Purpose

Rising atmospheric CO₂ levels associated with climate change increase plant nutrient demands. However, few studies have examined the interactions of atmospheric CO₂ and P supply on root exudation which plays a crucial role in mobilising non-labile P in soil. This study aimed to examine the interactive effects of elevated CO₂ and P deficiency on root exudation of organic acid anions and sugars over time.

Methods

White lupin (Lupinus albus L.) was grown at 1, 5 and 50 µM P in solution culture under ambient (380 ppm) and elevated (700 ppm) CO₂ levels. Root exudates were collected after 3, 4, 5 and 6 weeks of treatment, and organic acid anions and sugars were quantified using liquid chromatography-mass spectrometry.

Results

Elevated CO₂ and P deficiency positively interacted to enhance citrate exudation between 3 and 5 weeks of growth, while malate was only sporadically affected by elevated CO₂ and fumarate remained unaffected. Elevated CO₂ also increased exudation of glucose and fructose with larger increases being observed in P-deficient plants, which was largely constrained after 4 weeks. Elevated CO₂ had no effect on exudation rates as plants matured.

Conclusion

The positive interaction between CO₂ and P deficiency led to increases in organic acid anion and sugar exudation, indicating that rising atmospheric CO₂ levels could allow plants to access greater amounts of non-labile P when faced with P deficiency thereby reducing their reliance on non-renewable fertiliser inputs.

中文翻译：

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升高的CO 2和磷缺乏交互地增强了羽扇豆的根系渗出。

目的

与气候变化有关的大气中CO ₂含量上升，增加了植物对养分的需求。但是，很少有研究检查大气中CO ₂和P供给对根系渗出的相互作用，这在动员土壤中不稳定的P方面起着至关重要的作用。这项研究旨在研究随着时间的推移，CO ₂和P缺乏症升高对根系中有机酸阴离子和糖的渗出的相互作用。

方法

白羽扇豆（Lupinus albus L.）在环境（380 ppm）和升高（700 ppm）CO ₂浓度的溶液培养中分别以1、5和50 µM P生长。处理3、4、5和6周后收集根分泌物，并使用液相色谱-质谱法对有机酸阴离子和糖分进行定量。

结果

在生长的3到5周之间，升高的CO ₂和P缺乏正向相互作用，以增强柠檬酸盐​​的渗出，而苹果酸仅偶尔受到升高的CO _2的影响，而富马酸盐则不受影响。升高的CO ₂也会增加葡萄糖和果糖的渗出，在缺磷的植物中观察到更大的增加，这在4周后受到很大的限制。随着植物的成熟，升高的CO ₂对渗出速率没有影响。

结论

CO ₂和P缺乏症之间的正向相互作用导致有机酸阴离子和糖的渗出增加，表明大气中CO ₂含量的升高可能使植物在面临P缺乏症时能够获取更多的非不稳定P，从而减少了对非P的依赖-可再生肥料投入。