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The introduction of Lychee and Longan
The lychee (Litchi chinensis Sonn.) and longan (Dimocarpus longan Lour.) are both subtropical trees from the Sapindaceae family and thought to be native to southern China. Both produce delicious fruit on evergreen trees that eventually grow to heights of more than 20m. The lychee fruit is a drupe, 3-4cm long and 3cm in diameter, covered by a pink/red roughly textured rind which covers an inside layer of sweet and sour, translucent white flesh which surrounds the inner seed. The longan fruit is similar to those of the lychee, but smaller, smoother, yelowish in colour and has only a sweet flavour and very little aroma. Both fruits have many culinary uses predominantly associated with dessert-type dishes and both can be sold fresh or canned.
The major world producers of lychee and longan are China, Thailand and Taiwan, however, important crops also exist in India and Vietnam with further expansion in these regions occurring as a result of increased demand created by increased regional wealth (Menzel and McConchie 1998).
Australia is a minor producer; however it has the advantage in the international market because it produces fruit during the northern hemisphere ‘off season' including the lucrative Christmas and Chinese New Year festivities (Menzel and McConchie 1998).
Pollen transfer in lychee and longan may be by a combination of autogamous self-pollination, wind or insects, however, for commercial crops pollination by insects (in particular by the honey bee) is considered crucial to obtain a good yield (Badiyala and Garg 1990; DuToit 1994; McGregor 1976; Menzel and Waite 2005).
This case study is the primary source of information on potential pollination services for the industry. It is based on data provided by industry, the ABS and other relevant sources. Therefore, information in this case study on potential hive requirements may differ to the tables in the Pollination Aware report (RIRDC Pub. No. 10/081) which are based on ABS 2008 Agricultural Commodities Small Area Data, Australia 2005-06.
Pollination in lychee and longan
Self-pollination may occur in lychee, however, flowers are generally recognised as self-sterile and require insects to transport pollen from anther to stigma for fruit to set (Badiyala and Garg 1990; DuToit 1994; McGregor 1976). Only partial overlapping between male and female flowering occurs within a cultivar and so inter-planting of at least two different cultivars is necessary for adequate fruit set. Several insects have been reported to visit lychee flowers overseas including Coleoptera, Hemiptera, Homoptera and Lepidoptera; however, the honey bee has been widely recognised as the principal pollinator (McGregor 1976). In Australia, both honey bees and Trigona spp. were found on lychee blossoms, but preliminary studies suggest that Trigona may be too small to be effective pollinators of the fruit (King et al. 1989).
There have been few studies relating to longan flowering and subsequent pollination, although its botany is similar to that of the lychee (Menzel and McConchie 1998). As with lychee, there is an overlap of flower types on individual trees, since not all inflorescences develop at the same time. Pollination is similarly carried out by insects from early morning to mid-afternoon, particularly by the honey bee and unlike the lychee, longan crops have been shown to be effectively pollinated by Trigona species in Queensland (Blanche et al. 2006).
Many studies have shown significant increases in yield of lychee crops as a result of honey bee pollination. Badiyala and Garg (1990) introduced four honey bee colonies into a lychee orchard in India at the start of flowering and recorded fruit set two to three times higher in inflorescences open to honey bees compared to those that were bagged to exclude them. Similar results were recorded in South Africa by DuToit (1994) with a fruit set three times greater when inflorescences were open to honey bees. In Queensland, Blanche et al. (2006) established that pollen transfer in longan is by a combination of self-pollination and pollination by wind and bees. Both honey bees and stingless bee (Trigona spp) visited the flowers, however, only stingless bees, which were in high numbers due to a nearby rainforest, were found to have a positive relationship with fruit set. On the other hand, upward of 30% increases to longan yields have been reported in Thailand as a result of honey bee pollination (DAF 2005).
Lychee and longan yields are commonly unreliable, erratic and rarely approach the capacity of the tree. Crossed fruit are generally heavier and yields in rows with two cultivars adjacent to each other have been shown to be 36% higher in lychee (McGregor 1976). All of these studies clearly show that lychee and longan require at least one other cultivar and an abundance of insect pollinators for pollen transfer. Although Trigona species have been shown to be good pollinators of longan in Queensland when an orchard is near a rainforest, bringing in honey bee hives could be necessary to increase pollinator numbers, increase crossing between cultivars and produce a good quality yield.
Xiamen Kingfood Import &Export Co.,Ltd.
Xiamen Kingfood Import &Export Co.,Ltd.