Tobacco Crops Research Articles

Impact Assessment of Bidi Tobacco in Gujarat

Tobacco, the golden leaf is one of the important high value commercial crops grown in over 15 states in India. It is a highly remunerative crop fetching more economic benefits to the farmers. Among different types of tobacco, bidi tobacco is an important non-FCV tobacco grown largely in Gujarat. The present study was conducted in the year 2019 with an objective to assess the impact of tobacco crop on socio-economic transformation of tobacco farmers in Gujarat state. The total sample size of the study was 160. The average net returns from bidi tobacco were Rs. 65000/ha. in Gujarat compared to wheat (Rs. 25,000/ ha) and jowar (Rs. 15000/ha). The socio-economic impact was high for tobacco growers in terms of land size, annual income, expenditure pattern, possession of assets, net returns, habitat &educational security and social empowerment than non-tobacco farmers. The major constraints identified from tobacco farmers wereprice fluctuation, non-availability of labour, suckers problem and storage facilities. The different factors for growing tobacco were high profit, availability of timely and sufficient credit, location suitability and timely availability of inputs. For non-tobacco crops, the major factors for cultivation were location suitability, adoption of improved technology, quick payment to the produce and government support.

Response of Nitrogen and Sulphur for maximizing the production of Mustard (Brassica juncea) in Rainfed condition of Sub Agro Climatic zone – VI

A field experiment was undertaken at Bidi Tobacco Research Station, Anand Agricultural University, Anand for three consecutive years viz., 2017-18 to 2019-20 to study influence of nitrogen and topping levels on yield and quality of bidi tobacco hybrid varieties. The experiment was laid out in factorial randomized block design assigning two hybrid varieties, i.e. MRGTH 1 and GABTH 2, three nitrogen levels i.e. 140, 180 and 220 kg/ha and three topping levels, i.e. 18, 21 and 24 leaf stages with three replications. The data pooled over three years revealed that tobacco variety GABTH 2 recorded significantly the highest tobacco cured leaf yield (3700 kg/ha) with maximum net realization of `117433/ha and BCR value 3.06. Both the upper levels of 180 and 220 kg nitrogen/ha, being at par with each other produced significantly higher cured leaf yield of 3388 and 3407 kg/ha, respectively as compared to lower level of 140 kg nitrogen/ha. Topping levels were failed to exert their significant effect on tobacco cured leaf yield. Application of nitrogen @ 180 kg/ha gave maximum net realization of `102741/ha and BCR value of 2.81 as compared to lower level of 140 kg/ha whereas, tobacco crop topped at 21 leaves gave maximum net income of `105898/ha with 2.86 BCR. Tobacco varieties and nitrogen as well as topping levels had non-significant effect on leaf chemical constituents i.e. nicotine, reducing sugar and chloride contents. Wherein, only nicotine content was significantly changed due to tobacco varieties and different topping levels. Tobacco variety MRGTH 1 and topping level at 18 leaves gave significantly the highest nicotine content compared to others.

Influence of Nitrogen and Topping Levels on Yield and Quality of Bidi Tobacco Hybrid Varieties

A field experiment was undertaken at Bidi Tobacco Research Station, Anand Agricultural University, Anand for three consecutive years viz., 2017-18 to 2019-20 to study influence of nitrogen and topping levels on yield and quality of bidi tobacco hybrid varieties. The experiment was laid out in factorial randomized block design assigning two hybrid varieties, i.e. MRGTH 1 and GABTH 2, three nitrogen levels i.e. 140, 180 and 220 kg/ha and three topping levels, i.e. 18, 21 and 24 leaf stages with three replications. The data pooled over three years revealed that tobacco variety GABTH 2 recorded significantly the highest tobacco cured leaf yield (3700 kg/ha) with maximum net realization of `117433/ha and BCR value 3.06. Both the upper levels of 180 and 220 kg nitrogen/ha, being at par with each other produced significantly higher cured leaf yield of 3388 and 3407 kg/ha, respectively as compared to lower level of 140 kg nitrogen/ha. Topping levels were failed to exert their significant effect on tobacco cured leaf yield. Application of nitrogen @ 180 kg/ha gave maximum net realization of `102741/ha and BCR value of 2.81 as compared to lower level of 140 kg/ha whereas, tobacco crop topped at 21 leaves gave maximum net income of `105898/ha with 2.86 BCR. Tobacco varieties and nitrogen as well as topping levels had non-significant effect on leaf chemical constituents i.e. nicotine, reducing sugar and chloride contents. Wherein, only nicotine content was significantly changed due to tobacco varieties and different topping levels. Tobacco variety MRGTH 1 and topping level at 18 leaves gave significantly the highest nicotine content compared to others.

