Artikel,
Photosynthesis and growth responses of mustard (Brassica juncea L. cv Pusa Bold) plants to free air carbon dioxide enrichment (FACE)
PROTOPLASMA, (Juli 2015)
DOI: \%7B10.1007/s00709-014-0723-z\%7D
Zusammenfassung
Increased atmospheric CO2 is likely to affect photosynthesis, plant growth, and yield potential of plants. Mustard (Brassica juncea L.) is an important oil seed crop that is widely grown in India. Therefore, the impact of elevated CO2 (585 mu mol mol(-1)) on pigment and protein content, chlorophyll a fluorescence, photosynthetic electron transport reactions, CO2 assimilation, biomass production, and seed yield potential was measured in B. juncea cv Pusa Bold, grown inside free air carbon dioxide enrichment (FACE) rings installed on the campus of Jawaharlal Nehru University, New Delhi, India. Plants were grown for three consecutive winter seasons (2010-2013), in ambient (385 mu mol mol(-1)) or elevated CO2, in field conditions. Elevated CO2 had no significant effect on the minimal chlorophyll fluorescence (F (0)), while the quantum efficiency of Photosystem II, measured as variable fluorescence (F (v) = F (m)-F (0)) to maximum fluoresence (F (m)), increased by 3 \%. Electron transport rate, photosystem I, photosystem II, and whole chain electron transport rates increased by 8 \% in elevated CO2. However, the net photosynthesis rate increased by a parts per thousand 50 \% in three growing seasons under elevated CO2 condition. The stomatal conductance and transpiration rate decreased resulting in higher photosynthetic water use efficiency. The photosynthesizing surface, i.e., leaf area index substantially increased leading to higher biomass and seed yield under elevated CO2 condition. Acclimatory downregulation of photosynthesis and plant productivity was not observed in three consecutive growing years suggesting that in the absence of nutrient limitation, B. juncea is highly responsive to elevated CO2 whose yield potential shall increase in changing climatic conditions.
