Agronomic Practices Affecting Nicotine Concentration in Flue‐Cured Tobacco: A Review

Abstract

Proposed regulations mandating lower nicotine concentrations in tobacco (Nicotiana tabacum L.) products will likely require changes in tobacco production to reduce nicotine while maintaining yield and quality. The agronomic practices used for tobacco production have a significant impact on the synthesis and accumulation of nicotine in flue‐cured tobacco. Nicotine is the primary alkaloid in flue‐cured tobacco and is one of the main reasons for its commercial production. Most agronomic practices that improve plant health and yield have a positive effect on nicotine production and accumulation. Some of the most important factors that affect nicotine concentrations are N fertilization, planting density, topping practices, sucker control, and harvesting practices. The amount of N available to the plant has a substantial effect on nicotine, as N is a primary component of the nicotine molecule. Factors leading to higher N uptake lead to higher nicotine concentrations. Plant and leaf densities within the field also have a significant effect on nicotine, where increasing densities leads to lower nicotine concentrations. Flowering and sucker production are both significant sinks of energy and other resources. Eliminating the inflorescence via topping and controlling suckers lead to higher nicotine concentrations. In fact, substantial nicotine synthesis and accumulation occurs in the days and weeks following topping. This comprehensive review discusses the agronomic factors affecting alkaloid production in flue‐cured tobacco, and how these factors can be adjusted to manipulate the ultimate nicotine concentration. Core Ideas Proposed regulations may require lower tobacco nicotine concentrations. Production practices and timing significantly influence nicotine and leaf quality. Nitrogen fertility, crop density, growth regulation, and harvesting are paramount. Low density, high N, and increased maturity enhance nicotine accumulation. Flowers and axillary shoots are sinks that limit foliar nicotine concentrations.

Genetics influence postharvest measurements of flue‐cured tobacco more than nitrogen application rate

“…All rights reserved. Cavlek, 2006;Parker, 2009;Henry et al, 2019); therefore, our results were not unexpected with the conventional genotypes NC95 and K326. However, it is interesting to note that the same pattern was not observed in the low alkaloid genotypes.…”

“…It is well established that N application and tobacco alkaloid accumulation are positively correlated (Cavlek et al, 2006;Felipe & Long, 1988;Flower, 1999;Henry et al, 2019;Ismail & Long, 1980;McCants & Woltz, 1967;Parker, 2009;Peedin, 1999;Weybrew et al, 1983;Woltz et al, 1949); therefore, our results were not unexpected with the conventional genotypes NC95 and K326. However, it is interesting to note that the same pattern was not observed in the low-alkaloid genotypes.…”

“…Their final concentration in cured leaves is thus directly related to N application rate (Bush, 1999; Tso, 1990). In addition, tobacco leaf senescence is directly related to N assimilation from the soil profile and subsequent metabolism within the plant (Henry et al., 2019; Peedin, 1999; Weybrew et al., 1983). It is therefore plausible that reduced N rates might alleviate the late‐ripening issues associated with low alkaloid genotypes.…”

Flue-cured tobacco tolerance to S-metolachlor

“…The decline in total alkaloid concentration is likely a result of vegetative dilution since yield was simultaneously improved in the 1× rate (Table 5). In general, factors that improve cured leaf yield will likewise reduce total alkaloid concentration as a result of increased biomass and root growth (Henry et al 2019). Cured leaf quality and reducing sugar concentration were not influenced by application rate in this environment.…”

Measures of Canopy Structure from Low-Cost UAS for Monitoring Crop Nutrient Status

“…These nutrients perform crucial roles in plant development and are needed in relatively high concentrations at specific plant growth stages [8]. Nutrient toxicity is also important to monitor for many crops, such as boron (B) in flue-cured tobacco, which has negative effects on leaf quality due to increased nicotine and other alkaloids [9][10][11]. Remote monitoring of crop nutrient status with UAS can provide on-demand, fine-grained spatial information to improve crop productivity and minimize over-application of fertilizers if integrated into existing precision agriculture technology used on-board commercial tractors and implements.…”