𝘚𝘰𝘳𝘨𝘩𝘶𝘮 𝘴𝘶𝘥𝘢𝘯𝘦𝘯𝘴𝘦 AS COVER CROP AND BIOLOGICAL PRODUCTS ON INCIDENCE OF 𝘚𝘤𝘭𝘦𝘳𝘰𝘵𝘪𝘯𝘪𝘢 𝘴𝘤𝘭𝘦𝘳𝘰𝘵𝘪𝘰𝘳𝘶𝘮 AND YIELD OF TOBACCO

Brazil is the world's second largest producer of tobacco (Nicotiana tabacum) with part of its production concentrated in Santa Catarina. The incidence of Sclerotinia sclerotiorum in tobacco areas has promoted a decrease in productivity, and control alternatives are needed due to the limited use of agrochemicals for the crop. With the hypothesis that the sudan grass (Sorghum sudanense) and Trichoderma harzianum reduce the attack of S. sclerotiorum in tobacco crops on the coast of Santa Catarina; the objective here was to test the incidence of S. sclerotiorum and the use of sudan grass associated with biological products on tobacco yield. A study with application of straw from sudan grass (SG); SG + Trichoderma harzianum (TH); SG + TH + Melaleuca alternifolia essential oil; SG + TH + Bacillus subtilis Bacillus licheniforimis; and SG + TH + Bacillus subtilis in a conventional system of tobacco were carried out in São João do Sul and Santa Rosa do Sul, Santa Catarina. Results showed that in São João do Sul, there was no difference between the treatments in yield and incidence of S. sclerotiorum. However, in Santa Rosa do Sul, the association of SG + TH, SG + TH + B. subtilis B. licheniforimis, and SG + TH + B. subtilis presented greater yields than others. In both sites, sudan grass and associations promoted a higher financial return compared to control. More studies are requested to elucidate the physiological effect of biological products and sudan grass as a cover crop on tobacco.

Influence of Different Herbicide Based Weed Management Practices on Growth and Yield of Flue Cured Tobacco in Northern Light Soils of Andhra Pradesh, India

Flue cured tobacco requires clean and weed free environment and thereby reduce the competition for nutrients and moisture for achieving quick early season growth. Deploying effective weed management practices play a key role in achieving better yields and quality. Field experiments were conducted at Peddpauram village of West Godavari district (Andhra Pradesh) during (Rabi) seasons of 2018-19 and 2019-20, to study the effect of different herbicide based weed management practices on growth and yield of flue cured Tobacco crop. The experiment was performed as Randomized Block Design with 11 weed management practices replicated thrice. The results recorded on growth parameters, in both the years revealed that six inter cultivations with two manual removal of weeds significantly impacted plant height (113.5 cm and 114.4 cm) and leaf area index (2.63 and 2.83) at 90 DAT over Imazethapyr applied at 0.05 kg a.i ha-1. Number of leaves plant-1 were higher with six inter cultivation and two manual removal of weeds (21.5 and 20.6) over Imazethapyr 0.05 kg a.i ha-1. Inter cultivations and manual weeding resulted in significantly enhancing yield attributes such as leaf thickness (0.143 mm and 0.143 mm for cutters and 0.183 mm and 0.173 for leaf) and lower leaf count (Number of leaves kg-1) (137 and 129) over weedy check. Application of Sulfentrazone 0.03 kg a.i ha-1 was comparable with inter cultivation and manual weeding. Sulfentrazone 0.3 kg a.i ha-1 contributed for significantly higher yield (2302 kg ha-1 and 2424 kg ha-1) over weedy check and comparable with six inter cultivations and two manual weeding operations. The application of pre emergence herbicides like Pendimethalin, Alachlor and Oxyflurfen resulted achieving higher yield levels over the application of post emergence herbicides such as Quiazalofop-p-ethyl, Fenoxaprop ethyl, Carfentrazone ethyl and Imazethapyr during both years of experimentation.

Are Farmers Willing to Substitute Tobacco Cultivation? Evidence From Lichuan City, China.

