Effects of different nitrogen forms on photosynthetic rate and the chlorophyll fluorescence induction kinetics of flue-cured tobacco |
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Authors: | H. X. Guo W. Q. Liu Y. C. Shi |
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Affiliation: | (1) Department of Agronomy, Henan Agricultural University, Zhengzhou, Henan, 450002, P.R. China |
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Abstract: | Net photosynthetic rate (P N) of tobacco plants grown with NH4-N as the only N source was the lowest all the times, while P N grown only with NO3-N was the greatest until 22nd day, and P N grown with both NO3-N and NH4-N (1 : 1) was the greatest. Maximal photochemical efficiency of photosystem 2 (PS2), Fv/Fm, and actual quantum yield of PS2 under actinic irradiation (ΦPS2) in plants grown with only NH4-N were greatest at early stage and then decreased and were smaller than those of other treatments. Photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP) in the NH4-N plants were the greatest at all times. Hence excessive NH4-N can decrease not only photochemical efficiency but also the efficiency of utilization of photon energy absorbed by pigments for photosynthesis. Therefore, excessive NH4-N is a hindrance to photosynthesis of flue-cured tobacco. On the other hand, tobacco cultured with an appropriate mixture of NO3-N with NH4-N can sufficiently utilize photon energy and increase the efficiency of energy transformation. |
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Keywords: | actual quantum yield of PS2 Nicotiana photochemical and non-photochemical quenching photosystem 2 |
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