Positive effects of elevated CO₂ and its interaction with nitrogen on safflower physiology and growth
2013
Mohamed, Shiren J. | Jellings, Anita J. | Fuller, Michael P.
Over the last two decades, the impact of elevated CO₂ on crops has become a major issue in the context of climate change. Increasing CO₂ levels should modify the plant demand for nutrients, but precise effects on plant physiology are poorly known. Here, we studied the effect of ambient CO₂ at 400 μmol mol⁻¹ and high CO₂ at 1,000 μmol mol⁻¹ on safflower (Carthamus tinctorius L.) at N levels from 25 to 175 kg ha⁻¹. Growth and physiology of safflower were assessed in pots in controlled enclosure chambers in a glasshouse. Overall results show that high CO₂ increased assimilation rate by +27 %, leaf area index (LAI) by +28 %, total above-ground dry weight by +51 %, and total above-ground dry weight by +43 % at harvest. High CO₂ reduced stomatal conductance by −29 % and transpiration rate by −18 %. At anthesis, results show that high CO₂ increases assimilation rate by +13 %, LAI by +2 %, and above-ground dry weight by +34 %. At anthesis, results also show that high CO₂ decreases leaf N and chlorophyll content.
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