SUBTROPICAL FRUIT
New study reveals ethephon’s role in regulating dormancy and flowering in litchi The Agricultural Research Council-Tropical and Subtropical Crops campus conducted research on optimising ethephon applications to completely inhibit any new shoot growth as opposed to frequent spot sprays for control of young flush, which are commonly used in the industry. Regina Cronje1, Elliosha Hajari1, Innocent Ratlapane1 and Arnold Jonker2 AGRICULTURAL RESEARCH COUNCIL-TROPICAL AND SUBTROPICAL CROPS 2 UNIVERSITY OF LIMPOPO 1
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uccessful flower induction and initiation in litchi are highly dependent on low temperatures (Figure 1). Litchi flower induction takes place in dormant buds of mature shoots and requires minimum temperatures below 15 °C. At flower initiation, the so-called while millet stage, temperature will determine whether a flower panicle will be pure, i.e. without leaves, or leafy (generally less fruitful). Shoot maturity is an essential prerequisite for flower induction in litchi and any new vegetative growth will reduce flowering.
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Traditionally, the plant growth regulator, ethephon, has been used in South Africa for spot spray applications to chemically remove such unwanted shoots. However, in the past decade, warmer winters have caused persistent vegetative shoot growth, which made the frequent use of spot spray applications less efficient and economical. In addition, inconsistent inductive temperatures have caused concurrent flower emergence, making growers hesitant to use ethephon out of concern that its application could damage already developing flower panicles. This necessitated a new approach to chemical flush control using ethephon. Therefore, scientists at the Agricultural Research Council-Tropical and Subtropical Crops campus conducted research on optimising ethephon applications to completely inhibit any new shoot growth prior to, and during, the flower induction period as opposed to frequent
VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021
