Medium and trace element contents in flue-cured tobacco and their spatial distribution of part of Zunyi City, Guizhou Province

Objectives As the essential nutrient elements for tobacco growth and development, medium and trace elements play an irreplaceable role in the coordination of tobacco plant physiology, formation of flue-cured tobacco yield and quality, and enhancing the capacity of resistance. The study investigates the characteristics and spatial distribution of medium and trace elements in flue-cured tobacco leaves from some tobacco growing areas of Zunyi by using tobacco leaf nutrient information, to supply scientific references on the management of tobacco nutrient partition, the technology of fertilization formula and the efficiency of chemical fertilizer.

MethodsClassical statistics method is used to evaluate the abundance of medium and trace element contents in tobacoo leaves of research areas, combined with GPS, using the semivariogram of geostatistics for analyzing of the spatial variability of elements in tobacco leaves, and the spatial distribution patterns of elements are examined using Kriging.

Results1) The means of element contents in tobacco C₃F leaves from study area are as follows, Ca 20.3 g/kg, Mg 3.7 g/kg, Cu 4.42 mg/kg, Zn 34.85 mg/kg, Fe 229.81 mg/kg, Mn 205.43 mg/kg, Mo 0.25 mg/kg, the ranges of 7 element contents are as follows, 14.7–27.3 g/kg, 1.3–8.0 g/kg, 1.69–8.83 mg/kg, 12.31–56.11 mg/kg, 141.62–339.00 mg/kg, 66.21–426.11 mg/kg, 0.06–0.60 mg/kg. The variance coefficients are from 12.8% to 48.7%, which are in moderate variation, according to the standard for rating medium and trace element content in tobacco leaves. Within the tobacco research area, the suitable range of the content of Ca accounts for 95.2%, the high level of Mn content accounts for 65.1%, low levels of Mg, Cu, Zn, Fe contents account for 26.5%, 55.4%, 32.5% and 20.5% respectively, the suitable level account for 48.2%, 25.3%, 63.9% and 79.5% respectively, while tobacco leaves of research area lacks Mo. 2) Ca, Mg, Zn and Fe contents have normal distribution, and other elements are transformed to have normal distribution, exponential model is the best fitting theoretical semivariogram model for contents of Ca, Cu, Fe and Mo, gaussian model for Mg, Zn and Mn. Anisotropic ratio of Ca, Mg, Cu, Zn, Fe, Mn, Mo are greater than 1 respectively, nugget coefficients are 43.8%, 26.9%, 31.0%, 58.4%, 69.0%, 32.6% and 42.7% respectively, spatial heterogeneity ranges are respectively 148.099, 137.407, 15.554, 18.723, 25.624, 88.770 and 74.749 km.

ConclusionsThe content of Ca is in suitable level, the content of Mn is rich, the contents of Mg, Cu, Zn and Fe are within low to suitable level, while Mo is deficient. Geostatistical analysis shows that contents of 7 elements are spatially anisotropic; spatial variability index-nugget coefficient from large to small is: Fe > Zn > Ca > Mo > Mn > Cu > Mg, 7 elements have middle spatial correlation; spatial autocorrelation range from large to small is followed by Ca, Mg, Mn, Mo, Fe, Zn, Cu. Spatial distribution maps reflect the distribution situation of 7 elements of tobacco leaves in research areas.