Original scientific paper
Effect of topping height and maturity on the quality of flue-cured tobacco cultivars
2019, 20 (3) p. 841-851
Investigations of the topping height, maturity and tobacco cultivar on the price and quality indices, as expressed by reducing sugars/nicotine, total nitrogen/nicotine and N-protein/total nitrogen ratios, were conducted during 2004 - 2005 and 2007. Trial treatments included: (1) topping height (17 and 20 leaves for harvesting), (2) leaf maturity at harvest (unripe, ripe and overripe) and (3) cultivar (HVT 1, VJ 1, DH 17). Investigation results showed that precipitation deficiency in 2004 resulted in a decrease of overripe tobacco prices, while water stress at the intensive growth stage in 2007 caused a significant price increase from unripe to overripe tobacco harvesting. In the first two trial years, the best reducing sugars/nicotine ratios were achieved by overripe tobacco harvesting. In 2007, delayed maturing of tobacco led to irreparable disruption of the reducing sugars/nicotine ratio, below acceptable limits, irrespective of leaf maturity at harvest. The total nitrogen/nicotine ratio was within the limits for good-quality tobacco in all trial years, while higher ratios were recorded in the climatically most favourable year 2005 also in tobaccos with higher topping. The N-protein/total nitrogen ratio was in the range acceptable for that ratio in ripe tobacco leaves and in overripe tobacco leaves only in the extreme 2007. Significant impact of cultivar genetic variability on all the studied traits was established. It is also obvious from the results that irreparable impairment of the tobacco leaf chemical quality in 2007 was manifested only in the reducing sugars/nicotine ratio. Strong correlations were found between the reducing sugars/nicotine and N-protein/nitrogen ratios and weak correlations with the total nitrogen/nicotine ratio.