Tobacco crop substitution is a critical element in implementing comprehensive tobacco control policies. Understanding tobacco farmers' willingness or preferences is imperative to implement policies on tobacco crop substitution. This article assesses tobacco farmers' individual willingness to substitute tobacco cultivation and investigates the factors that influence their willingness in Lichuan City, China. We conducted a face-to-face survey with 280 tobacco farmers in Lichuan City of China to assess their willingness to substitute tobacco cultivation. The binary probit model was used to examine the factors influencing farmers' willingness to substitute tobacco growing. The results show that fewer than one in five tobacco farmers are willing to substitute tobacco growing with other crops. The main reason for their unwillingness is that they thought the comparative income of growing tobacco was higher and more stable. The regression results show that tobacco farmers with higher education levels and more knowledge of tobacco crop substitution are more willing to take up tobacco crop substitution. Tobacco farmers' household income decreased the likelihood of their willingness to replace tobacco cultivation. Farmers who perceived the economic benefits and health benefits of tobacco crop substitution are more likely to substitute tobacco cultivation with other crops. Farmers' willingness to substitute tobacco cultivation is low. Policy interventions are needed to increase farmers' willingness to stop growing tobacco and to replace it with other alternative crops. Few studies have investigated local farmers' willingness to substitute tobacco cultivation in China. We found most tobacco farmers in the Lichuan City of China are unwilling to substitute tobacco growing with other crops. Farmers' low support of tobacco crop substitution is associated with economic factors. Better education and more knowledge of tobacco crop substitution can increase farmers' willingness to substitute tobacco cultivation.

Functional Response and Predation Potential of Carabus elysii Adults against the Terrestrial Slug Agriolimax agrestis.

Simple SummaryAgriolimax agrestis is one of the most important cash crop pests in China, widely affecting tobacco, vegetables, edible mushrooms, and other crops. Not only does it cause direct damage to plants but it also spreads bacteria that are harmful to plants and humans. Currently, the control of A. agrestis relies mainly on chemical agents; however, the heavy application of chemicals often leads to ecological damage. In this study, using Carabus elysii as a natural enemy, the predatory ability of adult C. elysii on A. agrestis was assessed under indoor conditions for the first time. The results show that C. elysii adults have a strong predatory ability on different sizes of slugs, especially juvenile slugs, and the female adults have a better predatory ability than the male adults. In general, C. elysii has strong potential to control A. agrestis and can be used as an effective control measure.Terrestrial slugs are a prominent agricultural pest worldwide. To mitigate the negative effects of chemical pest control, biological control involves the use of natural enemies to reduce the impact of target pests. Numerous insects are natural predators of slugs. This study evaluated potential of the predatory species, Carabus elysii Thomson (Coleoptera: Carabidae) to biologically control the terrestrial slug, Agriolimax agrestis. Laboratory experiments were conducted to investigate the functional response, searching efficiency, and interference effect of female and male C. elysii adults regarding adult, immature, and juvenile A. agrestis individuals. The results show that both female and male ground beetle adults are functionally capable of preying on different sizes of terrestrial slugs. C. elysii exhibited Holling type II functional responses when preying on A. agrestis. The maximum daily prey consumption was 35.5 juveniles, 25.1 immatures, and 17.1 adults for adult females and 26.9 juveniles, 20.3 immatures, and 11.6 adults for adult males. The searching efficiency of female C. elysii adults regarding A. agrestis was always higher than that of male adults for identical ages and densities of A. agrestis. Moreover, the predation of C. elysii on slugs was affected by predator density. The disturbance coefficient of male C. elysii were the highest on adult A. agrestis. The results of this study suggest that female C. elysii exhibit a high potential for the biological control of A. agrestis.

Tobacco curly shoot virus Down-Regulated the Expression of nbe-miR167b-3p to Facilitate Its Infection in Nicotiana benthamiana.

