THAI TROPICAL LYCHEES – IDENTIFICATION OF CULTIVARS BY MORPHOLOGICAL METHOD

Lychee is classified as a subtropical fruit. However, there is a group of lychee trees in Thailand which flower under the tropical climate of central Thailand. This group of lychee trees would be more accurately classified as tropical fruit trees. Tropical lychee trees flower after experiencing temperatures of 14-19°C for a continuous period of 110-120h. There are at present about 20 cultivars of tropical lychees in Thailand, of which 'Khom' is the main cultivar due to its attractive commercial properties. 'Khom' accounts for over 90% of all tropical lychees grown in Thailand. Ninety percent of 'Khom' trees are planted in one single province, Samut Songkram, which is about 70 km west of Bangkok. 'Khom' accounts for about 8-10% of the total annual lychee production in Thailand. 'Khom' is harvested in early April, about 4 weeks before the harvest of the normal subtropical lychees. 'Khom's retail price is on average about 75% higher than that of Hong Huay, the most popular subtropical lychee cultivar in Thailand. The above statistics clearly show that 'Khom' is commercially attractive. As the same tropical lychee cultivar, planted in different regions, may have different names, this creates some confusion. Morphological studies of 10 tropical lychee cultivars reveal distinct difference in leaves, number of compound leaves, leaf tip and leaf perimeter. This suggests that morphological character can be used to identify each tropical lychee cultivar.