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Turmeric (Curcuma longa)

Agronomy and Cultivation of Turmeric

Growing conditions Turmeric is cultivated in the subtropical to tropical zone. In India for example it is usually grown in warm to hot, and perhumid to humid subregions, Optimum temperature ranges from 18.2 - 27.4 °C and optimum altitude ranges from 450-900 m above mean sea level. Turmeric can be grown at rainfall levels ranging from 64-429 cm. Depending on the distribution and the amount of rainfall, it is either grown as a purely rainfed crop (bimodal rainfall) or supported by irrigation (unimodal, low rainfall). In case it is grown as a rainfed crop, fairly heavy rainfall for the first 2 months after planting is essential for sprouting, root and shoot emergence, and enlargement of the crop. Ideally rainfall should amount to about 150 cm at sowing, remain fairly heavy and well distributed during the growing season and finally give way to dry weather about one month before harvest [1].

Soil should be well-drained, deep loamy to clay loam and further have high levels of major and secondary nutrients, high organic carbon content and base saturation with a pH ranging at about 4.3-7.5. Different soil types, which are grouped under Inceptisols, Entisols, Vertisols, Alfisols, and Ultisols have been found to be suitable for the cultivation of Turmeric.Coarse and heavy soils on the other hand can hinder rhizome development [1].

Planting Turmeric is propagated vegetatively for commercial production. Two types of rhizomes are distinguished, the “mother rhizome” and the “finger rhizome”. The latter is developed from the mother rhizome and also known as “daughter rhizome”. Depending on their position the fingers are considered primary, secondary or tertiary fingers. Both mother and finger rhizomes are good planting material and used for propagation, with different trends for different regions. A higher field performance is attributed to mother rhizomes, due to rapid growth, good development and higher yields. Farmers aiming for high yield should use either mother rhizomes or primary fingers. For mother rhizomes spacing of 45 cm x 30 cm was found to be the best planting sequence [1]

Harvesting The rhizomes can be harvested after 7 to 10 months, depending on the cultivar, soil and growing conditions [2]. The whole plant including the stem dries up, which indicates the maturity of the crop [1, 2]. It is also possible to harvest after full maturity if needed. „The rhizomes do not deteriorate if left in the ground for some months more“ [1]. Irrigation is usually stopped one month before the harvest, to allow the plant to dry [1]. The harvest is mostly done by hand. First, the stem of the plant is cut at the ground. Then the rhizomes are dug out. This can be done in different ways. However, there are also harvester machines available.

Sources [1] Nair KP. The Agronomy of Turmeric. In: Nair KP, editor. Turmeric (Curcuma longa L) and Ginger (Zingiber officinale Rosc) - World’s Invaluable Medicinal Spices: The Agronomy and Economy of Turmeric and Ginger [Internet]. Cham: Springer International Publishing; 2019 [cited 2022 Nov 12]. p. 85–103. Available from: https://doi.org/10.1007/978-3-030-29189-1_6 [2] Plotto A. Turmeric: Post-harvest Operations. Food and Agriculture Organization of the United Nations, 2004