Tobacco curly shoot virus (TbCSV) belongs to the genus Begomovirus of the family Geminiviridae, and causes leaf curling and curly shoot symptoms in tobacco and tomato crops. MicroRNAs (miRNAs) are pivotal modulators of plant development and host-virus interactions. However, the relationship between TbCSV infection and miRNAs accumulation has not been well investigated. The present study was conducted to analyze different expressions of miRNAs in Nicotiana benthamiana in response to the infection of TbCSV via small RNAs sequencing. The results showed that 15 up-regulated miRNAs and 12 down-regulated miRNAs were differentially expressed in TbCSV infected N. benthamiana, and nbe-miR167b-3p was down-regulated. To decipher the relationship between nbe-miR167b-3p expression and the accumulations of TbCSV DNA, pCVA mediation of miRNA overexpression and PVX based short tandem target mimic (STTM) were used in this study. It was found that overexpression of nbe-miR167b-3p attenuated leaf curling symptom of TbCSV and decreased viral DNA accumulation, but suppression of nbe-miR167b-3p expression enhanced the symptoms and accumulation of TbCSV. PRCP, the target gene of nbe-miR167b-3p, was silenced in plants using VIGS and this weakened the viral symptoms and DNA accumulation of TbCSV in the plants. Overall, this study clarified the effect of nbe-miR167b-3p on plant defense during TbCSV infection, and provided a framework to reveal the molecular mechanisms of miRNAs between plants and viruses.

Chitosan induces tomato basal resistance against Phytophthora nicotianae and inhibits pathogen development

Chitosan is a polymer of glucosamine with antimicrobial properties and an elicitor of plant defence responses. In this study, different chitosan concentrations were assessed for impact on the life cycle of Phytophthora nicotianae Breda de Haan, an oomycete pathogen of tomato and tobacco crops. Reduced mycelial growth was observed when chitosan was added to solid media, and this inhibitory activity was amplified with increasing chitosan concentrations from 0.5 g L−1 to 2.5 g L−1. Colony morphology and hyphal diameter were unaffected by the polymer; however, the number of oospores (sexual reproductive structures) was reduced at the lowest chitosan concentration (0.5 g L−1) tested. Mycelia plugs imbibed with 0.5 g L−1 chitosan were prone to increased sporangium formation, but the effect was subdued with higher chitosan concentrations. The length/width ratio of the sporangia did not change in the presence of the polymer. Indirect germination of the sporangia was particularly sensitive to this compound, and 1.5 g L−1 completely abolished this process. The zoospores treated with chitosan formed cysts that did not germinate and were unable to infect tomato plant roots. Chitosan was also found to prime tomato plantlets for P. nicotianae resistance; a foliar application of 0.1 and 1 g L−1 of chitosan 72 h before inoculation induced host resistance, which was concurrent with increased activity of phenylpropanoid pathway markers. The results presented herein show the potential of chitosan as a tool to control P. nicotianae inoculum and increase tomato crop resistance against this pathogen.

Combined analysis of mRNA and miRNA transcriptomes reveals the regulatory mechanism of PVY resistance in tobacco

Potyvirus (viruses in the genus Potyvirus, family Potyviridae, PVY) is one of the most important pathogens in tobacco (Nicotiana tabacum L.) and other main crops, which cause devastating epidemic and significant production losses of crops worldwide. K326 is an important tobacco cultivar worldwide, but it is seriously plagued by PVY. In this study, an ethyl methanesulfonate (EMS) mutant M867 from K326 was developed, which was highly resistant to PVY. To explore the molecular mechanism of M867 resistance to PVY, RNA-seq and small RNA-seq were applied to analyze the differences between K326 and M867 responds to PVY infection. There are a total of 34 differentially expressed miRNAs and 5083 mRNAs were identified between K326 and M867 following PVY infection. GO and KEGG enrichment analysis showed PVY response process was significantly related with photosynthesis, carbon metabolism, and antioxidant activity. Thereafter, the results of hormone determination showed that the IAA level of K326 was almost zero after PVY infection, but M867 maintained a high IAA content. Simultaneously, the contents of JA and SA in M867 showed a substantial increase. M867 auxin-related genes (e.g., AUX1, IAA4, and ARF9) were significantly down-regulated after PVY infection compared to K326, but genes related to various hormones, such as CTK, GA, ABA, JA, and SA, showed significant up-regulation. Redox-related peroxidase, superoxide dismutase, and catalase were significantly up-regulated by PVY infection. Besides, six pairs of significant mRNA-miRNA interactions were found, and these genes may be closely related to PVY-host interactions. Furthermore, our findings revealed that the differences between M867 and K326 in hormones, redox reactions, and energy metabolism changed the molecular pathway of the PVY-host interaction, which led to PVY resistance in M867. These results provide valuable resources for elucidating the molecular mechanism of the tobacco-PVY interaction.

