A preview of perennial grain agriculture: knowledge gain from biotic interactions in natural and agricultural ecosystems

Abstract

Abstract. Compared to their annual analogues, perennial grain cropping systems provide various beneficial attributes for the environment and ecosystem services related to resource use efficiency, soil erosion, and soil conservation. However, there is only limited understanding of the multiple biotic interactions in perennial cropping systems and their potential effects on the crop, involving plant growth-promoting and pathogenic microorganisms, beneficial and detrimental faunal organisms below-and above-ground, weeds, and overall biodiversity effects. We use information from studies carried out in managed and natural perennial systems of analogous structure such as perennial energy crop production systems and grasslands to highlight and specify biotic interactions and processes, which potentially constitute advantages and constraints in developing perennial grain cropping systems. Concerning the relevance of soil microorganisms and potential perennial crop breeding goals, we focus on a range of plant-microbe interactions in the rhizosphere involved in biofertilization, phytostimulation, and biological control of soil pathogens. We consider relationships within the faunal community emphasizing arthropod pests and their natural enemies, as well as crop-weed interactions. Based on these outcomes and in comparison with annual systems, we discuss and compile benefits, options, and limitations of management of crop-associated biotic interactions and biodiversity, which might contribute to reproducible and sustainable effects of perennial grain crop productivity. We conclude that management strategies for perennial grain cropping systems depend much more on ecological processes and interactions operating in natural ecosystems than those in annual cropping systems. Consequently, the use of agrochemicals for pest, weed, and disease control, as well as the use of synthetic fertilizers, counteracts the principle functions of the system and would strongly degrade the potential of biotic benefits. We also found that there is only vague information on the long-term productivity and cultivation period of perennial grain crops, the specific management operations of replacement, and the potential development and management of weed and pest populations. Overall, an advanced understanding of interactions between the crop and its biotic environment provides the opportunity to manipulate specific functional traits of crop-associated organisms for improved management and crop productivity, but significant research challenges for implementation of perennial grain crops still remain.

Analysis of infection with fungi of the genus Fusarium seed and vegetative organs of crops

“…Fungi F. verticillioides and F. graminearum can persist in the soil and plant residues for up to three years, for example, slowly decomposing parts of a corn plant can be the reserves of infection for many years. [21,25]. Viable conidia are easily brown by wind, water droplets, infection from plant residues plays a much greater role in the development of the disease than inoculum, introduced by different ways of transmission of infection.…”

Is the future of agriculture perennial? Imperatives and opportunities to reinvent agriculture by shifting from annual monocultures to perennial polycultures

“…Mycorrhizal fungi are a noteworthy category of soil organisms that are clearly affected by ecosystem conversion to agriculture [50]. Mycorrhizae form symbiotic relationships with most species of plants, and are often important, if not essential, for increasing nutrient availability, suppressing plant diseases, and building SOM [35].…”

Integrating multipurpose perennial grains crops in Western European farming systems

“…Compared to annual grains, the larger and more persistent root system of perennial grains can have a positive impact on soil health with positive effect on soil porosity, aggregate stability, water infiltration, nutrient cycles and microbial activity (Crews et al, 2016;Crews and Brookes, 2014;Culman et al, 2010;DuPont et al, 2014;Rasche et al, 2017). Water quality can also be improved by transitioning from annual to perennial grain production in sensitive watershed areas.…”

“…However, the periodic use of a perennial phase in the crop rotation will likely improve soil carbon in the long term (Franzluebbers et al, 2014;King and Blesh, 2018), suggesting larger soil carbon gains than carbon losses to the atmosphere during the conversion back to annuals (Grandy and Robertson, 2007). Finally, the assumed increase of root exudation should enable beneficial processes related to soil-plant interactions (e.g., microbial biofertilization or phytostimulation, in Rasche et al, 2017). Within a short time frame (over one or two years), microbial changes are likely to be some of the most visible changes in soil due to perennial roots.…”