Litchi, the queen of fruits, is an emerging fruit crop of Pakistan. Litchi fruit is botanically called as Litchi chinensis and commonly called as leechi, litchi, laichi, lichu or lizhi. It’s a fresh and delicate fruit whitish pulp with an excellent perfume flavor usually lost during canning hence the fruit is mostly eaten fresh. It was introduced here in early 1932 by Sardar Faqir Singh from Dera Dune, India, and remained an exotic plant until 1960s when commercial production started from few orchards located near Begum Kot, Lahore of Punjab province. Owing to its good fruit quality and profitability in early 60s, large scale plantations expanded to North West Frontier Province (NWFP) (Harri Pur, Hazara and Khan Pur) and later to Sindh (Tando Allah Yar, Nawab Shah, Moro, Mir Pur Khas) province.
At present it is grown on an area of around 3000 acres with annual production of about 9250 MT. The main cultivars are Bedana, Calcutti, Dera Dune/Gola, Bombay, Chinese, Lychee Siah and Madrasi. Gola and Calcutti are two widely grown commercial cultivars, the former is consistent bearer while later shows alternate bearing habit. The litchi fruit is a good source of food, nutrition and has good medicinal value. It contains about 65 calories per 100 gram of fresh fruit. Litchi fruit is a good source of potassium (K) and nitrogen (N) but significant variations have been reported in N, P, K, Ca, Mg, Na, and Fe in different cultivars but, despite variation in cultivars, 100 g litchi fruit may contain 2-4 per cent of DRI (Dietary reference intake) for six minerals P, K, Mg, Fe, Zn, and Mn . Litchi with an average vitamin C content of 27.6 mg/100 g FW is regarded as good source of vitamin C, though cultivars may differ significantly in their Vitamin C content.
Litchi can be grown on a wide range of soil ranging from sandy loams, alluvial sand and calcareous soil, but grows best in alluvial sandy loam soils with good drainage. It thrives well in acidic loamy soils with abundant moisture and well drained clay soils. Fruits are mostly commercialized using mulberry baskets with 20-80 kg net weight. Harvesting season is well distributed and starts from May (Sindh) through June (Punjab) to July (NWFP province). The litchi plants generally require regular irrigation at intervals of 2-3 days. Efficient water management can overcome several physiological disorders such as poor sex ratio poor fruit set, heavy fruit drop. The litchi fruits are characterized by relatively short postharvest or storage life. The fruits are available only for 3-4 weeks in the months of June and July. After harvest, the pericarp of litchi fruits rapidly turns brown and brittle that leads to pericarp cracking which exposes the aril and provides entry to fungal pathogens resulting in rapid decay.The issue of extension in storage or marketing of litchi fruit is complicated by its high sensitivity to climatic conditions, pericarp browning and desiccation and the tendency of skin cracking which not only decreases the visual quality by promoting browning in exposed aril and hence decreases their marketability. The potential of litchi fruit have not been fully exploited in Pakistan. Due to hot dry weather during fruit maturation, pericarp (skin) cracking is very serious issue in litchi growing areas in Pakistan. Both pre and post-harvest treatments can be adopted to decrease; if not to eliminate, fruit cracking in litchi fruits. Nursery plants are propagated asexually through pot layering with 80 per cent success rate. System of irrigation is surface flooding. Over 95 per cent orchards are marketed through pre-harvest contractors. Over 90 per cent fruit is domestically consumed as fresh with little processing and negligible exports.
Due to hot dry weather, fruit skin cracking is the biggest issue in Southern Punjab. Main constraints for litchi production are lack of quality nursery plants, long juvenile period (7-8 years), and insufficient R&D based information for nutritional requirements, shortage of irrigation water and high post-harvest losses. Potential of litchi remains under exploit so far, better production infra-structure and post-harvest facilities are needed to boost industry for quality production and exports. With increased market demand, there is an ample opportunity for increasing the area under litchi as prevailing agro-climatic conditions have not been fully exploited. Based on the fruiting behavior, quality development and area under cultivation, the litchi growing districts could be grouped in a manner to take full advantage of climatic variability. However, to increase production and productivity, concerted efforts would be required for technological support and development of infrastructure.
The probable reasons for low yield are the narrow genetic base of the crop, non-availability of suitable superior cultivars, traditional production systems, poor technological support and incidence of insect pests, coupled with poor post-harvest management. The shortage of genuine planting material coupled with the long juvenile period of litchi is also the constraints. The low female/male flower ratio, premature fruit drop, and fruit cracking due to non scientific water and nutrient management also add to low productivity and production of poor quality fruits.
Litchi has a very narrow genetic base, which needs to be widened through selection of genotypes from the existing population. Target oriented programmes must be launched so that germplasm is conserved and used. A systematic approach for the description of cultivars is needed. Thus, a litchi descriptor needs to be developed. There is need to develop propagation technology for faster multiplication of quality plants. The development of nutrition management to maintain tree health and encourage successful flowering, fruiting and quality in sustainable manner, requires attention. Monitoring of nutrition in litchi through leaf analysis would be an approach for efficient fertilizer use. Integrated management of nutrient and water with efficient monitoring mechanisms would improve input use efficiency.
The authors are associated with the Institute of Horticultural Sciences, University of Agricultural Faisalabad, Pakistan.
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