Willingness of tobacco farmers to accept compensation for tobacco crop substitution in Lichuan City, China

ObjectiveThis study, conducted in China, explores tobacco farmers’ willingness to accept (WTA) compensation for tobacco crop substitution.MethodsThe contingent valuation method was used to elicit farmers’ WTA compensation. A face-to-face survey...

Yield Response, Quality Traits, and Nitrogen-Use Efficiency of a Burley Tobacco Crop Grown in Mediterranean Areas (Southern Italy) as Affected by Intensive N Management

Tobacco is an annual cash crop widely cultivated over the world, which generally needs great amounts (N) of nitrogen to achieve the best yield and quality. However, with a view to sustainable and environmentally friendly agriculture, also for this crop, the reduction in N fertilization is a priority, but without negatively affecting the yield and quality of the cured product. Therefore, field experiments were conducted during 2002 and 2003 on light air-cured (Burley) tobacco at three different locations of the Campania region (Southern Italy) where high-quality light air-cured (Burley) tobacco is traditionally cultivated. At each location, the following six N fertilization treatments were compared with four replications (blocks): (i) a not fertilized control (N0); (ii) 50 kg N ha−1 (N50); 90 kg N ha−1 (N90); 130 kg N ha−1 (N130); 170 kg N ha−1 (N170); 210 kg N ha−1 (N210). The yield of cured leaves appeared positively influenced by N fertilization but not at a rate higher than 170 kg ha−1. N fertilization directly influenced nitrates and the total N content of cured leaves at all locations. The greater values of both parameters were reached at N130 or N90, respectively, at Vitulazio (CE), N170 at Bellizzi (SA), and N90 at San Giorgio del Sannio (BN). The fire holding capacity increased with N fertilization up to N170 treatment (12–13 s at CE and BN but just 8 s at SA). L* (brightness) decreased with increasing N fertilization giving cured leaves less bright and opaquer. The a/b ratio (a*, green/red; b*, blue/yellow) increased with N treatments producing cured leaves of dark hazelnut. The best scores were assigned to cured products obtained by plants fertilized with 170 kg N ha−1. N-use efficiencies were negatively influenced by N fertilization. The best NUE and N-uptake efficiency was recorded in 2002 at Vitulazio (CE), in spite of a higher NO3-N before N fertilization than other locations.

Responses of soil microbial community composition and enzyme activities to long-term organic amendments in a continuous tobacco cropping system

Organic amendment may be an effective management practice for alleviating soil degradation in continuous cropping systems. However, few studies focus on the effects of long-term organic amendments on soil microbial community and microbial nutrient status in continuous tobacco fields. Here, an 11-year field experiment was conducted to investigate the effects of organic amendments on plant and soil physiochemical properties, microbial communities, ecoenzymatic stoichiometry, and glomalin-related soil protein (GRSP) accumulation in a continuous tobacco field. Five treatments were applied: CK (no fertilizer); CF (chemical fertilizer only); CFS (chemical fertilizer plus corn straw); CFO (chemical fertilizer plus oilseed residues); CFM (chemical fertilizer plus composted pig manure). Organic amendments increased soil microbial abundances. Application of organic fertilizers significantly reduced gram-positive to gram-negative bacterial ratios, but significantly increased fungi/bacteria ratios, probably because gram-negative bacteria and fungi are the dominant decomposers of increased available nutrients and recalcitrant materials, respectively. Organic amendments significantly enhanced soil enzyme activities, except for the difference in β-1,4-N-acetylglucosaminidase, Leucine aminopeptidase, and polyphenol oxidase (PPO) activities between the CF and CFO. The lowest soil organic carbon (SOC) content in CFS among organic amendments treatments was probably because the positive priming effects of straw and the highest peroxidase and PPO activities increased stable SOC mineralization rates due to the high C:N:P ratio of nutrients input. Microbial activities were limited by carbon, nitrogen, and phosphorus in CFS, while carbon and phosphorus were the limiting factors in CK, CF, CFO, and CFM. Relative to CF, CFO significantly enhanced microbial carbon and phosphorus limitation, whereas CFM significantly decreased microbial carbon limitation. CFM had the highest GRSP content among treatments. Our results demonstrated that combined application of composted pig manure and chemical fertilizers is a consistently effective measure for alleviating soil degradation in continuous tobacco fields.

