Paclobutrazol is triazole plant growth regulator which can inhibit the synthsis of gibberellins. It can significantly reduce apica dominance and promote tillering, shorten the internodes, increase the content of chlorophyll,protrin and nucleicacid;paclobutrazol can control vigorous growth, prevent lodging, control shoots and promote flower. promote root development and increase the plant's resistance,increase yield significantly.


One method to manipulate flowering is to use the plant growth regulator, paclobutrazol. The post- harvest application of a small amount of paclobutrazol to the soil significantly promotes flowering and fruiting in the following year. Trials over the last two years have shown the following benefits from the treatment:

  • A significant increase in flowering leading to increased yields.
  • The early flowering considerably enhanced fruit maturity. Treated trees flowered three to four weeks early, which reduced the time to fruit maturity by at least two weeks.
  • Visually, the fruit developed a better external colour.

How does paclobutrazol act?

Available evidence strongly suggests that flower initiation depends on the presence of an unknown flower-promoting factor or factors synthesised in the leaves. At the same time, there are other factors in the shoots which work against the flowering factor or factors. It is believed that a group of plant hormones called gibberellins act as inhibitors to flowering. When paclobutrazol is applied to the soil, it moves up through the roots into the shoots and, due to its anti-gibberellin properties, blocks the synthesis of flowering inhibitors, thereby allowing the flower-promoting factor(s) to work.

How and when to apply paclobutrazol?

The application of paclobutrazol to soil as a drench around the tree trunk (collar drench) is the most effective method, as it ensures proper uptake by the tree. The required quantity is mixed in approximately one litre of water and poured onto the soil around the trunk in a circular band. In the Top End, the ideal time to apply paclobutrazol is from soon after harvest to early January. In dry conditions, a light irrigation is recommended after application. Foliar sprays have been ineffective

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