Impact of long-term loquat cultivation on rhizosphere soil characteristics and AMF community structure: implications for fertilizer management

The role of arbuscular mycorrhizal fungi (AMF) in assisting the growth of different fruit tree species is well-established, yet the impact of loquat cultivation under long-term human management on the rhizosphere soil characteristics and AMF community structure remains unresolved. To address this knowledge gap, we collected roots and soil samples from 20-year-old loquat in a loquat germplasm resources nursery with consistent water and nutrient conditions including one wild species (YS), three pure species (GXQH, MHH, DWX), and four hybrid species (ZJ90, JT, JTH, ZU7). Our analysis revealed that AMF colonization rates ranged from 40.57% to 65.54%, with Glomus (30.72%) and Paraglomus (29.46%) being the dominant genera across all varieties. Paraglomus dominated in pure species, while Glomus prevailed in wild species. YS exhibited the highest AMF richness than cultivars. Significant variations in soil nutrients and enzyme activities in the rhizosphere among different varieties. Total nitrogen (TN) and total potassium (TK) were significantly negatively correlated with relative abundance of AMF genera, suggesting that nitrogen and potassium may reduce AMF abundance. Mantel test showed that total carbon (TC) and soil organic matter (SOM) were the key factors influencing AMF community composition (P<0.01). These nutrients were positively correlated with dominant AMF genus (0.06, R2 = 0.05) but negatively with rare genus such as Ambispora (-0.08, R2 = 0.24). Overall, these findings confirmed that plant varieties or genotypes drive changes in AMF communities and further demonstrated that long-term nutrient enrichment reduces the diversity of loquat rhizosphere AMF communities. These results support the use of AMF biofertilizers and reducing fertilizer application.

Rhizosphere microbial community construction during the latitudinal spread of the invader Chromolaena odorata

The colonization of alien plants in new habitats is typically facilitated by microorganisms present in the soil environment. However, the diversity and structure of the archaeal, bacterial, and fungal communities in the latitudinal spread of alien plants remain unclear. In this study, the rhizosphere and bulk soil of Chromolaena odorata were collected from five latitudes in Pu' er city, Yunnan Province, followed by amplicon sequencing of the soil archaeal, bacterial, and fungal communities. Alpha and beta diversity results revealed that the richness indices and the structures of the archaeal, bacterial, and fungal communities significantly differed along the latitudinal gradient. Additionally, significant differences were observed in the bacterial Shannon index, as well as in the structures of the bacterial and fungal communities between the rhizosphere and bulk soils. Due to the small spatial scale, trends of latitudinal variation in the archaeal, bacterial, and fungal communities were not pronounced. Total potassium, total phosphorus, available nitrogen, available potassium and total nitrogen were the important driving factors affecting the soil microbial community structure. Compared with those in bulk soil, co-occurrence networks in rhizosphere microbial networks presented lower complexity but greater modularity and positive connections. Among the main functional fungi, arbuscular mycorrhizae and soil saprotrophs were more abundant in the bulk soil. The significant differences in the soil microbes between rhizosphere and bulk soils further underscore the impact of C. odorata invasion on soil environments. The significant differences in the soil microbiota along latitudinal gradients, along with specific driving factors, demonstrate distinct nutrient preferences among archaea, bacteria, and fungi and indicate complex microbial responses to soil nutrient elements following the invasion of C. odorata.

Inoculants of Arbuscular Mycorrhizal Fungi Influence Growth and Biomass of Terminalia arjuna under Amendment and Anamendment Entisol

Entisol soil is hard and compact in nature, rendering it high in bulk density, which influences root penetration adversely and thereby poor plant growth. In this experiment, used seven treatments in different combination in normal soil, were used as growth media for the Terminalia arjuna seedling. T3 (60% entisol) found the best as it gave the highest biomass in the species regardless of arbuscular mycorrhizal fungi (AMF) treatment. AMF treatment enhanced the growth and biomass of plants significantly in all the given treatments. AMF colonization observed a maximum in tertiary roots. T1 (100% entisol soil) exhibited the highest degree of AMF colonization in tertiary roots, resulting in the highest mycorrhiza dependency of plants for this soil. The addition of normal soil to entisol soil was found to decrease the bulk density, resulting in increased root diameter, and T3 plants exhibited the highest biomass and AMF compatibility for T. arjuna species. The T. arjuna plant's growth and biomass responded positively to AMF in all types of treatments. The plant's growth and biomass were highest in the T3 treatment, which had a bulk density of 1.50 g/cm3. In this study, we combined the entisol with mycorrhizal inoculation of the nursery growing medium to promote plant growth and biomass, improve the plant's ability to hold water and absorb nutrients, and lower the entisol's bulk density. The T. arjuna (Roxb) plant responds very favorably to mycorrhiza inoculation in nursery conditions with the entisol growth medium.

