Longan fruit is long known as a famous treat, and is the pride of the people of Hưng Yên. Grown along the Red River, Hưng Yên longan fruit has existed for nearly 300 years and is a part of the history of the town of Hiến. In the Pagoda of the town of Hiến there is the oldest longan tree which is considered as the ancestor tree. A stele was made in honor of the tree. The folklore tells a story of an official who traveled through Hưng Yên in the longan season. He tasted the fruit and experienced an unforgettable flavour. Knowing this is a valuable fruit, the official offered this fruit to the King, and ever since longan has been known as the fruit for Kings. Lê Quý Đôn, a famed scholar, when tasted the longan offered to the King, described the fruit: “the pulp is mouthful thick and the flavour is as holy water”. The distinctive flavour and characteristics of the longan fruit is well-known in daily lives as well as folk poems and songs:
“No matter if you travel North or East
The taste of Hưng Yên longan is unforgettable”
“Our land is the land of love
Our land is the land of longan”
“Sunrise on the Red River
Green shade of longan tree fills the field”
Hưng Yên longan has a prominent and easily noticeable characteristics. The fruit has a round shape, with dark-brown skin, the diameter is from 25.61 to 29.36 mm, the height is from 23.98 to 27.61 mm, the weight is from 9.35 to 13.28 gram per fruit. Vitamin C content is from 45.12 to 59.32 mg per 100 gram, total organic acid percentage is 0.04 – 0.17 %, total sugar percentage is from 13.89 to 17.37%, total soluble solids content is from 17.63 to 20.88 Brix, water content is 18.38 – 22.09. The taste of Hưng Yên longan is distinctive, with fresh and soft aroma, the pulp is thick, dry and transparent with crispy texture and sweet flavour.
The reputation and characteristics of Hưng Yên longan are attributable to the geographical condition suitable to the development of longan trees and the experiences of the people. The area growing Hưng Yên longan has a flat terrain alongside the Red River and Luộc River which has rich soil. The topography is inconsistent, sloping from North-West to South-East, with sunken boxes that are usually filled with water, forming strips, zones and areas with height differences which intertwine into wave formation. Soils for growing longan are Dystri-Haplic Fluvisols, Eutri-Haplic Fluvisols, and Areni-Hapli Fluvisols. The soil’s mechanical composition is from loamy sand to sandy loam. The soil has neutral reaction, pHKCL between 6.8 and 7.7. The Organic carbon and total protein content at average level. Total phosphate content and bio-available phosphate content are ranging from average to very rich. Annual average rainfall is from 1,300 to 1,700 mm, which is a high rate of rainfall. Annual average temperature is 20 - 24oC. Annual average humidity is 80 - 85%. Annual average evaporation is 1.000 – 1.100 mm.
The experiences of the people has significant contribution to the renowned reputation of Hưng Yên longan. Not only possessing long-established growing and tending techniques, the farmers here also embrace and apply new science and technology in tending, harvesting and processing to create high quality products. The farmers have learned how to choose high quality and highly productive longan trees for grafting, to choose Spring and Autumn which have high humidity and rainfall to grow new trees for better survival. The farmers have also learned to breed honeybee for better pollination, cutting winter leaves, branching, hoeing around the tree canopy in order to hinder the development of the trees to create the best condition for blooming flower and bearing fruit. Moreover, the farmers pay attention to cutting branches, young leaves, flowers and fruits in order to harvest the best longan fruits, and other know-hows for the unique longan of Hưng Yên.
Geographical area: Hưng Yên City, the districts of Khoái Châu, Tiên Lữ, Kim Động of Hưng Yên Province./.