Background: P deficiency in karst areas significantly influenced leaf photosynthesis and carbon metabolisms in plants which were bad for plant growth. Meanwhile, fertilizer application would cause lots of environmental problems. Therefore planning and developing P deficiency-resistant plants in karst areas are important to prevent shortage of P resources and reduce the environmental impacts of P supplementation.
Results: This study examined the photosynthetic response of three climber plant species, namely, Pharbitis nil (Linn.) Choisy, Lonicera pampaninii Levl, and Parthenocissus tricuspidata (Sieb. et Zucc.) Planch to phosphorus (P) deficiency stress. The plants were exposed to P deficiency stress at three treatments of 0.125 mM, 0.031 mM, and 0 mM for 30 d; 0.250 mM P was used as the control. Photosynthetic responses were determined by measurement of leaf photosynthesis, chlorophyll fluorescence, carbonic anhydrase activity, and stable carbon isotope ratios. Pharbitis nil showed high CA activity, more negative delta C-13 values and could maintain long-term stable photosynthetic capacity. Lonicera pampaninii also showed high CA activity but positive d13C values compared to Pharbitis nil, and its photosynthetic capacity decreased as P deficiency stress increased. Parthenocissus tricuspidata had a low photosynthesis and positive d13C values compared to Pharbitis nil, it could grow normally even under 0 mM P.
Conclusions: Pharbitis nil was tolerant to long-term, severe P deficiency stress, a finding that is attributed to its stable PSII and regulation of carbonic anhydrase. Lonicera pampaninii showed a poor adaptability to short-term P deficiency, but exhibited long-term tolerance under 0.125 mM P concentration. Parthenocissus tricuspidata was tolerant to long-term P deficiency stress, may exhibit a stomatal limitation. Besides, P deficiency stress had little effect on the way of inorganic carbon utilization of the three climber plants. Different adaptation mechanisms to P deficiency stress should be considered for the selection of species when developing P deficiency-resistant plants.
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