Water quality variables and emerging environmental contaminant in water for human consumption in Rio Grande do Sul, Brazil

This research aimed to qualify and quantify physical, chemical, microbiological and emerging environmental contaminants, pharmaceuticals and pesticides in spring waters, which are used for human consumption under different land use and occupation conditions. These conditions were: native forests and swine farming, as well as soy and tobacco crops in two consecutive seasons. Due to the microbiological variables and the pH and apparent color, the spring water studied is not potable, as it does not comply with the legislation due to the contribution of the total coliforms found in the native forest springs. Pharmaceuticals and pesticides were found in the land use and occupation conditions under study, which shows that land uses do not interfere with emerging environmental contaminant variables.

The Optimization Of Cellulose Content In Tobacco Stems (Nicotiana tabaccum L.) With Acid Extraction Method And Alkaline Extraction Method

Tobacco stems are the agricultural waste of tobacco crops that have the potential to be utilized. Use of tobacco stems in general, only in the leave of disposal without handling. Tobacco stems have the opportunity as a source of cellulose because they have a relatively high content of cellulose. The use of proper methods also plays an important role in extracting cellulose on tobacco stems. The research aims to determine the efficiency levels of cellulose extract from tobacco stems (Nicotiana tabaccum L.) with acid extraction methods and alkaline extraction. The research used a complete randomized design with a repeated trial of 2 times. The results showed the alkaline method of producing the best results against the rendemen testing parameters, water content, hemicellulose content, cellulose content, lignin content and FTIR spectroscopy. Yield test, moisture content, hemicellulose content, cellulose content and lignin content was at the best in the alkaline extraction with a concentration of 12% the yield of 43.63%; water content of 7.54%; hemicellulose content 14.33%; cellulose content 46.17%; and 2.83% lignin content. FTIR spectroscopy test shows that all treatments have important and specific function groups on cellulose such as – OH, C-H, and-CH2, so that samples were identified of cellulose.

AtMYB12-Expressing Transgenic Tobacco Increases Resistance to Several Phytopathogens and Aphids

Phytopathogens and pests are two major factors that limit the growth of plants. The expression of a flavonoid regulator gene, AtMYB12(AT2G47460), has been reported to increase the endogenous flavonoid content of tobacco and tomato. Previous research has only focused on the regulation mechanism of v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factors under single stress conditions. Here, research showed that AtMYB12 was involved in regulating the resistance of tobacco to multiple biological stresses such as phytopathogens and aphid. We reported that transgenic tobacco carrying AtMYB12 was more resistant to Ralstonia solanacearum when the up-regulated expression of several defense-related markers, such as NbPR1a, NbNOA1, and NbrbohB, was activated, suggesting that the priming defense of a plant may contribute to bacterial disease resistance. The improvement of the resistance of AtMYB12-expressing transgenic tobacco is achieved by promoting the production of ROS, H2O2, and NO. AtMYB12-expressing transgenic tobacco also has resistance to fungal pathogens, such as Colletotrichum nicotianae Averna and Alternaria alternate. The enrichment of flavonols components, such as rutin, which directly inhibit the growth of C. nicotianae and A. alternate, may also contribute to the defense mediated by AtMYB12 over-expression. At the same time, the results also confirm that AtMYB12-expressing transgenic tobacco enhanced plant resistance to aphid-infested (Aphidoidea) pests. These results suggest that the AtMYB12 gene is a good candidate for pest and disease control, with limited resistance costs and enrichment in flavonols, and that AtMYB12 has a potential in the breeding of disease-resistant tobacco crops.

Fractionation of heavy metals in soils cultivated with tobacco in Pinar del Río, Cuba

Knowledge of the presence of heavy metals in soils of agricultural areas is important to prevent their accumulation in cultivated plants. The objective of the present investigation was to evaluate the total concentrations and fractions of heavy metals Cd, Pb, Zn, Fe, Mn, Ni, Cu, Cr and Co in the tobacco-growing area of Pinar del Río, Cuba and their relationship with the physicochemical properties of soil. For the study, 59 samples of three types of soils were collected at 20 cm depth. The pseudo-total concentrations of metals in the soils are low and lower than the prevention values registered for Cuban soils. In general, the heavy metals studied present a high affinity for the most stable fractions of the soil, which means a low risk of transfer to the tobacco crop or accumulation in groundwater. The pseudo-total concentrations of heavy metals were low, below the alert values established for soils in the region. The heavy metals studied were mainly associated with the residual fraction, the second fraction with the highest association with metals was that linked to manganese and iron oxides. The principal component analysis showed that their main source is pedogenetic and that these elements are closely related to cation exchange capacity and calcium content.

