In rice fields, it is common to encounter a disease known as “bad seedling disease,” where the seedlings initially grow quickly, becoming tall and large. However, before long, some of the seedlings start turning yellow and may even die. This is a deadly enemy for rice cultivation.
Over thirty years ago, researchers began studying bad seedling disease in rice. They captured the main culprit—the fungus Gibberella fujikuroi (the pathogen causing the disease) and cultured it in a growth medium. Interestingly, if this culture medium was poured into rice fields, the growth rate of the rice immediately accelerated dramatically. Even when applied to tobacco, the plants grew exceptionally tall.
The secret was finally uncovered by Japanese pathologists Yabuta and Sumiki, who extracted a white crystalline substance from the culture fluid of the Gibberella fujikuroi—gibberellin. It turns out, gibberellin was the ‘notoriously wicked’ agent because a solution of it, diluted to one part per million, was enough to induce bad seedling disease in rice!
However, a bad thing can turn into a good thing. Now, gibberellin has become a very important plant growth stimulant in agriculture.
Gibberellin has a strong stimulating effect on plant growth, causing plant cells to elongate rapidly. This makes plants grow very quickly, sometimes five to six times faster than usual. The rapid initial growth of rice is due to the stimulation by gibberellin, but this fast growth makes the plants “externally strong but internally weak,” turning them frail. If its application is controlled artificially and supplemented with additional fertilizers, rice can grow quickly and robustly.
Gibberellin can also stimulate plants to flower and germinate earlier: normally, carrots and radishes go through a winter and only flower the following spring. If a few drops of gibberellin solution are applied to their leaves, they can flower within the same year! Typically, potatoes take about 100 days after harvest to sprout. If potatoes are soaked in a gibberellin solution, they can sprout in just 50 to 60 days.
Indeed, under the influence of gibberellin, many plants break conventional growth speeds. Nowadays, people cultivate the Gibberella fungus in a warm environment using a culture medium containing sucrose and other mineral nutrients to promote rapid reproduction. Then, gibberellin is chemically extracted from the culture medium.