Production of very low nicotine Burley tobacco: short term feasibility from an agronomy viewpoint
The U.S. Food and Drug Administration (FDA) has issued an Advance Notice of Proposed Rulemaking (ANPRM) to obtain information for developing a product standard that would lower nicotine to non-addictive levels. They have requested comments on a maximum limit of around 0.3-0.5 mg/g. We do not believe that this limit is technically feasible on a nationwide scale in the short term with the varieties currently available. Nicotine levels are extremely variable between crops. We examined data collected over decades in the Minimum Standards Program, focusing on the two checks. Nicotine levels were mostly 35-55 mg/g, but they were as high as 72 mg/g, and as low as 18 mg/g. These data are weighted means for the whole plant; the leaf grade, which comprises most of the weight, is at least 12-15 % higher. LA (low alkaloid) mutants reduce nicotine to about 10 % of the wild type: 3.5-5.5 mg/g in the average crop, which is still tenfold higher than the limit in question. Agronomic practices can reduce nicotine further, but results are notoriously variable. Data we have collected over the years show: a) not topping reduced nicotine to 55-60 % of topped tobacco, b) close spacing reduced it to 65-95 % of standard spaced tobacco, c) drastically reducing nitrogen fertilizer reduced it to 40-94 % of standard fertilized tobacco, d) early harvesting reduced it to 64-78 % of standard harvested tobacco. We know that irrigation reduces nicotine, but we do not have any data. We are currently testing the combined effect of all these factors. We do not yet have any data, but it is unlikely that it will reduce nicotine to below 10 % of standard-grown tobacco, and even more unlikely that it will do so consistently. Several groups are working on molecular nicotine reduction. It is possible that they will achieve the 0.3-0.5 mg/g nicotine levels, but it could be years before such varieties are available to growers on a commercial scale, if the industry maintains its current testing procedures.