ABSTRACT
To examine the effects of different cultivation history (5 a,10 a, and 15 a) on soil microbial communities, we used Illumina sequencing to investigate the diversity and structure of soil bacterial and fungal communities from Torreya grandis 'Merrillii' fields. The results showed that bacterial Shannon index, the richness estimators Chao1 and ACE were lower in soil in 15 year-old stand than those in other cultivation histories, while Simpson index showed no significant variation. Results from bacterial community NMDS showed that cultivation history played a vital role in driving the changes of soil bacteria communitiy structure. The bacterial communities in 5 and 10 year-old stand had the similar composition. The variations of bacterial richness and diversity as well as community structure (comprised basically of Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi) were significantly correlated with soil organic matters, soil C/N, and total nitrogen. The fungi richness estimators of Chao1 and ACE were significantly decreased with increasing cultivation history. Shannon and Simpson indices were significantly higher in soil with 10 year-old stand than soils with other cultivation history. Fungal NMDS could be clustered in the same era. Fungal communities were comprosed of Ascomycota, Basidiomycota and Zygomycota. Changes in fungal richness/diversity and community structure were mainly controlled by the variation of soil organic matter. In conclusion, the predominant factors affecting soil microbial communities were the cultivation history, soil C/N, total nitrogen and organic matter, respectively.
Subject(s)
Biodiversity , Soil Microbiology , Taxaceae/growth & development , Agriculture , Bacteria , SoilABSTRACT
Photosynthetic characteristics of strawberry (Fragaria ananassa Duch cv. 'Toyonoka') leaves grown in either elevated CO(2) (700 microL/L) or ambient CO(2) (390 microL/L), and at three levels of nitrogen nutrition (12 mmol/L, 4 mmol/L, 0.4 mmol/L) were studied. The results showed that for strawberry grown in 12 mmol/L nitrogen, P(n), maximal carboxylation rate (V(c, max)), maximal linear electron flow through photosystem II (J(max)), electron flow to the photosynthetic carbon reduction cycle (J(c)) and q(P) were all significantly higher in plants grown and measured at elevated CO(2) than for plants grown and measured at ambient CO(2) (Table 1 and 2, Fig. 2), which were due to a significant increase in J(c) exceeding any suppression of electron flow to the photorespiratory carbon oxidation cycle (J(o)). This increase in photochemistrical quenching with decreased non-photochemistrical quenching (q(N) or NPQ) at elevated CO(2) alleviated photoinhibition by high light (Table 2, Fig. 3). For plants grown at 4 mmol/L and 0.4 mmol/L nitrogen, P(n), V(c, max), J(c) and q(P) were all significantly lower in plants grown and measured at elevated CO(2) than for plants grown and measured at ambient CO(2) (Table 1 and 2, Fig. 2). Consistent with decreased photochemistrical quenching and increased non-photochemistrical quenching (q(N) or NPQ), for leaves grown at 4 mmol/L and 0.4 mmol/L nitrogen, the photoinhibition was aggravated by elevated CO(2) (Table 2, Fig. 3). Elevated CO(2) suppressed J(o) in leaves of plants grown at 12 mmol/L, 4 mmol/L and 0.4 mmol/L nitrogen (Fig. 2). The results above suggested that deficient nitrogen (4 mmol/L and 0.4 mmol/L nitrogen) and elevated CO(2) result in an acclimatory decrease of photosynthesis in leaves of plant grown in elevated CO(2).
