Progress Towards Perennial Grains for Prairies and Plains

Perennial grain crops have been proposed as environmentally sustainable alternatives to annual grain crop systems that currently dominate the world's major breadbaskets. Proponents emphasize the potential of perennial grains to mimic natural systems and thereby reduce soil erosion, nutrient losses, and degradation of soil quality although need for adequate grain yield is also recognized as a prerequisite for success. Here we assess progress since 2005 (16 y) towards development of perennial grain systems with sufficient productivity to be seen as competent alternatives to annual wheat on the prairies and plains of North America and Australia. Based on reports published in refereed journals, we see little evidence that yield of Intermediate Wheatgrass or perennial wheats have improved to the point they are viable alternatives. Slow progress is attributed to lack of minimum grain yield targets for economic viability, lack of designated target regions where perennial grains are most likely to be competitive against annuals, selection methods that focused on components of yield rather than yield per se (i.e. on an area basis), and relatively small R & D investment compared to resources given to genetic and agronomic improvement of major annual grain crops. Given current status, we conclude that perennial grains will require substantial R & D investment and several decades if they are to achieve sufficient yield potential and yield persistence to become more than a niche crop for upscale health food markets in wealthy countries.

Review and analysis of perennial cereal crops at different maturity stages

The article presents an overview of perennial grain crops, gives a comparative characteristic of annual winter wheat and perennial grain crops such as Trititrigia (Trititrigia cziczinii Tsvelev), Thinopyrum intermedium, perennial rye (Secale cereale L) and perennial sorghum (Sorghum x derzhavinii Tzvel.). The study aims to consider the main perennial crops grown in Russia and in the world, to compare their quality indicators, sowing agrotechnical requirements, cultivation conditions, yields, and to justify the choice of perennial crops that meet the needs and climatic conditions of the Rostov region. Presented is the generalized information on the grain quality changes during maturation, ripeness phases of grain crops are considered. Based on the review, the optimal ripeness phases, at which it is advisable to harvest are presented. Literature review showed that in the phase of lactic (мoлoчнaя cпeлocть) and wax maturity (вocкoвaя cпeлocть) wheat grain contains the greatest amount of basic nutrients. It was found that perennial crops have a positive effect on the state of the soil: prevent its erosion and depletion; there is an accumulation of carbon, soil methane CH 4. Comparative characterization of perennial crops with annual crops shows increased protein content - on average 2-3% higher. Also considered are the green mass quality indicators of perennial crops as a source of nutrients in the feed-production technology.

Review and analysis of technologies for harvesting perennial grain crops

In agriculture, according to the data of the statistical collection, the production of grain crops occupies a large part. At the moment, much attention is paid to the study of perennial crops such as Thinopyrum intermedium and Trititrigia cziczinii Tsvelev. These crops help to: slow down soil erosion, protect water resources, and minimize the leaching of nutrients [1,2]. The non-cereal part of the crop is a significant reserve for strengthening the fodder base of animal husbandry, expanding the range of sources of raw materials for the microbiological industry in the production of fodder proteins. The article provides an overview of technologies and equipment for harvesting grain crops, on the basis of which one of the optimal harvesting method for perennial crops is distinguished - stripping. Based on the results of the literature review, the main technologies used for harvesting grain crops were identified: direct and indirect singlephase and two-phase combine harvesting technologies; one-, two- or three-phase non-combine harvesting technologies including the “neveika” method; standing stripping technology. The purpose of this article is to review existing harvesting technologies and equipment, selection of the optimal harvesting technology for perennial crops such as Trititrigia cziczinii Tsvelev and Thinopyrum intermedium.

The Perennial Grain Crop Thinopyrum intermedium (Host) Barkworth & D.R. Dewey (Kernza™) as an Element in Crop Rotations: A Pilot Study on Termination Strategies and Pre-Crop Effects on a Subsequent Root Vegetable

Intermediate wheatgrass (IWG) may benefit soil fertility in crop rotations. To investigate termination strategies, i.e., autumn ploughing (AP), autumn harrowing (AH) and spring harrowing (SH) on a five-year-old IWG stand, a pilot study was performed. After the treatments, beetroots were sown and the IWG plants were counted twice during the beetroot growing season. The number of IWG plants was highest (20) after the SH strategy, intermediate (14) after the AH, and lowest (3) after the conventional termination strategy, AP. After the first plant count, the plots were subject to mechanical weeding in the form of a stale seedbed (i.e., harrowing twice before sowing). At beetroot harvest, the number of IWG plants was low (3 in SH and AH, 0 in AP) and similar between the treatments. The beetroot production was highest after AP and lowest in SH, and intermediary in AH, which showed no difference from AP and SH. At beetroot harvest, the weed biomass did not differ between the termination strategies. The weeds were mainly annuals. There were no differences in soil bulk density between termination strategies. Our results show that shallow soil tillage is enough to terminate IWG, as long as it repeated. We suggest further studies that investigate the dynamics of crop sequences with IWG, and how to benefit from this crop in rotations.

