Abstract
After pollination, aborted date fruits known as tricarpel or shiss, remain on the brunch in most of the varieties and exert competition on fruits in water and nutrients. In Sukkary, they drop down at the end of kimri stage, while remain on ‘Khlass’ until the harvest. Most of them remain as bisr and little turns into tamr which is not appreciated in the date market. They can only be used as paste that has low price compared to dates. In an attempt to get rid of shiss, we sprayed Ethephon at different concentrations on bunches of ‘Sukkary’ and ‘Khlass’ after fruit-set, at hababook stage.Together with the shiss drop, a non-desirable fruit drop also occurs. We are looking for the optimum ethephon concentration where shiss dropped more than fruits. In ‘Khlass’, the Ethephon concentration 800 ppm showed the highest shiss drop (81%) together with a fruit drop of 20% that occurs as well, while in ‘Sukkary’, the concentration of 600 ppm was the best by giving shiss drop equal to 44%together with a fruit drop equal to 12%. We consider that the concentration of 800 ppm at hababook stage is the ideal concentration to generate an optimum drop in shiss with a reasonable percentage of fruit drop. We, therefore highly recommend a trial with this concentration on ‘Sukkary’ as well.
Highlights
The Ethephon or the 2-chloroethylphosphonic acid (CEPA) is a systemic plant growth regulator, which in its liquid state at the proper pH does not yield ethylene; when the pH is elevated, it breaks down to form ethylene (Arteca, 1996)
For the control where pure water is sprayed on the bunches, 4% of the shiss dropped, together with 8% of fruit drop
The concentration of 1,000 ppm Ethephon, despite generating a desirable high shiss drop, significantly different from the one generated by the concentration of 600 ppm Ethephon, but it did the same for fruit drop (Table 1)
Summary
The Ethephon or the 2-chloroethylphosphonic acid (CEPA) is a systemic plant growth regulator, which in its liquid state at the proper pH does not yield ethylene; when the pH is elevated, it breaks down to form ethylene (Arteca, 1996). At pH higher than 4, it breaks down to ethylene, hydrochloric and phosphatic ions. It stimulates the endogenous ethylene production by releasing ethylene in the plant tissue as the cell cytoplasm has a pH higher than 4 The main role of ethylene is to make changes in fruit texture, softening, colour, and other processes involved in ripening. It is known as the aging hormone in plants. Ebert and Bangerth (1982) reported that ethylene inhibited the synthesis and translocation of Indole-3-Acetic Acid (IAA) within the fruits, reducing sink strength and inducing the separation area in the peduncle, which causes fruit drop (Roberts et al 2002.)
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