Lithology and niche habitat have significant effect on arbuscular mycorrhizal fungal abundance and their interspecific interactions

The chemical properties of bedrock play a crucial role in shaping the communities of soil and root-associated arbuscular mycorrhizal fungi (AMF). We investigate AMF community composition and diversity in bulk soil, rhizosphere soil, and roots in karst and non-karst forests. Chemical properties of bedrock of the calcium oxide (CaO) and ratio of calcium oxide and magnesium oxide (Ca/Mg), soil pH, and exchangeable Ca2+ were higher in karst carbonate rocks compared to non-karst clastic rocks. Conversely, bedrock phosphorus content (P-rock), silicon dioxide (SiO2) content, and tree diversity exhibited an opposing trend. AMF abundance was higher in non-karst clastic rocks than in karst carbonate rocks. Stronger interspecific interactions among AMF taxa occurred in the bulk soil and rhizosphere soil of non-karst clastic rocks compared to karst carbonate rocks. AMF abundance and diversity were higher in rhizosphere soil and roots, attributed to increasing nutrient availability when compared to the bulk soil. A more complex network within AMF taxa was observed in rhizosphere soil and roots compared to bulk soil due to an increase in AMF abundance and diversity in rhizosphere soil and roots. Comparing non-karst clastic rocks, karst carbonate rocks increased soil nitrogen (N) and P levels, which can be attributed to the elevated content of soil Ca2+ and Mg2+ content, facilitated by the high CaO content and Ca/Mg ratio in the bedrock of karst forests. However, the thicker soil layer exhibited higher soil nutrient storage, resulting in greater tree diversity in non-karst forests. These findings suggest that high tree richness may increase root biomass and secretion of root exudates in non-karst regions, thereby enhancing the abundance of AMF and their interspecies interactions. Consequently, the diverse bedrock properties that drive variations in soil properties, nutrients, and plant diversity can impact AMF communities, ultimately promoting plant growth and contributing to vegetation recovery.

Environmental Adaptability and Energy Investment Strategy of Different Cunninghamia lanceolata Clones Based on Leaf Calorific Value and Construction Cost Characteristics

The calorific value and construction cost of leaves reflect the utilization strategy of plants for environmental resources. Their genetic characteristics and leaf functional traits as well as climate change affect the calorific values. This study explores the differences in energy investment strategies and the response characteristics of energy utilization in leaves to climate change among nine clones of Chinese fir (Cunninghamia lanceolata). Considering the objectives, the differences in the energy utilization strategies were analyzed by determining the leaf nutrients, specific leaf area, and leaf calorific value and by calculating the construction cost. The results showed a significant difference in the ash-free calorific value and construction cost of leaves among different Chinese fir clones (p < 0.05). There were also significant differences in leaf carbon (C) content, leaf nitrogen (N) content, specific leaf area, and ash content. The correlation analysis showed that leaves' ash-free calorific value and construction cost were positively correlated with the C content. Principal component analysis (PCA) showed that P2 is inclined to the "fast investment return" energy investment strategy, while L27 is inclined to the "slow investment return" energy investment strategy. Redundancy analysis (RDA) indicates that the monthly average temperature strongly correlates positively with leaf construction cost, N content, and specific leaf area. The monthly average precipitation positively impacts the ash-free calorific value and construction cost of leaves. In conclusion, there are obvious differences in energy investment strategies among different Chinese fir clones. When temperature and precipitation change, Chinese fir leaves can adjust their energy investment to adapt to environmental changes. In the future, attention should be paid to the impact of climate change-related aspects on the growth and development of Chinese fir plantations.