The Effect of Management Practices on Grade Distribution in Flue-cured Tobacco

Edwards, Patrick Boddie. The Effect of Management Practices on Grade Distribution in Flue-Cured Tobacco. (Under the direction of W. David Smith.) Two studies were conducted in 2002, 2003, and 2004. The first study was conducted at eleven locations and evaluated the effect of certain management practices on tip grade production in flue-cured tobacco. Treatments included six varieties, a normal nitrogen rate or normal plus 22 kg/ha of nitrogen, a normal or high topping height, and four versus five harvests. Four harvests involved keeping the last ten to twelve leaves together while five harvests split the ten to twelve leaves into two groups. The nitrogen rate treatment was only used in 2002 and was replaced with the topping height variable in 2003 and 2004. The variety NC 606 was added only in 2004. The second study was conducted at one location in 2003 and one in 2004 and investigated the effect of lower-leaf removal on the yield, quality, and grade distribution of flue-cured tobacco. Six treatments were included in the test in which the two controls involved no lower-leaf removal but were harvested three or four times. The other four treatments included a combination of removing the bottom four or eight leaves and harvesting the remainder of the leaves either two or three times. In the tip grade production study, the most consistent factor affecting tip grades was cured-leaf color. Harvesting five times consistently produced more tip grades than harvesting four times in all three years of research. In 2002, a higher nitrogen rate reduced tip grades when it contributed to unripe tobacco. In 2003 and 2004, older varieties such as Speight G 28 and McNair 944 produced more tip-graded tobacco than the newer varieties K 326 and NC 71. High topping resulted in more tip grades in two of three locations in 2003 and one of four locations in 2004. In all three years of the study, an immature and/or unripe grade of tobacco was less likely to receive a tip grade regardless of treatment applied. Riper grades that were more likely to receive a tip grade included F, FR, K, and N1BO which are based on the USDA grading system. Cultivars K 326 and NC 71 produced higher yield and values per hectare than Speight G 28 and McNair 944 at nearly all test locations. Also, Speight G 28 and McNair 944 tended to receive lower average prices per kilogram than K 326 and NC 71. In general, varieties McNair 944 and Speight G 28 and the management practice of five harvests resulted in the highest proportion of tip graded tobacco because the treatment resulted in ripe grades that were dark in color such as FR and K. Although Speight G 28 and McNair 944 received a higher percentage of tip grades, these varieties are not a good varietal choice for production due to low yields and disease resistance. For the lower-leaf removal research conducted in 2003 and 2004, the most significant decreases in yield and value per hectare occurred when eight leaves were removed, regardless of the harvest method. Removing four leaves had a minimal impact on yield and value. No significant differences were observed in grade distribution in either year of lowerleaf removal research. THE EFFECT OF MANAGEMENT PRACTICES ON GRADE DISTRIBUTION IN FLUE-CURED TOBACCO