Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 89, A1

Compensating 'Hidden Hunger' of calcium for improved yields and enhanced quality crop

ITC - ILTD Division, Rajahmundry, India.
Except for an odd plantation, calcium deficiency is not observed in irrigated Northern Light Soil (NLS) flue-cured tobacco crop in India. Even the levels of calcium in the cured leaf are reasonable. However, recent studies (1995-99, 99-00) indicate positive response to calcium foliar application, which explains the 'hidden hunger' of the plant for calcium. Also the calcium detected in the cured leaf is probably utilised for cell wall formation and sufficient quantities are not available for other plant metabolic processes. Being immobile, exogenous supply of calcium, as a foliar spray, has helped in contributing favourably to crop growth and enhancing quality - especially of top half of the plant. A calcium enriched micro nutrient solution consisting of 450 ppm of calcium (16% Ca) when sprayed during grand growth period around 50th-55th day, gave 7% of higher yields (165 kg/ha). The nicotine and total sugars balance has improved significantly (from 2.90% nicotine and 18.6% total sugars to 2.52% nicotine and 22.13% total sugars in lower stalk position and from 3.0% nicotine and 19% total sugars to 2.64% nicotine and 22.45% total sugars in the upper stalk position). Higher levels of calcium up to 900 ppm (2 sprays) resulted in a suppressed plant growth, whilst improving top grade outturns by 6-7%. The other micro nutrients include magnesium (3%), zinc (2%), boron (0.3%), iron (0.75%), copper (0.25%) and manganese (0.10%). Higher levels of micro nutrients resulted in producing more 'luggy' leaf with brighter colour. Details of grade outturns, physical parameters, accumulation of nutrients in the cured leaf at different plant positions and other physical and biochemical changes will be discussed in the paper.