Aims

Gypsum soils are P-limited atypical soils that harbour a rich endemic flora. These singular soils are usually found in drylands, where plant activity and soil nutrient availability are seasonal. No previous studies have analysed the seasonality of P nutrition and its interaction with the arbuscular mycorrhiza fungi (AMF) colonisation in gypsum plants. Our aim was to evaluate the seasonal changes in plant nutrient status, AMF colonisation and rhizospheric soil nutrient availability in gypsum specialist and generalist species.

Methods

We evaluated seasonal variation in the proportion of root length colonised by AMF structures (hyphae, vesicules and arbuscules), plant nutrient status (leaf C, N and P and fine root C and N) and rhizospheric soil content (P, organic matter, nitrate and ammonium) of three gypsum specialists and two generalists throughout a year.

Results

All species showed arbuscules within roots, including species of Caryophyllaceae and Brassicaceae. Root colonisation by arbuscules (AC) was higher in spring than in other seasons, when plants showed high leaf P-requirements. Higher AC was decoupled from inorganic N and P availability in rhizospheric soil, and foliar nutrient content. Generalists showed higher AC than specialists, but only in spring.

Conclusions

Seasonality was found in AMF colonisation, rhizospheric soil content and plant nutrient status. The mutualism between plants and AMF was highest in spring, when P-requirements are higher for plants, especially in generalists. However, AMF decoupled from plant demands in autumn, when nutrient availability increases in rhizospheric soil.

中文翻译：

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生长在贫磷土壤中的石膏专家和普通物种的 AMF 定植、土壤和植物养分含量的季节性变化

宗旨

石膏土壤是含磷限制的非典型土壤，具有丰富的地方性植物群。这些单一的土壤通常存在于旱地，那里的植物活动和土壤养分可用性是季节性的。以前没有研究分析磷营养的季节性及其与石膏植物中丛枝菌根真菌 (AMF) 定植的相互作用。我们的目的是评估石膏专家和通才物种的植物养分状况、AMF 定植和根际土壤养分有效性的季节性变化。

方法

我们评估了 AMF 结构（菌丝、囊泡和丛枝）、植物营养状况（叶 C、N 和 P 以及细根 C 和 N）和根际土壤含量（P、有机质、硝酸盐）定植的根长比例的季节性变化。和铵）三个石膏专家和两个通才全年。

结果

所有物种都显示根内有丛枝，包括石竹科和十字花科的物种。当植物表现出高叶磷需求时，丛枝 (AC) 的根定植在春季高于其他季节。较高的 AC 与根际土壤中无机氮和磷的有效性以及叶面养分含量脱钩。通才表现出比专科医生更高的 AC，但仅限于春季。

结论

在 AMF 定植、根际土壤含量和植物营养状况中发现了季节性。植物和 AMF 之间的共生在春季最高，此时植物的 P 要求更高，尤其是在通才中。然而，当根际土壤中养分有效性增加时，AMF 在秋季与植物需求脱钩。