Soil potentials to resist continuous cropping obstacle: Three field cases

Continuous cropping has become the most common system in intensive, modern agricultural production; however, obstacles often appear in continuous cropping patterns after a few years of use. There have been several studies about the impacts of continuous cropping on soil microbial, but few about differences between soil experiencing continuous cropping obstacles and those where such obstacles had been resisted. Here, after ten or twenty years of continuous tobacco cropping, we collected soil samples investigating discrepancies in soil property and bacterial community between soils experiencing continuous cropping obstacles and soils where the obstacles were resisted providing insight into preventing and controlling continuous cropping obstacles. Results showed that soil organic matter (SOM), available phosphorus (AP), total nitrogen (TN), nitrate-N (NO3−-N), and bacterial diversity of samples where continuous cropping obstacles had been resisted were significantly higher than those where continuous cropping obstacles were present. Besides, SOM, AP, TN, and Ammonium-N (NH4+-N) considerably affected the bacterial community. Among all variables, NH4+-N explained the largest proportion of bacterial community variation. Molecular ecological networks were used to putatively identify keystone taxa, including Acidobacteria Gp1, Acidobacteria Gp2, Acidobacteria Gp16, and WPS-1_genera_incertae_sedis. Their relative abundance significantly changed between the two conditions. Overall, our results indicate that decreases in soil nutrient content and bacterial diversity, and significant changes in some keystone taxa abundances may be important factors leading to increased soil-borne diseases and reduced tobacco production potential or quality. Thus, during agricultural production, we could regulate the stability of the soil-crop-microbial ecological system via crop rotation, intercropping, or the use of specialized bio-fertilizers and soil conditioners to mitigate continuous cropping obstacles.

Pyrolysis yields of tobacco crop residue as a potential alternative fuel source

This study aims to utilize the tobacco crop residue to generate a high economic value for the energy sector. In general notion, tobacco crop is burned as a conventional fuel at low prices; however, in this research, tobacco crop residue was processed through pyrolysis in the form of pyrolysis products (liquid and solid yields) providing a promising alternative fuel fulfilling the standardized fuel properties. The pyrolysis was conducted at a laboratory-scale real pilot plant experiment at a fixed bed reactor and was operated at temperature of around 350 °C to 650 °C for 2 hours to navigate the most optimum product. Further, the products comprising char (solid yield) and tar (liquid yield) were investigated by measuring their properties, which include heating value, flash point, viscosity, density, and char yields’ morphology. The measurement results indicated that the heating value of tobacco crop residue from pyrolysis process significantly escalated to 300% compared to that of tobacco crop residue before pyrolysis process. Similarly, several tar properties indicated the liquid fuel standard such as kerosene. Additionally, another product in the form of solid yields is proved to be utilized as a smart material besides having a higher heating value over coal, due to the high-quality carbon specifications. However, further processing is encouraged to navigate the possibility of solid yields into activated carbon.

Soil properties characterization for land-use planning and soil management in watersheds under family farming

Environmental monitoring of small, rural watersheds was one of the components of the Natural Resources Management and Rural Poverty Alleviation Program (RS-Rural) in southern Brazil. The purpose of the monitoring was to assess the impact of promoting soil conservation and environment management practices adopted by farmers and funded by the Program. In four small monitored watersheds, in a total of 95 plots representing distinct land use and soil management, surface soil was collected to characterize ground-zero of the Program by determining several soil physical, chemical and microbiological properties. Principal component analysis (PCA) shows soil physical, chemical and biological properties were decisive in defining the agricultural soils in the rural watersheds with family farming. The sensitivity to chemical properties provides an opportunity to improve soil quality if soil management focuses on altering those properties. Soil management practiced by tobacco farmers leads to rapid, intense degradation of some natural soil properties, especially those related to the dynamics of soil organic matter, compared with more conservationist uses (forest, regrowth, and grassland). Thus, soil management must be reoriented to avoid the progress of degradation and recover soil physical and biological quality. Cover crops and by land-abandonment to allow natural vegetation are important management strategies for the degraded soils used for tobacco production, increasing soil organic matter, nutrients and microbial activity and thus allowing further crop production. In conclusion, watersheds with tobacco cropping have soils with lower quality than when under no-tillage grain production, requiring changes in land use and soil management.