Aims

Studies dealing with plants’ mineral nutrient status under elevated atmospheric CO₂ concentration (eCO₂) are usually conducted in closed hydroponic systems, in which nutrient solutions are entirely renewed every several days. Here, we investigated the contribution of the fluctuation of concentrations of N ([N]), P ([P]), and K ([K]) in nutrient solutions in this short period on their concentrations in cucumber plants exposed to different [CO₂] and N levels.

Methods

Cucumber (Cucumis sativus L.) plants were hydroponically grown under two [CO₂] and three N levels. [N], [P], and [K] in nutrient solutions and cucumber plants were analyzed.

Results

The transpiration rate (Tr) was significantly inhibited by eCO₂, whereas Tr per plant was increased due to the larger leaf area. Elevated [CO₂] significantly decreased [N] in low N nutrient solutions, which imposed an additional decrease in [N] in plants. [P] in nutrient solutions fluctuated slightly, so the change of [P] in plants might be attributed to the dilution effect and the demand change under eCO₂. [K] in moderate and high N nutrient solutions were significantly decreased, which exacerbated the [K] decrease in plants under eCO₂.

Conclusions

The short-term fluctuation of [N] and [K] in nutrient solutions is caused by the asynchronous uptakes of N, K, and water under eCO₂, which has an appreciable influence on [N] and [K] in plants besides the dilution effect. This defect of the closed hydroponic system may let us exaggerate the negative impact of eCO₂ itself on [N] and [K] in plants.

中文翻译：

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封闭的水培实验设施中矿质元素浓度的短期波动是否会影响暴露于CO 2升高的黄瓜植株中的矿物质浓度？

目的

通常在封闭的水培系统中进行有关大气CO ₂浓度升高（eCO ₂）下植物矿物质营养状况的研究，其中每隔几天就更新一次营养液。在这里，我们调查了在短期内营养液中N（[N]），P（[P]）和K（[K]）浓度波动对暴露于不同水分胁迫下的黄瓜植物中浓度的贡献。 CO ₂ ]和N水平。

方法

黄瓜（Cucumis sativus L.）植物在两个[CO ₂ ]和三个氮水平下水耕生长。分析了营养液和黄瓜植株中的[N]，[P]和[K]。

结果

蒸腾速率（Tr）被eCO ₂显着抑制，而单株Tr由于叶面积更大而增加。在低氮营养液中，升高的[CO ₂ ]会显着降低[N]，从而使植物中的[N]进一步降低。营养液中的[P]略有波动，因此植物中[P]的变化可能归因于稀释效应和eCO ₂下需求的变化。在中等和高氮养分溶液中的[K]显着降低，这加剧了在eCO ₂下植物的[K]降低。

结论

营养液中[N]和[K]的短期波动是由eCO ₂下N，K和水的异步吸收引起的，除了对植物的[N]和[K]产生显着影响外，[N]和[K]的影响也很大。稀释作用。封闭水培系统的这种缺陷可能会让我们夸大eCO ₂本身对植物中[N]和[K]的负面影响。