Maize stalk stiffness and strength are primarily determined by morphological factors

The maize (Zea mays) stem is a biological structure that must balance both biotic and structural load bearing duties. These competing requirements are particularly relevant in the design of new bioenergy crops. Although increased stem digestibility is typically associated with a lower structural strength and higher propensity for lodging, with the right balance between structural and biological activities it may be possible to design crops that are high-yielding and have digestible biomass. This study investigates the hypothesis that geometric factors are much more influential in determining structural strength than tissue properties. To study these influences, both physical and in silico experiments were used. First, maize stems were tested in three-point bending. Specimen-specific finite element models were created based on x-ray computed tomography scans. Models were validated by comparison with experimental data. Sensitivity analyses were used to assess the influence of structural parameters such as geometric and material properties. As hypothesized, geometry was found to have a much stronger influence on structural stability than material properties. This information reinforces the notion that deficiencies in tissue strength could be offset by manipulation of stalk morphology, thus allowing the creation of stalks which are both resilient and digestible.

Increasing photosynthetic productivity of cereal bioenergy crops as affected by the water content in leaves under mycorrhization of the root system

Purpose. To determine photosynthetic productivity of miscanthus gigantheus and switchgrass as affected by leaf water content under mycorrhization of their roots. Methods. Field, laboratory, and statistical. Results. The obtained results indicate that the use of vesicular-arbuscular mycorrhizal (VAM) preparations Mycofriend (fungus Trichoderma harzianum RIFAI.), Mikovital (fungus Tuber melanosporum VITTAD.), and nitrogen-fixing preparation Florobacillin (Bacillus subtilis Cohn.) helps to increase water content in the leaves of such cereal bioenergy crops as miscanthus gigantheus and switchgrass. In particular, in all vegetation periods, in the treatments with Mycofriend, the water content in miscanthus gigantheus leaves was higher by 11.2–20.1% than in the control, while in switchgrass it was higher by 16.9–20.5% than in the control. In the treatments with Mikovital and Florobacillin, leaf water content ranged in miscanthus from 7.1 to 15.6% and from 5.8 to 11.7%, respectively, and in switchgrass, from 11.6 to 14.7% and from 7.0 to 10.2%, respectively. The photosynthetic productivity of these crops is affected by the water content in the leaves. There is a close correlation between these factors (correlation coefficient 0.95–0.96). Conclusions. Root application of biological plant products Mycofriend, Mikovital and Florobacillin improves water content in the leaves of cereal bioenergy crops, such as miscanthus gigantheus and switchgrass, and increases their photosynthetic productivity.

Dry matter and ash content in leaves and stems of bioenergy crops

Purpose. Determine the content of dry mass and ash in the leaves and stems of bioenergy crops (miscanthus, switchgrass, willow). Methods. Samples were taken at the end of the growing season (October). The dry matter content was determined by thermogravimetric method, ash content by burning in a muffle furnace. Results. The dry matter content of the leaves varied depending on the year of research and crop. Thus, on average over the years of research, this figure was highest in switchgrass and willow, 65.8–66.0% with an ash content of 4.3–4.5%. The content of dry mass in miscanthus leaves was 9–10% lower compared to other energy crops. The ash content was at the level of 2.8% or 1.5–1.6 times. Physico-chemical parameters of the leaves of energy crops have changed since one year of the study. In miscanthus leaves it varied from 59.9 to 60.2%, switchgrass from 54.5 to 76.9%, and willow from 60.7 to 72.2%. The ash content varied in a smaller range of all energy crops. In the stems of miscanthus, the dry matter content was in the range from 57.5% to 58.9%, in switchgrass it was the largest, from 54.9 to 65.3%, and in the stems of willow from 51.3 to 57.1% over the years of research. The stems of all energy crops had a lower ash content compared to the leaves. Thus, this indicator in miscanthus leaves was at the level of 1.5–1.6%, switchgrass 1.3–2.2%, willow 2.0–2.5% (1.5–3.0 times). Conclusions. The content of dry mass and ash in the leaves and stems varies depending on the type of energy crop. The highest content of dry mass is formed in the leaves of switchgrass (54.5–76.9%) and willow 60.7–72.2%. The ash content is 4.1–4.9% and 4.0–4.5%, respectively. The content of dry mass in miscanthus stems is 57.5–58.9%, switchgrass 54.9–65.3%, willow 51.3–57.1%. The content of ash in the stems of miscanthus is 1.5–1.6%, switchgrass 1.3–2.2, willow 2.0–2.5% or 1.5–3.0 times.

