Climate and soil
Nutmeg thrives well in warm humid conditions in locations with an annual rainfall of 150 cm and more. It grows well from sea level up to about 1300m above mean sea level. Areas with clay loam, sandy loam and red laterite soils are ideal for its growth. Both dry climate and water logged conditions are not suitable for Nutmeg cultivation.
Varieties and planting material
As Nutmeg is cross-pollinated,considerable variations are observed in the crop. The plants differ not only for all aspects of growth and vigour, but also for sex expression, size and shape of fruit and quantity and quality of mace. A good tree yields about 2000 fruits annually on an average, but the yield may vary from a few hundreds to about 10,000 fruits. Indian Institute of Spices Research, Calicut has selected a high yielding clone IISR-Viswashree which yields about 1000 fruits at the eighth year of planting. An average yield of approximately 3122 kg dry nut (with shell) and 480 kg dry mace per hectare could be obtained with a population of 360 plants/ha. The dry recovery of nut and mace of IISR-Viswashree is 70 and 35 % respectively. The nut has 7.1 % essential oil, 2.5 % oleoresin and 30.9 % butter,while the mace has 7.1 % essential oil and 13.8% oleoresin. Other varieties released are Konkan Sugandha, K.Sreemanthi and Konkan Swad from Dr.Balasahab Swant Konkan Krishi Vidya Peet, Dapoli, Maharashtra.
An important problem in nutmeg cultivation is the segregation of seedlings into male and female plants resulting in about 50 % unproductive male trees. Though there have been several claims that sex could be determined at seedlings stage on the basis of leaf form and venation, colour of young sprouts, vigour of seedlings and shape of calcium oxalate crystals on leaf epidermis, none of them is sufficiently reliable. The only alternative is to adopt vegetative propagation either by top-working male plants or using budded or grafted plants.
Nutmeg is commercially propagated through grafts. For raising root stocks, naturally split healthy fruits are harvested during June-July. The seeds are extracted from the pericarp and sown immediately in sand beds of convenient length, 1 to 1 ½ m width and 15 cm height. Regular watering is necessary for good germination. Germination may commence from about the 30th day and last up to 90 days after sowing. About20 day old sprouts are transplanted to polythene bags containing a mixture of soil, sand and cow dung (3:3:1).
The selected root stock at the first leaf stage should have a thick stem(diameter of 0.5 cm or more) with sufficient length so as to enable to give a cut of 3 cm length. Scions with 2-3 leaves, collected from high yielding trees can be used for grafting. The stock and scion should approximately have the same diameter. A ‘V’ shaped cut is made in the stock and a tapered scion is fitted carefully into the cut. Bandaging at the grafted region may be done with polythene strips. The scion is covered with a polythene bag and kept in a cool shaded place protected from direct sunlight. After 1 month, the bags can be opened and those grafts showing sprouting of scions may be transplanted into polythene bags, containing a mixture of soil, sand and cow dung (3:3:1) and kept in shade for development. The polythene bandage covering the grafted portion can be removed after 3 months.
During grafting, precautions should be taken to prevent wilting of scions and to complete the grafting as soon as possible. The grafts can be planted in the field after 12 months.