Origin and distribution
The chestnut is commonly known as European chestnut, Italian chestnut, sweet chestnut and belongs to the family Betulaceae. The sweet chestnut is a native of Mediterranean countries of southern Europe and Asia Minor. It is the only species of chestnut which has been successfully introduced to the Himalayas and other temperate parts of India during the colonial period and found planted around dark-bungalows, botanical garden and official government compounds as an ornamental tree. It is also found in Nepal and Bhutan but to a lesser extent.
Sweet chestnut trees are monoecious, large, 20-30 m tall with a large crown spread. The bark is smooth when plants young. The leaves are oblong-elliptic 15-16 cm long with coarsely toothed margin and hairy. The flowers lie in spikelet-like creamy catkins. Nuts are dark brown with light-colored stripes. The pellicle is more fibrous and frequently folded into the folds of the kernel and thus removed with difficulty.
The prickly fruit called as ‘Burr’ enclosing 1-5 nuts each 1.25- 2.5 cm in diameter. The burrs turn yellow-brown and split open in 2-4 sections. Nutritional value and uses: Among all the major nuts, only chestnuts have a very low-fat content and consequently, can be processed by boiling, drying and stored at moderate temperatures without the problem of rancidity. The fruits are eaten raw, but generally, they are cooked by steaming in earthen pots after removing outer shell and consumed with salt and milk. Roasted nuts are also eaten like a roasted potato. In France, candied chestnuts are sold. Chestnuts are often added to animal fodder.
Sweet chestnut can be cultivated in the mid to lower elevations of the Himalayan region. It requires low chilling and grown on a wide range of soils but thrives well in drained, deep and fertile soils. Adequate soil moisture ensures proper growth and production of quality nuts. It is propagated by seeds, but established cultivars are raised by vegetative method also. For seed propagation, the nuts are kept in moist sand at 00C or 20C for two months for stratification which ensures good germination.
They are sown in the nursery beds at 5-7 cm deep, and 15 cm apart rows at a distance of 90 cm. Usually, taproots are cut below the ground level at 20-25 cm at least a year before transplanting to avoid mortality while uprooting the plants. Budding and grafting are also done for the propagation of chestnut; however, budding is not widely practiced because of low success rate. Tongue grafting onto the stock of the same diameter, however, give better most success.
Planting is done in pits of one cubic meter in size, filled with a mixture of soil and farm yard manure. The best time of plantation is December-January. The planting is done in 8 x 8 m distance. The plant raised by cuttings from one-year-old wood produces more shoots. Thus the trees should be trained as single stem up to a height of 1.5 m. Practically, no pruning is done in sweet chestnut. To harvest good yield, doses of FYM @ of 20-25 kg and 500 g NPK in the ratio of 1:2:1 may be applied /tree per year.
Sweet chestnuts trees are monoecious; staminate flowers appear on cylindrical catkins while Pistillate flowers arise at the base of one or more bisexual catkins on current season shoots. Flowering takes place in the month of March-April and fully developed fruits in August-September. The nuts fallen from involucres to the ground should be collected and dried.
Genetic Resources Management
Two accessions of sweet chestnut namely IC019400 and IC019402 collected from Uttarakhand are being maintained in the field gene bank. However, there are a large number of cultivars viz. Abundance, Nanking, Meiling, Orrin, Crane, Sleeping Giant, Hemming, Willoka and Jersey Geneva are grown in different countries.
The genus Castanea has several other species, the important one are C. mollissima (Chinese chestnut), C. crenata (Japanese chestnut), C. sativa (European chestnut) and C. dentata (American chestnut)
- National Bureau of Plant Genetic Resources Regional Station Phagli, Shimla