engleski

Study of Growing Flue-cured Tobacco in Croatia under Various Conditions of Irrigation and Nitrogen Nutrition

Three field experiments were conducted at the experimental station of the Tobacco Institute Zagreb in Pitomača during the years 1990 and 1992, 1993 - 1996 and 1999 – 2000 to determine the effects of irrigation at different soil moisture levels (40-100%, 60-100%, 80-100% of PAW), of different starting times of irrigation (vegetative phase, early flowering stage, continuously), and of irrigation combined with nitrogen nutrition (0, 20, 40, 60 kg/ha N) on the yields and quality of flue-cured tobacco. The first two experiments were carried out using block methods and the third using the split-plot method. In the first experiment, irrigation led to an increase in yield (3-38 %), in price/kg (15-69 %) and in reducing sugar content (18-89 %) and a reduction of nicotine content (20-39 %) in the flue-cured leaves. Additional irrigation at the early flowering stage and constant maintenance of soil moisture at a higher level resulted in somewhat lower yields but better visually estimated tobacco quality and had a marked influence on nicotine and reducing sugars as expected. In the second experiment, irrigated tobacco gave higher yields in two of the four trial years, which were significant in 1995 (13-21 %), higher reducing sugar concentrations in 1994 (20-34 %) and a marked reduction of nicotine in cured leaves in all years (11-56 %). Under conditions identical or similar to those used in this research, irrigation may be started at the early flowering stage. In the third experiment, in both years irrigated tobacco showed significantly higher yields, price/kg and reducing sugar levels and significantly lower nicotine content. Averaging the two years, there were increases of 17%, 12 % and 26% and a decrease of 29 %, respectively. Higher amounts of nitrogen fertilizer promoted yield (up to 32 %) and nicotine content (up to 76 %), while decreasing reducing sugars (by up to 52 %). Also, the price/kg of tobacco fertilized with more than 20 kg/ha of nitrogen dropped by up to 26 %.

flue-cured tobacco; yield; price/kg; nicotine; reducing sugars

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