[Illumina Miseq sequencing-based fungal community of rhizosphere soils along root orders of poplar plantation]. / åŸºäºŽé«˜é€šé‡æµ‹åºçš„æ¨æ ‘äººå·¥æž—æ ¹é™ åœŸå£¤çœŸèŒç¾¤è½ç»“æž„.

The study on microbial community composition in rhizosphere soils surrounding different order roots is of great significance for understanding the interactions between roots and microbes. Using Illumina Miseq sequencing technology, this study analyzed the differences of fungal community structure in bulk soils and rhizosphere soils surrounding different root orders of poplar (Populus × euramericana 'Neva') tree. The microbial species annotation showed that 128, 124, 130 and 101 fungal genera were classified in the rhizosphere soils around 1-2 order roots (R1), 3 order roots (R2), 4-5 order roots (R3) and in the bulk soils (NR), respectively. The differences of present fungal genera indicated a selectivity mechanism driving fungal community assembly in poplar rhizosphere soils. There were seven fungal genera with more than 1% of relative abundance in rhizosphere soils. Trichoderma was the dominant fungal genus in R1. Trichosporon and Aspergillus were the dominant fungal genera in R2 and R3, respectively. Alpha (α) diversity indices showed that the fungal diversity was significantly different among root orders. Specifically, the diversity of soil fungal community in the rhizosphere soils around lower order roots was significantly higher than that of higher order roots (P＜0.05). Beta (ß) diversity indices showed that the dissimilarity of fungal community composition increased along with the root orders. All these results implied the different composition and structure of fungal community are closely related with the function of fine root orders.

[Seasonal dynamics of quantitative and morphological traits of poplar fine roots and their differences between successive rotation plantations].

Based on the fine root samples of the first and second generations of poplar (Populus x euramericana ' Neva'), this study examined the response of quantitative and morphological traits of fine roots of different orders and the difference between generations. The results showed that, the quantitative traits of fine roots, such as root length, root surface area and root biomass, presented obvious seasonal variation, and the fine root traits had obvious difference among root orders. The quantitative traits of lower-order fine roots showed significant seasonal difference, and the fine root biomass increased in the growing season and then decreased significantly. The specific root length (SRL) of higher-order roots also showed significant change with season, while the root length density (RLD) and root tissue density (RTD) changed a little. The successive rotation resulted in the significant increase of root length, root biomass, SRL and RLD of 1-2 orders in the growing season. The quantitative traits of first order root significantly positively correlated with soil temperature and moisture, and significantly negatively correlated with the soil organic matter and soil available nitrogen content. However, the quantitative traits of second order root only showed significant correlation with soil nutrient content. The seasonal dynamics of poplar fine roots and the difference between successive rotation plantations implied carbon investment change of poplar to roots. Soil nutrient deficiency induced more carbon investment into roots, and this carbon allocation pattern might affect the aboveground productivity of poplar plantation.