<abstract xmlns="http://www.w3.org/1999/xhtml">A field experiment was carried out in 1996 in Central Italy in order to evaluate the effects of nitrogen fertilization (0, 60, 120 kg h-1 N) of Virginia tobacco (cv. K394) in terms of net assimilation, growth and yield. Measurements of net leaf assimilation of CO2 were taken at midday under conditions of strong sunlight (<italic>Anhigh</italic>) using a portable infra-red gas analyzer and at decreasing photosynthetic photon flux density by shading the leaves with filters (<italic>An vs PPFD</italic>). For <italic>An vs PPFD</italic> measurements the <italic>Anmax</italic> value was calculated as the asymptote of the function proposed by CONNOR et al. (1). Growth was analysed by taking weekly samples to determine the fresh and dry weight and LAI (Leaf Area Index).Before topping, <italic>Anhigh</italic> (average assimilation found in lower, middle and upper leaves) rose in proportion to increased levels of N (14.7, 17.2, 20.2 μmolm-2 s-1, for 0, 60 and 120 kg ha-1 N respectively). After topping, <italic>Anhigh</italic> also grew with increased levels of N, but at a lower rate (6.8, 7.2 and 8.2μmol m-2 s-1, respectively).Similarly, for each of the three fertilization methods (N0, N60 and N120) the increase in <italic>Anmax</italic> in relation to N levels was greater before topping than afterwards (i.e. 18.7, 23.3, 26.3 μmolm-2 s-1 before topping compared to 7.5, 14.0 and 17.8 μmol m-2 s-1 after topping for each treatment respectively). The decrease of CO2 assimilation after topping was probably caused by the accumulation of soluble photo assimilates in the leaf which could have led to a feed-back control on leaf photosynthesis. In N60 and N120 treatments, which had the same leaf expansion rate of 0.14 m2 m-2 d-1 (m2 of leaf on m2 of soil per day), the rapid leaf expansion phase started about 40 days after transplanting, while it started some days later in N0 (rate of 0.11 m2 m-2 d-1). That phase ended at topping in N60 and N120, while in N0 it ended some days before topping. Biomass accumulation followed the same pattern of LAI. The rapid biomass accumulation phase was characterised by growth rates of 9, 16 and 19 g d.m. m-2 d-1, respectively for the N0, N60 and N120 treatments but did not end at topping. This confirms that assimilate accumulation occurred after topping but was not accompanied by leaf expansion. At fertilization rates of 0, 60 and 120 kg N ha-1 the yields of cured leaf tobacco were 3226, 4202 and 4839 kg ha-1 respectively.</abstract>

A field experiment was carried out in 1996 in Central Italy in order to evaluate the effects of nitrogen fertilization (0, 60, 120 kg h-1 N) of Virginia tobacco (cv. K394) in terms of net assimilation, growth and yield. Measurements of net leaf assimilation of CO2 were taken at midday under conditions of strong sunlight (Anhigh) using a portable infra-red gas analyzer and at decreasing photosynthetic photon flux density by shading the leaves with filters (An vs PPFD). For An vs PPFD measurements the Anmax value was calculated as the asymptote of the function proposed by CONNOR et al. (1). Growth was analysed by taking weekly samples to determine the fresh and dry weight and LAI (Leaf Area Index).Before topping, Anhigh (average assimilation found in lower, middle and upper leaves) rose in proportion to increased levels of N (14.7, 17.2, 20.2 μmolm-2 s-1, for 0, 60 and 120 kg ha-1 N respectively). After topping, Anhigh also grew with increased levels of N, but at a lower rate (6.8, 7.2 and 8.2μmol m-2 s-1, respectively).Similarly, for each of the three fertilization methods (N0, N60 and N120) the increase in Anmax in relation to N levels was greater before topping than afterwards (i.e. 18.7, 23.3, 26.3 μmolm-2 s-1 before topping compared to 7.5, 14.0 and 17.8 μmol m-2 s-1 after topping for each treatment respectively). The decrease of CO2 assimilation after topping was probably caused by the accumulation of soluble photo assimilates in the leaf which could have led to a feed-back control on leaf photosynthesis. In N60 and N120 treatments, which had the same leaf expansion rate of 0.14 m2 m-2 d-1 (m2 of leaf on m2 of soil per day), the rapid leaf expansion phase started about 40 days after transplanting, while it started some days later in N0 (rate of 0.11 m2 m-2 d-1). That phase ended at topping in N60 and N120, while in N0 it ended some days before topping. Biomass accumulation followed the same pattern of LAI. The rapid biomass accumulation phase was characterised by growth rates of 9, 16 and 19 g d.m. m-2 d-1, respectively for the N0, N60 and N120 treatments but did not end at topping. This confirms that assimilate accumulation occurred after topping but was not accompanied by leaf expansion. At fertilization rates of 0, 60 and 120 kg N ha-1 the yields of cured leaf tobacco were 3226, 4202 and 4839 kg ha-1 respectively.

Effect of Nitrogen Fertilization on the Photosynthetic Activity, Growth and Yield of Virginia Tobacco (Nicotianatabacum L.)

Dipartimento di Arboricoltura e ProtezionedellePiante, Perugia, Italy

Contributions to Tobacco & Nicotine Research

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

A field experiment was carried out in 1996 in Central Italy in order to evaluate the effects of nitrogen fertilization (0, 60, 120 kg h-1 N) of Virginia...

Effect of Nitrogen Fertilization on the Photosynthetic Activity, Growth and Yield of Virginia Tobacco (Nicotianatabacum L.)

Publié en ligne: 06 janv. 2015

Pages: 245 - 254

Reçu: 22 janv. 1999

Accepté: 10 oct. 1999

DOI: https://doi.org/10.2478/cttr-2013-0688

© 1999 Beiträge zur Tabakforschung International

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.