- J Fivaz, I J Froneman and P J C Stassen
- Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspru it 1200, South Africa
- 1996
The phenological cycles of different litchi cultivars were studied from April 1993 until June 1995. The cultivars studied produced typical phenological cycles for “onyear” trees, with a high percentage of branches flowering. The “off-year” trees, on the other hand, flushed vegetatively during periods of inflorescence development and flowering. These vegetative shoots, which had not hardened off sufficiently for flower induction, produced further vegetative flushing which competed with reproductive growth. Fruit growth patterns, for the cultivars HLH Mauritius, Red McLean, Late Large Red, Fay Zee Siu and Brewster, were sigmoidal, with the aril growth starting 42 days after anthesis. In all the cultivars, two waves of fruit drop were identified. The first occurred two to three weeks after full female flowering, and the second at the time when the embryo and aril started growing.
Summary:
The study focused on the phenological cycles of different litchi cultivars in South Africa from April 1993 to June 1995 to develop a phenological model for better management of litchi production.
Typical growth includes annual vegetative growth followed by flowering and fruiting cycles, with a two to three month vegetative flush post-harvest, then a rest period before flowering.
On-year trees show high flowering percentages with little vegetative growth during flowering, while off-year trees show vegetative flushing during flowering that competes with reproductive growth, reducing yields.
Key cultivars studied include HLH Mauritius, Red McLean, Late Large Red, Fay Zee Siu, Brewster, Third Month Red, and Wai Chee across multiple locations.
Fruit growth patterns are sigmoid with aril growth starting about 42 days after anthesis; two waves of fruit drop occur—early after flowering likely due to fertilization failure, and later due to competition between embryo and aril growth.
Environmental factors such as temperature, humidity, and drought influence vegetative flushing and flowering, with drought reducing late flushes and improving reproductive growth.
Different cultivars exhibit unique phenological responses and require individual management strategies.
On-year cycles are characterized by no vegetative flushing during flowering and fruiting, which correlates with better yields; off-year cycles have competing vegetative growth during reproductive phases.
Nutritional factors, particularly nitrogen, phosphorus, and potassium, play a crucial role in reproductive success and yield, with nutrient depletion during heavy cropping influencing subsequent flowering.
Further research into carbohydrate cycling, photosynthesis rates, and root growth is recommended to refine management practices.
The study emphasizes the need for a litchi management calendar based on phenological observations to optimize irrigation, fertilization, and pruning aligned with cultivar-specific cycles.
Regular and frequent flowering ratings are advised for better understanding and timing of interventions.
The model aims to enhance South African litchi production by enabling more precise management of vegetative and reproductive growth phases.