BMC Plant Biology最新文献

The soil legacy of successively grown winter wheat (WW) often leads to lower plant growth and yield. In this study, we assessed the effect of Bacillus pumilus seed inoculation on the early growth of successively grown WW. We conducted an outdoor experiment using newly designed temperature-regulated rhizotrons. WW was grown in soil from two rotational positions, i.e., first WW after oilseed rape (W1) and second WW after oilseed rape (W2), until the end of tillering. We measured several plant and soil biochemical parameters. In addition, amplicons of the 16S rRNA gene were sequenced to account for bacterial and archaeal community shifts in the rhizosphere, and functional genes involved in the nitrogen cycle were quantified to estimate possible changes in N cycling due to B. pumilus inoculation. B. pumilus seed coating significantly compensated for the early growth reduction of W2, and this effect was primarily linked to changes in root plasticity with a higher root length density and a smaller specific root length in inoculated W2 compared with non-inoculated W2. There was a higher LAP activity in the rhizosphere of inoculated W2 plants than in the rhizosphere of non-inoculated W2 plants and this was followed by a reduction in soil NO₃^-, most probably due to an enhanced plant N uptake capacity. This was also shown in the increased potassium content of the inoculated W2 plants compared with their non-inoculated counterparts. B. pumilus seed coating did not influence the bacterial and archaeal alpha and beta diversity, but differential abundance analysis identified differences in the relative abundance of certain taxa between non-inoculated and inoculated W2. While B. pumilus seed coating significantly improved root growth and nutrient uptake in W2, this was not accompanied by a higher absolute abundance of bacterial or archaeal genes involved in N-cycling. Our study suggests that certain plant-beneficial microbes can reverse the negative plant-soil feedback in successive WW rotations and provides strong evidence of B. pumilus seed coating to promote WW productivity under such rotations.

Background: To investigate the state transition processes of plant community in desert steppe under different stocking rates, this study aims to systematically uncover the intrinsic characteristics of such transition processes and their underlying network-driven mechanisms across three hierarchical levels (i.e., species, functional group, and plant family). The findings are expected to provide a robust scientific basis for optimizing adaptive grassland management strategies and facilitating the restoration of degraded desert steppe ecosystems.

Methods: The study was conducted in Stipa breviflora desert steppe. Four grazing treatments were established: control (CK, no grazing), light grazing (LG), moderate grazing (MG), and heavy grazing (HG), with stocking rates of 0, 0.91, 1.82, and 2.71 sheep units·hm⁻²·half year⁻¹, respectively. Plant population height, coverage, and density were surveyed, and importance values were calculated. Based on species composition proportion and resource allocation proportion matrices, a Bray-Curtis state transition model was constructed.

Results: The CK treatment exhibited the highest community self-stability. Species composition stability increased with increasing stocking rates (across the LG-HG gradient), while resource allocation stability decreased with increasing stocking rates below MG (CK > LG > MG). Grazing disturbance made grassland degradation easier than recovery. Restoring degraded grasslands requires a stepwise reduction grazing strategy: "from HG to MG to LG". State transitions across stocking rates occurred at multiple levels. Population proportion similarity showed bipolar differentiation, while resource dependence on grazing conditions exhibited a three-dimensional response. Perennial grasses (PG) showed significant resource output tendencies, perennial forbs (PF) acted as the core receiving center, and shrubs/semi-shrubs (SS) and annual/biennial plants (AB) served as intermediaries. Poaceae (POA) dominated resource output, while Asteraceae (AST) and Chenopodiaceae (CHE) functioned as key transfer hubs.

Conclusion: In summary, multiple stable states formed by grazing in desert steppe. The differentiation in species response strategies and reallocation among functional groups/families are the core mechanisms driving state transitions. For degraded grasslands, promoting recovery through stepwise reduce stocking rate is superior to fencing exclusion.

Scots pine (Pinus sylvestris L.) is widely distributed, phenotypically plastic forest tree species with modest ecological demands, therefore it is a very suitable, drought tolerant species for afforestation at present. This is especially important given Europe's changing climate, with rising extremes and unpredictable rainfall challenging forest regeneration. Drought resistance of seedlings is essential for their survival during current reforestation efforts, however, its relation to ecotypic variation is yet not well understood. The objective of this study was to investigate the response of seedlings from two Czech Scots pine ecotypes (upland and lowland), exposed to water deficit at the beginning of the vegetative season - a critical period for successful afforestation from the perspective of precipitation availability. During a greenhouse experiment with nursery pre-grown seedlings, terminal shoot length and selected leaf functional traits (leaf mass per area; water and pigment contents; needle anatomy), chlorophyll fluorescence kinetics and seedling reflectance were monitored during ten-week irrigation reduction and after rewatering. The photochemical reflectance index (PRI) and the red edge position (REP) were calculated from spectral reflectance to distinguish differently treated seedlings. The lowland ecotype grew faster under control but suffered stronger growth reduction and higher mortality under drought. In contrast, across all recorded responses, the upland ecotype responds more consistently to changes in water availability, does not reduce terminal growth, accumulates less biomass and exhibits lower mortality. In general, for terminal growth, there was a significant effect of treatment and also an interaction of treatment and ecotype during the recovery period, unlike the drought period. REP was responsive in recovery period for upland ecotype while PRI showed no consistent drought-related pattern. Our results, in agreement with the fluorescence-based indicators, suggest that current-year needles are more suitable for drought stress detection using spectral indices. The upland ecotype showed several functional traits corresponding to better resilience to drought stress compared to the lowland ecotype. Understanding drought stress and recovery responses via effective leaf functional traits will help forest management to select suitable ecotypes for reforestation, ensuring a higher survival under changing climatic conditions.