Genetic Architecture and QTL Selection Response For Kernza Perennial Grain Domestication Traits

Perennial grains have the potential to provide food for humans as well as decrease the negative impacts of annual agriculture. Intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®) is a promising perennial grain candidate that The Land Institute has been breeding since 2001. We evaluated four consecutive breeding cycles of IWG from 2016-2020 with each cycle containing approximately 1100 unique genets. Using genotyping-by-sequencing markers, quantitative trait loci (QTL) were mapped for 34 different traits using genome-wide association analysis Combining data across cycles and years, we found 93 marker-trait associations (MTA) for 16 different traits, with each association explaining 0.8-5.2% of the observed phenotypic variance. Across the four cycles, only three QTL showed an FST differentiation > 0.15 with two corresponding to a decrease in floret shattering. Additionally, one marker associated with brittle rachis was 216 bp from an ortholog of the btr2 gene. Power analysis and quantitative genetic theory was used to estimate the effective number of QTL, which ranged from a minimum of 33 up to 558 QTL for individual traits. This study suggests that key agronomic and domestication traits are under polygenic control, and that molecular methods like genomic selection are needed to accelerate domestication and improvement of this new crop.

Comparing the Deep Root Growth and Water Uptake of Intermediate Wheatgrass (Kernza®) to Alfalfa.

AimsWater is the most important yield-limiting factor worldwide and drought is predicted to increase in the future. Perennial crops with more extensive and deep root systems could access deep stored water and build resilience to water shortage. In the context of human nutrition, perennial grain crops are very interesting. However, it is still questionable whether they are effective in using subsoil water. We compared intermediate wheatgrass (Kernza®) Thinopyrum intermedium, a perennial grain crop, to alfalfa Medicago sativa, a perennial forage, for subsoil root growth and water uptake.MethodsUsing TDR sensors, deuterium tracer labelling, minirhizotrons and the Hydrus-1D model we characterised the root distribution and water uptake patterns of these two perennial crops during two cropping seasons under field conditions down to 2.5 m soil depth.ResultsBoth crops grew roots down to 2.0 m depth that were active in water uptake but alfalfa was deeper rooted than intermediate wheatgrass. All experimental methods concluded that alfalfa used more water from below 1.0 m depth than intermediate wheatgrass. However, simulations predicted that intermediate wheatgrass used more than 20 mm of water after anthesis from below 1 m soil depth. Simulations confirmed the advantage of deep roots in accessing deep soil water under drought.ConclusionsIn regions with high groundwater recharge, growing deep-rooted perennial crops have great potential to exploit deep soil water that is often left unused. However, the road to a profitable perennial grain crop is still long and breeding intermediate wheatgrass (Kernza®) cultivars for increased root growth at depth seems to be a worthy investment for the development of more drought tolerant cultivars.

Kernza intermediate wheatgrass (Thinopyrum intermedium) response to a range of vernalization conditions

Expansion of perennial grain and forage Kernza intermediate wheatgrass to temperate regions may be limited by its vernalization requirements. We compared vegetative and reproductive traits of Kernza plants grown in greenhouse under four environmental treatments of temperature and daylength for a 7 week induction period. Percent of plants which flowered and spikes per plant decreased from 83% and 8.2 at 4°C and 10 h to 15% and 0.4 at 26°C and 15 h, respectively. The variability observed suggests that there is potential for selection for reduced vernalization requirements in Kernza populations.

Formation of the microbiota of the rhizosphere of spelt wheat and intermediate wheatgrass and biological activity of podzolized chernozem

Soil microorganisms play a leading role in the formation of the nutrient regime of the soil, which determines the level of future crop harvest. A complex system of soil-plant-microorganisms is formed, with the participation of which the creation and decomposition of organic matter, the circulation of substances in nature, the preservation of fertility and the creation of an optimal level of nutrients supply. The number of amonifiers in the rhizosphere of cereals changes under the influence of the plant species. The smallest number of amonifiers was noted in the rhizosphere of the Zorya Ukraine — 183.3  28,52, in the rhizosphere of Kernza® and Khors — 202,6  68,0 and 202,2  66,4, respectively, which exceeded the spelt indicator by 10,3–10,5 %. There were 47,5–48,0 103 CFU/g soil of nitrifiers in the soil of the fallow, Khors and Kernza®, in the Zorya Ukraine — 46,0 103 CFU/g soil due to higher aeration and low soil moisture. The difference between the data on cellulolytic microorganisms of the spelе rhizosphere and wheatgrass hybrids was 6,8–9,2 %. The biological activity of the soil is one of the most important indicators of its fertility and cultivation. The most informative indicator is the level of СО2 emission, On the variant the fallow is — 0,39 mg / dm2 per hour, in other variants 0,26–0,34 mg/dm2 per hour. Cultivation of spelt without fertilization leads decrease intensity of carbon release in the 1,5. The cultivation of perennial cereal crops allows maintaining this indicator at a higher level. The intensity of fiber decomposition in the soil of fallow and wheat-wheatgrass hybrids was 66–69 %, and with spelt — 58 %. The amonification capacity in the Zarya Ukrainy variant — 7 mg N-NH4/kg of soil, and with wheat-wheatgrass hybrids at the fallow level — 8–9 mg N-NH4/kg of soil. The same trend persisted with ratio to the opposite process — nitrification. The results of microbiological analysis of the soil selected for different grain crops indicate that the root exudates of plants create favorable conditions for the vital activity of microorganisms. Comparison of the state of populations from agricultural areas with the microbiota of the biocenosis indicates the importance of including perennial grain crops in the crop rotation, which will increase the number of microorganisms in the rhizosphere and improve the conditions for the passage of soil-forming processes.