Liu Haoqiang, Li Hongjun, Peng Zhuchun, Li Sichen, Ran Chun
Citrus Research Institute, Southwest University, Beipei District, Chongqing 400715, China.
National Engineering Research Center for Citrus, Chinese Academy of Agricultural Sciences, Beipei District, Chongqing 400712, China.
Plants (Basel). 2025 Jul 2;14(13):2024. doi: 10.3390/plants14132024.
Citrus is one of the most widely consumed fruits in the world, and its cultivation industry continues to develop rapidly. However, the roles of soil protistan communities during citrus growth are not yet fully understood, despite the potential significance of these communities to the health and quality of citrus. In this study, we examined the soil properties and protistan communities in Eureka lemon farmlands located in Chongqing, China, during the flowering and fruiting stages of cultivation, both in greenhouse and open-field settings. In general, the majority of the measured soil properties (including nutrients and enzyme activities) exhibited higher values in open-field farmlands in comparison to those observed in greenhouse counterparts. According to the results of high-throughput sequencing based on the V9 region of eukaryotic 18S rRNA gene, the diversity of soil protistan communities was also higher in open-field farmlands, and both lemon growth stage and cultivation modes showed significant effects on soil protistan compositions. The transition from traditional agricultural practices to greenhouse farming resulted in a significant transformation of the soil protistan community. This transformation manifested as a shift towards a state characterized by diminished nutrient cycling capabilities. This decline was evidenced by an increase in phototrophs (Archaeplastida) and a concomitant decrease in consumers (Stramenopiles and Alveolata). Community assembly analysis revealed deterministic processes that controlled the succession of soil protistan communities in lemon farmlands. It has been established that environmental associations have the capacity to recognize nitrogen in soils, thereby providing a deterministic selection process for protistan community assembly. Furthermore, a production index was calculated based on 12 quality parameters of lemons, and the results indicated that lemons from greenhouse farms exhibited a lower quality compared to those from open fields. The structure equation model revealed a direct correlation between the quality of lemons and the cultivation methods employed, as well as the composition of soil protists. The present study offers insights into the mechanisms underlying the correlations between the soil protistan community and lemon quality in response to changes in the cultivation modes.
柑橘是世界上消费最为广泛的水果之一，其种植业持续快速发展。然而，尽管土壤原生生物群落对柑橘的健康和品质具有潜在重要性，但在柑橘生长过程中这些群落所起的作用尚未得到充分了解。在本研究中，我们考察了位于中国重庆的尤力克柠檬果园在栽培的开花和结果阶段，温室和露天环境下的土壤性质及原生生物群落。总体而言，与温室果园相比，大多数测定的土壤性质（包括养分和酶活性）在露天果园中表现出更高的值。根据基于真核生物18S rRNA基因V9区域的高通量测序结果，露天果园中土壤原生生物群落的多样性也更高，并且柠檬生长阶段和栽培模式对土壤原生生物组成均有显著影响。从传统农业做法向温室种植的转变导致了土壤原生生物群落的显著变化。这种变化表现为向养分循环能力减弱状态的转变。光合生物（古质体生物）增加，而消费者（不等鞭毛类和囊泡虫类）相应减少，证明了这种下降。群落构建分析揭示了控制柠檬果园土壤原生生物群落演替的确定性过程。已经确定环境关联有能力识别土壤中的氮，从而为原生生物群落构建提供确定性选择过程。此外，基于柠檬的12个品质参数计算了生产指数，结果表明温室果园的柠檬品质低于露天果园。结构方程模型揭示了柠檬品质与所采用的栽培方法以及土壤原生生物组成之间的直接相关性。本研究为响应栽培模式变化时土壤原生生物群落与柠檬品质之间相关性的潜在机制提供了见解。
