Hernan R. Tejeda, Ramiro Gonzalez, Alejandro Cox

SQM

Santiago, Chile

2011

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Tobacco production in Chile

Objectives of the study

Flue Cured Tobacco Nitrogen Trial – Effects on Yield and Quality Traits.

Burley Tobacco Nitrogen Trial – Effect on Yield and Quality Traits

Summary and Conclusions

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Limited tobacco production area, located in two regions Norte Chico (31° 30’ - 32° 0’ South; 70° 30’ - 71° 30’ West).

Predominant soils: Alfisols and Inceptisols.

Central Valley (34° 0’ – 36° 45’ South; 71° 45’ – 72° 15’ West).

Predominant soil: Alluvial.

Mediterranean climate: rainy winter, dry summer Winter rainfall increases north-south from 250 mm to 800 mm.

Maximum Summer temp > 30 °C. Minimum Summer temp < 12 °C

Relative humidity below 40%.

All crop production under irrigation.

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Tobacco production is part of intensive crop rotation systems that include cereals, legumes, pastures, sugar beet and other crops.

Production of non-tropical fruits, including table and wine grapes, most of them for export markets, are important tobacco competitors for farm soil, irrigation water an other production resources.

High fertilizer nitrogen rates have been successful in achieving top commercial yields in other crops, i.e., corn (> 20 mt grain ha-1), wheat (> 10 mt grain ha-1) .

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Overall objective: to determine maximum Flue Cured and Burley tobacco yield attainable by increasing fertilizer N rates under farming conditions:

High solar radiation (PAR)

Low relative humidity

Low night temperature

Controlled water supply.

To evaluate the effect of high N rates on:

fresh and cured leaf production,

quality leaf traits: color, N content, nicotine, reducing sugar, grading.

To evaluate the use of field instruments and laboratory determinations to assist in predicting tobacco yield and quality.

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Materials and Methods (I)

FLUE CURED N TRIAL BURLEY N TRIAL

LOCATION Chimbarongo, San Fernando Nancagua, San Fernando

PLANTING DATE October 22, 2002 November 8, 2004

PLANT DENSITY 1.15m x 0.45m 19324 pl ha-1 1.15m x 0.45m19324 pl h-1

EXPER. DESIGN RCBD, 7 treatment, 3 replic. RCBD, 7 treatment, 3 replic.

BASE FERTILIZERS TSP 104 kg P2O5 ha-1 SOP 150 kg K2O ha-1

TSP 145 kg P2O5 ha-1 SOP 291 kg K2O ha-1

CROPMANAGMNT & IRRIGATION

Standard practices as by local CCT-BAT company.

Standard practices as by local CCT-BAT company.

TOPPING Manual, 83 Dat, +application of PRIMETM

Manual, 70 Dat, + application of PRIMETM

HARVEST February 27, 2003. 18 to 22 leaves, 4 priming, a wk apart

February 25, 2005. Plant cut above soil.

CURING Grower’s retrofitted barn Grower’s barn

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Materials and Methods (II) Distribution of N Fertilizer Treatments

Total Total

Fertiliz Transplt Fertiliz Transplt

N [1] 20 Dat 34 Dat N [1] 21 Dat 35 Dat 49 Dat

kg ha-1 kg ha-1 kg ha-1 kg ha-1 kg ha-1 kg ha-1 kg ha-1 kg ha-1 kg ha-1

0 0 0 0 0 0 0 0 0

47 47 0 0 70 70 0 0 0

70 47 23 0 140 70 70 0 0

94 47 47 0 210 70 70 70 0

117 47 47 23 280 70 140 70 0

140 47 70 23 350 70 140 70 70

187 47 70 70 420 70 140 140 70[1]: Urea [2] Sodium Nitrate.

