Oil crops are the second most cultivated economic crop in the world after food crops, and they are an important source of both edible and industrial oil. The growth of oil crops is limited by biotic and abiotic stresses, which hinder their yield and quality. Among all the agronomic measures, plant growth promoting bacteria (PGPB) play a crucial role in improving the yield, quality, and adaptability of oil crops. In this review, we considered the recent research on the sources of beneficial bacteria and their interactions with and influences on host plants, with a focus on summarizing the important roles and molecular mechanisms of PGPB in promoting growth and resisting biotic and abiotic stresses in oil crops. Finally, we outlined the current opportunities and challenges of microbial strategies for the improvement of the yield, quality, and adaptability of oil crops, providing a theoretical basis for the future use of microbial inoculants in these crops.
Abstract Dryland soils consistently exhibit a low capacity for the long‐term accumulation and storage of organic matter, which has been primarily attributed to low plant biomass inputs under drought suppression. Whether, and how, soil organic matter (SOM) compositions contribute to the consistently low SOM storage have been puzzling. A fundamental understanding of this mechanism is particularly essential to achieve the aspiration of ‘4 per mille Soils for Food Security and Climate’. By screening the molecular composition of dissolved organic matter (DOM), the gatekeeper of SOM decomposition, we explored the transformation processes among the pools of SOM, DOM and microbial biomass carbon (MBC) in soils along a precipitation gradient on dryland grasslands of the Tibetan Plateau. The results revealed that the number and mean weight of DOM molecules significantly decreased, and the soil DOM composition gradually shifted to be more labile along the transition from meadow, steppe, to desert with decreasing precipitation, coinciding with the substantial reduction in SOM. Compared with meadow soils, DOM degradability increased by 8.7% in steppe soils and by 23.4% in desert soils. The ratio of soil MBC to total organic carbon was threefold higher in desert than in meadow, and positively correlated with DOM degradability, indicating that labile DOM accelerated microbial growth and SOM decomposition in desert soils. Structural equation model and correlation analyses demonstrated that the DOM degradability was primarily controlled by soil dissolved nitrogen and soil organic C and soil DOC/DN ratio. Synthesis and application . This study at a molecular level provides a novel insight into the important role of the degradability of dissolved organic matter in carbon accumulation in dryland soils with consistently low organic matter storage. The findings will inform better global managements of soil organic matter under consideration of both food security and climate change.
The role of soil decomposer animals in nutrient cycling is commonly seen as indirect, slow and cumulative, through grazing and engineering effects on soil microbes and their mineralization activities. Here, we show that nitrogen (N) and carbon (C) movement from living soil animals to plants and herbivores can be extremely rapid. In two complementary experiments under laboratory and field conditions, we used stable isotope tracers to follow nutrient transfer from earthworms to soil, wheat seedlings, and aphids. Earthworm-derived 15N and 13C was acquired by aphids after 2 h under laboratory conditions, and 15N after 24 h in the field. Since cleansed earthworms with voided guts were introduced, the main source of this 15N and 13C likely was their highly labelled cutaneous mucus. Based on the rapid tracer appearance in a phloem-feeding herbivore (whose principal N source is free amino acids), we postulate that organic earthworm-excreted compounds, possibly amino acids and acetates, may have been involved. This would suggest a previously unknown shortcut in the terrestrial N and C cycle, however, it requires confirmation through advanced techniques such as compound-specific isotope analysis or liquid chromatography with mass spectrometry. These experimental results suggest that multitrophic linkages from living decomposers in soil to plants and aboveground consumers may happen at much shorter time scales than is generally assumed.
Degraded farmlands have been abandoned worldwide, especially in high- and middle-income countries. These lands help combat climate change as they undergo natural recovery of vegetation and soil carbon and remove carbon dioxide from the atmosphere. However, recovery can be slow, requiring decades to centuries to approach pre-cultivation or natural states, and in some cases, soils remain degraded without active restoration. In this perspective, we present an overview of how carbon capture and storage on abandoned farmland can be accelerated and maximized via managing plant diversity as both a means and an end of restoration, creating and applying biochar to soil, and co-developing with renewable energy as techno-ecological synergies. These strategies can jointly tackle climate change and land degradation while contributing to and reinforcing multiple other Sustainable Development Goals. Although challenges exist, adoption of these strategies could be facilitated by increasing governmental and corporate initiatives at global and regional levels, especially developing carbon-offset markets for agriculture.
With the rapid development of social economy and urban−rural integration, the phenomenon of farmland abandonment worldwide has proved to be one of the main trends of land use and land cover change (LUCC), and profoundly affected the rural landscape and regional ecological environment. Restricted by the natural environment, economic development and backward agricultural technology, the phenomenon of farmland abandonment is also common in the Qingzang Plateau (QP). Therefore, this paper adopted the spatial autocorrelation method to analyze the spatial pattern of abandonment in the agricultural and pastoral areas of the Qingzang Plateau (APA−QP) in 2017, and the geographically weighted regression (GWR) model to explore the effects of geographical resources, socio-economic development and location conditions on farmland abandonment. This study found that: 1) From 2015 to 2017, the abandoned farmland area in the APA−QP was approximately 18.23 × 104 ha, with an overall abandonment rate of 15.18%. On the whole, it showed the distribution characteristics of "strong in the south and weak in the north, strong in the east and weak in the west". 2) There were positive spatial correlation between both abandoned area and abandonment rate in the APA−QP, showing "concave" and "convex" patterns, respectively, mainly concentrated in the Huang−shui Valley and the Southeast Tibet; while in the western and northern regions, the degree of abandonment was relatively low. 3) Farmland abandonment in the APA−QP was mainly driven by the geographical environment changes and farmers' decision−making on farmland utilization. There was significant spatial heterogeneity on farmland abandonment associated with the impact of geographical resources, socio−economics and location conditions. The geographical resource factors had a positive impact on the abandonment, and were strongly constrained by natural geographic conditions such as altitude and slope. The farmland resources in the Qingzang Plateau are limited, but are of strategic significance for the sustainable development of agriculture in the whole Qingzang Plateau. In order to realize the rational distribution of agriculture and animal husbandry and the sustainable utilization of farmland resources in the plateau region, land use strategies should be implemented according to regional differences and regional advantages in order to ensure the ecological environment security of Qingzang Plateau.
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