Botanical name of clove is Syzygium aromaticum.
Clove of commerce is the dried aromatic, fully-grown but unopened flower buds. Clove is an evergreen tree and it has been used as a spice in India since time immemorial. Clove is an evergreen tree of humid tropics. Clove can be grown in all the areas of the country except in the coastal sandy belt. But the red soils of Kerala and the hilly tracts of the Western Ghats are best suitable for its cultivation.
Rich, loamy soils of the humid tropics are the ideal soil for the commercial cultivation of clove trees.
Seed propagation is commercially practiced in clove. Seeds are collected from selected ripe fruits of the ‘mother tree’ and then they are soaked overnight before sowing them in the nursery beds.
Seed pericarp is removed before sowing. It is advisable to sow the seeds immediately after harvesting. Another propagation method adopted for commercial cultivation of cloves is ‘approach grafting’. Approach grafting of clove on its own rootstock is successful.
RAISING OF SEEDLINGS
Nursery beds of loose soil-sand mixture having 15–20 cm height, 1m width and convenient length are made. Afterwards, 5–8cm thick snad layer is spread and then seeds are sown at 2 cm spacing. The seed beds are protected from direct sunlight by providing adequate shade. Seedlings can be raised in polybags also. Seeds are directly sown in polybags filled with soil and cow dung mixture and then kept in a shady, cool place. The germination commences in about 10–15 days and may last for about 40 days. The germinated seedlings are transplanted in polythene bags (30cm × 15cm), containing a mixture of soil, sand and well decomposed cow dung in a 3:3:1 ratio.
The seedlings are again transplanted after one year to large polythene bags containing the same potting mixture. The 18–24 months old seedlings are ready for transplanting in the main field. The nurseries are usually shaded and irrigated daily to ensure uniform seedling stand.
Nursery bed treatment
Crickets are a common problem and to avoid damage by crickets, 5% BHC dust may be applied in the nursery.
Ideal time for planting is at the onset of South-West monsoons (June-July). However in low-lying areas, ideal time for planting is towards the end of monsoons. The pits of 75cm × 75cm × 75cm size are dug at a spacing of 6–7m. If planted as an intercrop, the spacing is to be adjusted based on the spacing of the major crop. The pits are partially filled with compost, green leaf or cattle manure and covered with top soil. Clove prefers partial shade. It comes up well at higher elevations, having well-distributed rainfall. Under Indian conditions, it is best suited for mixed cropping in older coconut or area nut gardens or in coffee estates.
Training and Pruning
Training and pruning are not recommended in clove plantations.
Apply 50kg manure or compost and bone-meal or fish meal to a bearing tree/year. Organic manures can be applied as a single dose at the onset of the rainy season in trenches dug around the tree. The application of inorganic fertilizers @ 20g N(430g urea), 18g P2O5 (110g superphosphate), and 50g K2O (80g of muriate of potash)/year is recommended. The dose can be increased to 300g N (600g urea), 250g P2O5 (1,560g superphosphate) and 750g K2O (1,250g muriate of potash)/year for a grown-up tree of 15 years or more. The fertilizers must be applied in 2 equal split doses in May–June and September–October in shallow trenches dug around the plant normally about 1–1½m away from the base. The plant basin must be always kept weed free and mulched.
Irrigation is necessary in the first 3–4 years. Extreme care should be taken to keep a minimum soil moisture level during summer months. Plant based water application has to be followed.
Flowering of trees starts from the fourth year of its planting (under good soil and management conditions). But full bearing stage is reached only after 15 years. The flowering season is September–October in plains and December–January at high altitudes. The unopened buds are harvested when they begin to turn pink. At this time, they are less than 2cm long. The opened flowers are not valued as a spice. Harvesting should be done using step ladders without damaging the branches, as it adversely affects the succeeding growth. It is a common practice among the growers not to leave the trees to bear fruits as it has an adverse effect on subsequent tree growth.
POST HARVEST MANAGEMENT
Individual flower buds are separated from the cluster by hand and spread in the drying yard for drying. The correct stage of drying is when the stem of the bud becomes dark brown and the rest of the bud lighter brown. Well-dried cloves are only one-third the weight of the original. About 11,000–15,000 dried cloves are required to weigh one kilogram of the product.