Fertilizer N Distribution

Sidedress [2]

Burley Tobacco Trial

Fertilizer N Distribution

Sidedress [2]

FlueCured Tobacco Trial

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Soil and Plant Analysis – Inst. of Agric. Res., La Platina Exp.Sta., Santiago

Soil fertility, one composite sample per replication Leaf samples, one per treatment, composite over 3 replications

Quality Control Laboratory – Compañia Chilena de Tabaco, CCT - BAT

Nicotine Reducing Sugars

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• Leaf Color Reading • Hydro N Tester (HNT) (similar to Spad-2 instrument)

• Measures light reflectance, associated to chlorophyll content

• 7 – 8 readings / leaf (L6 or L7), 1 leaf / plant, 4 plants/ treatment

total 30 readings /treatment and replication.

NO3- Concentration in Leaf Petioles Horiba Kardy portable NO3- Reader

NO3- read in sap of petioles in same 4 leaves cut from plants

after color reading.

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Flue Cured Tobacco fresh leaf response to N rates and predicted response by an exponential model

Exponential Model:

Y = 24374 - (13836)*(0.99416N) 0 < N < 187 R2 = 0.70

- Small (+) difference in R2 between the exponential and the quadratic model.

- The exponential model gives better fit at the zero and maximum N rates.

- A fresh yield increase of 87% over the zero N rate was produced by the maximum N rate (187 kg ha-1) .

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N (kg ha-1)

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Flue Cured tobacco leaf yield and total N% in leaves

-Maximum N rate produced a 55% cured leaf increase over zero N, compared to the 87% increase by fresh leaf.

- Total leaf N% increases linearly with respect to fertilizer N rates.

Leaves Leaf Trait (1) Fertilizer N rate (kg ha-1)

Sampled 0 47 70 94 117 140 187

Cured Yield [kg ha-1] 2542 2924 3422 3732 3684 3730 3949

Fresh Total N [% d.w.] 2.77 3.10 3.41 3.82 4.02 3.89 4.47

(1): Mean of three replications.

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Flue Cured tobacco nicotine and reducing sugar in cured leaves

- Nicotine concentration stayed below 3 %. - Reducing sugar had a slight decrease at higher N rates. - The Reducing Sugar : Nicotine ratio decreases linearly with respect to N rates.

Leaves Leaf Trait (1) Fertilizer N rate (kg ha-1

)

Sampled 0 47 70 94 117 140 187

Cured Nicotine [%] (2) 1.84 2.15 2.53 2.35 2.47 2.75 2.65

Reducing Sugar [%] (2) 22.02 21.56 22.02 22.80 21.56 20.93 19.07

Red.Sugar : Nicotine 11.98 10.01 8.71 9.72 8.72 7.60 7.20

(1): Mean of three replications.

(2): Cured leaves sampled by treatment and priming. Mean nicotine for each N rate

is the weighted average over 4 primings, leaf mass for each prime is the weight factor

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NO3 concentration in Flue Cured tobacco leaf petiole

Regression equation - NO3 plot data

Y = 20.1 + 27.98*N - 0.1739*N*Dat 0 < N < 187

55 < Dat < 112 R2 = 0.726

A steady decline in NO3 concentration over time (Dat) is observed since the first determination at 55 Dat, except for the highest N rates, where NO3 peaks at 62 Dat.

N rates have a strong effect on NO3 concentration. Very low levels of NO3 are present at zero N rate.

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55 62 69 76 83 94 112

Fertlizer N (kg ha-1)

NO3- in petiole (ppm)

Days after transplant (Dat)

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Mean yield of Burley fresh and cured leaves, and percentage of total N in leaves sampled 70 Dat.

Fertilizer Total Leaf Yield

N Leaf N Fresh Cured

kg ha-1

% kg ha-1

kg ha-1

0 1.75 15,121 2,118

70 1.99 18,374 2,441

140 2.85 24,622 3,152

210 3.09 26,530 3,327

280 3.64 28,816 3,644

350 4.00 33,897 3,935

420 4.23 35,169 4,286

Increase (%) 142 133 102

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Effect of fertilizer N on cured Burley leaf yield and total leaf N concentration

Y = 7.58 – (5.93)*(0.99860)N

0 < N < 420 P< 0.001 R2 = 0.92

Y = 6,365 - (4,271) *(0.998336)N 0 < N< 420 P<0.001 R2 = 0.947

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N (kg ha-1)

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N concentration (%) and yield response to N rates follow a similar geometrical pattern represented by the exponential regression model.

