Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 93, A5
Influence of the combined action of fertilizers, nutrition spaces and topping, on the yield and quality of Oriental tobacco
Academy of Agricultural and Forestry Sciences, Bucharest, Rumania.
The experiment involved 12 variants, randomized in 4 replications, arranged in multifloor linear blocks design using the sub-divided plots, on an alluvial, sandy-clay soil. The three factors of the experiment had the following graduations:- factor A : a1- untopped(topped - untopped ) a2 - topped-
factor B : b1 - N20P40K40(dose of fertilizer) b2 - N40P80K80-
factor C : c1- 40 x 12 cm c2- 45 x 15 cm c3- 50 x 20 cm (2 plants in the same hole).
When the dose of chemical fertilizer was doubled from N20P40K40 to N40P80K80, no negative consequence was observed on the period of vegetation of cultivar Djebel 292, used in the experiment. The highest percentage of superior class + class I cured tobaccos was recorded for variant 12 (a2b2c3: topped - N40P80K80 - 200,000 plants/ha), with 81.0%, and for superior class only the best variant was 1 (a1b1c1 - untopped - N20P40K40 - 208,333 plants/ha) with 23.7%. Topping increased yield by 166.02 kg/ha compared with no topping. The dose of N40P80K80, compared with N20P40K40, is not justified, as it increases yield by only 4.5%. Reducing the density of plants per hectare to 148,148 plants/ha, reduced yield by 14,2% (-365.45 kg/ha) compared with the standard density of 40 x 12 cm (208,333 plants/ha). The transplantation at 50 x 20 cm, with two plants in the same hole is not justified for cultivar Djebel 292, compared with the spacing of 40 x 12 cm. Topping and larger doses of chemical fertilizers do not degrade the physical-chemical characteristics of the unfermented tobacco. Although a plant with a swivel root, when fertilized at an optimum level, tobacco showed fascicled roots, developed mostly horizontally. Fertilization, tillage and spray irrigation led to the development of roots in the horizon 0-20 cm, and the mass of dried roots ranged from 87,9% (a2b2c3) to 94,6% (a1b1c1). The total mass of the roots ranged from 30,8 g (a1b1c1) and 55,8 g (a1b2c3). Premature topping did not visibly influence the development of the root system. The complex analysis of the experiments with cultivar Djebel 292, leads to recommend fertilization with N20P40K40, for a density of 208,333 plants/ha, leading to an economic optimum: the highest value of the yield per hectare, 77.3% rate of profit and 2165 kg/ha of cured tobacco.
factor B : b1 - N20P40K40(dose of fertilizer) b2 - N40P80K80-
factor C : c1- 40 x 12 cm c2- 45 x 15 cm c3- 50 x 20 cm (2 plants in the same hole).
When the dose of chemical fertilizer was doubled from N20P40K40 to N40P80K80, no negative consequence was observed on the period of vegetation of cultivar Djebel 292, used in the experiment. The highest percentage of superior class + class I cured tobaccos was recorded for variant 12 (a2b2c3: topped - N40P80K80 - 200,000 plants/ha), with 81.0%, and for superior class only the best variant was 1 (a1b1c1 - untopped - N20P40K40 - 208,333 plants/ha) with 23.7%. Topping increased yield by 166.02 kg/ha compared with no topping. The dose of N40P80K80, compared with N20P40K40, is not justified, as it increases yield by only 4.5%. Reducing the density of plants per hectare to 148,148 plants/ha, reduced yield by 14,2% (-365.45 kg/ha) compared with the standard density of 40 x 12 cm (208,333 plants/ha). The transplantation at 50 x 20 cm, with two plants in the same hole is not justified for cultivar Djebel 292, compared with the spacing of 40 x 12 cm. Topping and larger doses of chemical fertilizers do not degrade the physical-chemical characteristics of the unfermented tobacco. Although a plant with a swivel root, when fertilized at an optimum level, tobacco showed fascicled roots, developed mostly horizontally. Fertilization, tillage and spray irrigation led to the development of roots in the horizon 0-20 cm, and the mass of dried roots ranged from 87,9% (a2b2c3) to 94,6% (a1b1c1). The total mass of the roots ranged from 30,8 g (a1b1c1) and 55,8 g (a1b2c3). Premature topping did not visibly influence the development of the root system. The complex analysis of the experiments with cultivar Djebel 292, leads to recommend fertilization with N20P40K40, for a density of 208,333 plants/ha, leading to an economic optimum: the highest value of the yield per hectare, 77.3% rate of profit and 2165 kg/ha of cured tobacco.