Pg. 4-7 Litchi Phenology and Physiology

In order to obtain and maintain peak production and good quality fruit, correct amounts of nutrients for fruit trees should be applied during optimum periods. The uptake and distribution of micro- and macro-elements in a litchi tree alters during the different phenological stages of the tree and an understanding of these processes would provide valuable information about the time and rate of nutrient application required by a healthy and productive tree. The annual macro-nutrient requirement for a five-year-old litchi tree is 98.03 g nitrogen, 23.47 g phosphate, 123.1 g potassium, 110.32 g calcium and 39.23 g magnesium. 

Growth inhibitors were sprayed at the start of the second vegetative flush. Ethephon significantly increased flowering and also brought about significantly earlier flowering. In contrast, Sunny slightly delayed flowering but this delay was not significant. Pruning also delays flowering and this delay was significant. Calcium trials were started during the 1998/99 season and will be reported on during the next season when the results have been obtained. The aim of the trial is to improve post-harvest quality and investigate the effect of calcium on fruit size and yield.

Summary:

• The article discusses the importance of applying the correct amounts of nutrients to litchi trees during optimal periods for peak production and fruit quality.
• Nutrient uptake in litchi trees changes with phenological stages; understanding this helps optimize nutrient application.
• A five-year-old litchi tree requires annually approximately 98.03 g nitrogen, 23.47 g phosphate, 123.1 g potassium, 110.32 g calcium, and 39.23 g magnesium.
• Growth inhibitors like Ethephon significantly increase and accelerate flowering; pruning delays flowering significantly.
• Calcium trials aimed at improving post-harvest quality, fruit size, and yield are underway but results are pending.
• Phenology refers to annual growth and development cycles, while physiology studies the chemical and metabolic processes in the plant influenced by hormones and energy from sunlight.
• Vegetative and reproductive growth compete for resources; horticultural practices manipulate this balance for optimal crop yield.
• Management aims to establish a vegetative framework for light interception followed by maximizing fruit production and minimizing vegetative growth.
• Excess nitrogen or poorly timed nitrogen application can cause vegetative flushes that compete with fruit set.
• Calcium is vital for cell membrane structure, delaying senescence, pollen germination, inhibiting abscission, and delaying leaf senescence, but is poorly redistributed once deposited.
• Fruit calcium uptake is optimal during the first six weeks of fruit development.
• Growth inhibitors act by various mechanisms mostly inhibiting apical growth; Ethephon kills terminal buds and promotes flowering but also can cause leaf drop and nutrient deficiencies.
• Trials showed Ethephon treatments increase flowering but may impact fruit retention due to ethylene’s role in fruit abscission.
• The article presents data on nutrient distribution in different tree parts and emphasizes nutrient replenishment based on age and yield.
• Seasonal nutrient uptake data are incomplete, but nutrient application should be guided by soil and leaf analysis, tree appearance, and fruit quality.
• Growth inhibitors can allow higher density orchards and may improve flowering and fruit size if properly applied.
• The effect of calcium and growth inhibitors on final fruit yield and quality requires further study, with upcoming reports expected.