- A J Joubert
- Navorsingsinstituut vir Sitrus en Subtropiese Vrugte, Nelspruit
- 1988
Om lietsjies van ‘n hoe gehalte te produseer is dit noodsaaklik dat kennis geneem word van die groeistad ia van die vrug en data lie bewerkingspraktyke daarby aangepas word.
Summary:
- Lychee trees bloom in spring with terminal panicles containing small, inconspicuous male and female flowers; overlapping flowering ensures pollen availability during female flowering.
- Fruit growth follows a sigmoid (S-shaped) curve with three main stages:
- Stage 1 (50-60 days): Development of skin, embryo, and seed coat; fruit mass about 2 g with 35% seed, 65% skin, negligible aril.
- Stage 2 (14-21 days): Seed lobes develop and aril formation begins; fruit mass about 7.5 g with equal parts seed, skin, and aril (~33% each).
- Stage 3 (35-42 days): Main aril development; fruit mass about 21.5 g composed of 74.5% aril, 14% skin, and 11.5% seed.
- The fruit reaches ripeness at approximately 21–22 g after around 100 days from pollination, showing little seasonal variation.
- Fruit drop mainly occurs during Stage 2, linked to embryo abortion; 7-20% of seeds are “chicken-tongue” (undeveloped), but these fruits mature normally and are favored for taste and size.
- Ripeness is judged by color, taste, and size; no artificial ripening methods are available for lychees.
- Fruit cracking occurs mostly in Stage 3 due to internal pressure of the rapidly expanding aril on the skin, which must stretch; cracking is caused by weak skin (from water/nutrient stress), skin injury (insect damage, hail, sunburn), or environmental factors like low humidity and high temperature.
- Cracks usually appear lengthwise and damage is associated with skin browning, which weakens tissue.
- To prevent cracking, growers should ensure optimal growing conditions during all developmental stages to minimize stress and external damage.