Nitrogen-Use Efficiency among Flue-Cured Tobacco Genotypes
- V. A. Sisson ,
- T. W. Rufty and
- R. E. Williamson
Today's flue-cured tobacco (Nicotiana tabacum L.) cultivars differ significantly in yield and quality from cultivars grown early in the 20th century. One major change in crop management has been an increase in fertilizer use, especially N. In view of the changing fertilization practices and the current importance of N in crop production, this study was initiated to evaluate genetic variability in N-use efficiency in flue-cured tobacco. Twelve popular cultivars spanning a period of development from the 1920s through the 1980s were evaluated at fertilizer N rates of 47, 68, and 89 kg ha-1 in 1986, 1987, and 1988 at the Upper Piedmont Research Station, Reidsville, NC. Measures of cured-leaf yield and total N concentration in leaves were used to determine N-use efficiency and its component parts, N-uptake efficiency and N-utilization efficiency. Significant differences were found among cultivars and among N rates for all traits. Modern cultivars were higher yielding at all N fertility levels. Values for N-use efficiency increased from the oldest to the newest cultivars. Variation in N-use efficiency among the cultivars tested was due to increases in both N-uptake efficiency and the efficiency of utilization of accumulated N in the production of dry matter. Nitrogen-use efficiency of all cultivars examined decreased as the level of applied N increased. Nitrogen-use efficiency was positively correlated with chemical quality of the cured leaf. Breeding for improved yield and quality of flue-cured tobacco cultivars has indirectly led to improvements in N-use efficiency.
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