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Observed and predicted Burley cured leaf yield as affected by total N% in leaves

Regression equation:

Y = 6,882 – (6,755)*(0.811)N% 1.68 < N% < 4.43

P<0.001 R2 = 0.893

Almost 90% of the observed yield variation of cured leaves can be accounted for by the exponential regression with N% as predictor variable.

Under the experimental or similar conditions N% may provide an early indication of cured leaf yield.

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Total N in leaves 70 dat (%)

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Effect of DAT and N rates on HNT leaf color readings

Y = - 502.3 + 27.21*Dat - 0.16933*Dat2 + 0.009494*Dat*N

55 < Dat < 128 0 < N < 187 kg ha-1

R2 = 0.78

Y = -187.7 + 21.685*Dat – 0.17330*(Dat)2 + 0.005914*(Dat)*(N) 35 < Dat < 103 0 < N < 420 kg ha-1

R2 = 0.90

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55 62 69 76 83 94 105 112 128

N (kg ha-1)

HNT Leaf color

reading

Days after transplant

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BURLEY TOBACCO

The common statistical model is: Y = A + B*Dat – C*(Dat)2 + D*(Dat)*(N) + e The differences are : (a) estimated coefficients, (b) range of the predictor variables.

FLUE CURED TOBACCO

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Commercial Grading of Burley Tobacco Leaves

Cured Burley tobacco leaves were graded grouped by N rate and leaf position at harvest.

A numerical coefficient between 0.00 (no value) and 1.00 (maximum value) represents the grade.

Total yield of graded leaf per N treatment is the sum of the weight of cured leaves at each plant position for the N treatment multiplied by the respective grading coefficient.

Across all N rates, the grading resulted in a parallel down shift of the graded yield response with respect to the no graded response. As the N rate increases, the resulting grading decreases while the yield difference tend to remain within certain limits

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Effect of Commercial Grading on Cured Burley Leaf Response to Fertilizer N Rates

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Grd=1

Grd=0

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Regression equations, using a factor (grd) to separate graded (grd=1) from no graded (grd=0) leaves: Grd=0 Y = 6637 – (4540)*(0.998466)N Grd=1 Y = 6141 – (4540)*(0.998466)N 0<N<420 P < 0.001 • The difference between regression coefficients, D = 6637 – 6141 = 496 , significant at P<0.001 , represents the separation of the 2 response curves. • Equivalent yield reduction due to grading tend to be constant. As yield increases the fraction of low grade leaves decreases.

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The Flue Cured and Burley fertilizer trials demonstrated that tobacco yield can be substantially increased using high N rates, as it is the case with other farm crops in the region. In both trials the slope of the yield response at the highest experimental N rates shows that further yield increases may be obtained using even higher N rates. No negative effects of high N rates were observed on quality traits.

Leaf color, total N %, nicotine and reducing sugar remained within accepted bounds in Flue Cured tobacco

Burley leaf color, total N% and commercial grading were not affected by high N rates.

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Leaf color, measured with Hydro N Tester (HNT) during the growing season, was affected by days after transplant (Dat) and nitrogen N rates (N) for both tobacco types. The shape of both 3-D relations was similar and could be described by the same regression model. Regression equations differed only in the value of regression coefficients and range of predictors (Dat, N). Grading cured Burley leaves resulted in two parallel regression equations for the response to N rates. The estimated vertical difference of 496 kg ha-1 between the curves is significant at P<0.001. The constant differences between response curves could be explained by the fact that at low yields (N rates) a higher fraction of leaves had low grades whereas at higher yields (N rates) a lower fraction of leaves had low grades.

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Thank you !

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