The Application Methods of Ethephon on Various Fruit Trees

Ethephon has many physiological effects on crops, such as inhibiting growth, inducing flower bud formation and flowering, controlling the sex of flowers, triggering organ abscission, and promoting fruit ripening. At the same time, it also causes various biochemical reactions.

1. Promoting Flowering

Ethephon can increase the activity of indole acetic acid oxidase in plants, delay the biosynthesis of IAA, reduce the IAA level in plants, and inhibit the activities of gibberellins and cytokinins. This helps achieve the goal of inhibiting the growth of branch tips and promoting flower bud differentiation. During the flower bud differentiation period, if the vegetative growth is excessive or does not stop, it will seriously affect flower bud differentiation. By treating with Ethephon, it can inhibit the growth of new branches of fruit trees or cause the new branches to wither and die, ensuring the normal process of flower bud differentiation.

Ethephon is applied to fruit trees such as lychee, longan, apple, mango, and green plum, and the results are very significant. Ethephon has a significant inhibitory or killing effect on the growth of winter shoots of lychee and longan. When used in combination with paclobutrazol and amino acids, it can significantly inhibit the growth of winter shoots and promote the increase in branch thickness. When combined with other plant regulators or cultivation measures, ethylenei has a very good effect on promoting flowering in apples. For example, 40% Ethephon at a concentration of 400 times + 85% B9 at a concentration of 400 times + ring-barking treatment on Red Fuji apples can effectively inhibit the growth of new shoots, improve the plant’s ability to flower, and significantly increase the single fruit weight and yield.

Ethephon treatment on fruit trees such as mango, green plum, and kiwi reduces the growth of new shoots. After treatment for 7-10 days, the new shoots of green plum and kiwi die, promoting flowering, increasing the fruit setting rate, and increasing the yield. Ethephon treatment on kiwi results in a flatter fruit shape, a significant reduction in fruit number, and ethylenei, whether used alone or mixed with B9 or PP333, has the effect of promoting the shedding of young fruits, significantly reducing fruit hardness and having a ripening effect. The effect of Ethephon on bananas is different from that on other fruit trees. It can increase the number of suckers absorbed by bananas, reduce fruit sparseness and fruit index, resulting in reduced yield.

II. Preventing “Overgrowth”

Both lychee and longan are mixed flower buds. When they start to bloom in spring and encounter high temperatures, the phenomenon of “overgrowth” often occurs. Especially for longan, if “overgrowth” happens, it will seriously affect the quality of flowers and yield. By treating lychee and longan with Ethephon, the growth of small leaves on the flower spikes can be inhibited, and pure flower spikes can be produced. Through experimental research on spraying Ethephon on black-leaf lychee, it was found that the purity of flower spikes and the average number of fruits per spike increased. The appropriate concentration of ethylene is 200-250 mg/L. When spraying 250-300 mg/L Ethephon on longan when the shoot grows 5-8 cm, it is beneficial for the differentiation of flower bud morphology and can prevent “overgrowth”, resulting in normal flower spikes.

When using Ethephon to treat the small leaves on the flower spikes, if the concentration is inappropriate, it often causes flower drop. In the experiment, it was found that changes in temperature and humidity during the budding period of lychee and longan would affect the effect of Ethephon. In the spring with low temperature and high humidity, the Ethephon concentration for preventing “overgrowth” is 250 mg/L; but in the spring with high temperature and drought, the Ethephon concentration for preventing “overgrowth” is 150 mg/L, which still causes flower drop, and the effect is the same on lychee and longan.

III. Ripening Promotion

Ethephon hormone can accelerate the decomposition of chlorophyll, promote the formation of anthocyanins, and cause the fruit skin to color, thereby accelerating the ripening process. Spraying 200mg/L Ethephon hormone 50 days after the full bloom of “Fisher’s Smile” fruit can significantly enhance the synthesis ability of anthocyanins, making the fruit color earlier, with a coloring area of 61%. Ethephon hormone has a certain effect on improving the coloring and ripening of large cherries, but its effect is slightly inferior compared to the treatment of borax + gibberellin. Treating European sweet cherries with 30mg/L Ethephon hormone can make the fruit mature 1-2 days earlier. Spraying 500-1000mg/L Ethephon hormone 2 weeks before the natural ripening of persimmons can promote the ripening process, making the fruit mature 1 week earlier without reducing the quality of the fruit. After ethylene hormone treatment, there is no significant effect on soluble solids, vitamin C, and fruit size, but there is a tendency to reduce the titratable acid content.

IV. Storage and Preservation

During the sale of fresh fruits, to extend the shelf life, Ethephon is commonly used to induce ripening of the fruits. After the fruits are treated with Ethephon, their color and flavor are better, but the usage concentration should be noted. When mangoes are stored in a cold room at 25-28℃ after being treated with 200 or 400mg/L Ethephon, the maturity characteristics of the mangoes are good. However, when treated with 600mg/L Ethephon, more of the fruit flesh Ethephon leaks out, resulting in deterioration of the fruit flesh tissue.