Jerusalem Artichoke as a Fodder Crop for Food Security Solutions

Being a valuable source of inulin, fructose and pectin, Jerusalem artichoke (Helianthus tuberosus L.) is one of the most promising bioenergy crops for common usage. Animals have been reported to eat both Jerusalem artichoke green mass and tubers with pleasure. On the one hand, Jerusalem artichoke is cultivated on the area of about 3 thousand hectares in Russia. On the other hand, there are more than 200 crop species. So it is critical to choose a proper variety suitable both for soil and climatic conditions. The purpose of the research is to study Jerusalem artichoke, taking into account varietal characteristics appropriate for forage production. Research objects – varieties of Jerusalem artichoke: early ripening Skorospelka (RF); mid-early Vylgortskiy (RF); mid-season Dieticheskiy (RF), Kaluzhskiy (RF), Korenevskiy (RF), Nadezhda (RF), Nakhodka (RF), Podmoskovniy (RF), Sireniki (RB), Blank Brekos (France), Violet de Rense (France); late ripening Interest (RF), Interest 21 (RF), Novosti VIRa (RF), Tadzhikskiy Krasniy (USSR), Spindle (Germany). The soil for evaluating Jerusalem artichoke varieties was from experimental plot base "Korenevo". It is characterized as sod-slightly podzolic sandy loam. The field trial was established and the records and observations were carried out in accordance with the requirements of the field experiment methodology (1985), and the Program and methodology for evaluating Jerusalem artichoke varieties in test nurseries (2014). The varieties Vylgortskiy, Dieticheskiy, Nadezhda, Nakhodka, Sireniki, Skorospelka, Blank Brekos and Kaluzhskiy were found to reach due height of 155 - 170 cm at the end of the growing season; the varieties Podmoskovniy, Interest reached proper height of 175 - 208 cm; the varieties Interest 21, Tadzhikskiy and Violet de Rense were about 220 - 235 cm in hight; as for the varieties Korenevskiy, Novost VIRa, Spindlу their hight was 270 - 280 cm. According to aggregate amount of feed units per 1 ha, the following varieties have been shown to be the most reasonable for fodder production: Novost VIRa (22,438 fodder units), Nadezhda (19,928 fodder units), Korenevskiy (17,798 fodder units), Shpindle (16,887 fodder units), Dieticheskiy (16,395 fodder units), and Interest (16,116 fodder units). The highest total coefficient of energy efficiency has been found in the following varieties: Novost VIRa – 3.09, Tadzhikskiy – 2.78; Spindle – 2.68; Korenevskiy – 2.43; Interest – 2.10; Skorospelka – 1.98. The results of experimental and theoretical studies obtained were verified on-the-farm conditions based on a seed-speciality farm LLC Kaluga-Agro (the Kaluga region) and demonstrated beneficial effect.

Application of Organic Amendments to Cadmium-contaminated Soils for Phytostabilization Potential by Dicotyledonous Bioenergy Crops

Acacia (Acacia mangium), jatropha (Jatropha curcas), and cassava (Manihot esculenta) were cultivated in a greenhouse to see how organic amendments affected plant survival and accumulation of cadmium (Cd) in plant tissues. The study plants are bioenergy crops, which are advantageous to phytomanagement because they provide a significant economic benefit to local residents and farmers in the agricultural sector while also simultaneously reducing Cd entry into food webs through consumption. In this study, bone meal/bat manure and leonardite/bat manure were the key organic amendments that promoted the best growth performances in acacia (growth rate in dry biomass; GRDB 24.2) and cassava (GRDB 22.2), respectively, while jatropha preferred bone meal (GRDB 17.2). However, leonardite/bone meal considerably reduced Cd uptake values in whole plant tissues of acacia and cassava (35 mg plant-1 and 119.1 mg plant-1, respectively), while bone meal/chicken manure greatly reduced Cd uptake values in jatropha (127.8 mg plant-1). Cassava is a Cd excluder; however, it may not be a useful bioenergy crop to cultivate in Cd soil because it displayed toxicity symptoms after harvesting. The best plant for phytomanagement in this study was jatropha, which demonstrated substantial growth biomass and Cd accumulation, followed by acacia.

Nonadditive gene expression is correlated with nonadditive phenotypic expression in interspecific triploid hybrids of willow (Salix spp.)

Many studies have highlighted the complex and diverse basis for heterosis in inbred crops. Despite the lack of a consensus model, it is vital that we turn our attention to understanding heterosis in undomesticated, heterozygous, and polyploid species, such as willow (Salix spp.). Shrub willow is a dedicated energy crop bred to be fast-growing and high yielding on marginal land without competing with food crops. A trend in willow breeding is the consistent pattern of heterosis in triploids produced from crosses between diploid and tetraploid species. Here, we test whether differentially expressed genes are associated with heterosis in triploid families derived from diploid S. purpurea, diploid S. viminalis, and tetraploid S. miyabeana parents. Three biological replicates of shoot tips from all family progeny and parents were collected after 12 weeks in the greenhouse and RNA extracted for RNA-Seq analysis. This study provides evidence that nonadditive patterns of gene expression are correlated with nonadditive phenotypic expression in interspecific triploid hybrids of willow. Expression-level dominance was most correlated with heterosis for biomass yield traits and was highly enriched for processes involved in starch and sucrose metabolism. In addition, there was a global dosage effect of parent alleles in triploid hybrids, with expression proportional to copy number variation. Importantly, differentially expressed genes between family parents were most predictive of heterosis for both field and greenhouse collected traits. Altogether, these data will be used to progress models of heterosis to complement the growing genomic resources available for the improvement of heterozygous perennial bioenergy crops.

Enriched root bacterial microbiome in invaded vs native ranges of the model grass allotetraploid Brachypodium hybridum

Invasive species can shift the composition of key soil microbial groups, thus creating novel soil microbial communities. To better understand the biological drivers of invasion, we studied plant-microbial interactions in species of the Brachypodium distachyon complex, a model system for functional genomic studies of temperate grasses and bioenergy crops. While Brachypodium hybridum invasion in California is in an incipient stage, threatening natural and agricultural systems, its diploid progenitor species B. distachyon is not invasive in California. We investigated the root, soil, and rhizosphere bacterial composition of Brachypodium hybridum in both its native and invaded range, and of B. distachyon in the native range. We used high-throughput, amplicon sequencing to evaluate if the bacteria associated with these plants differ, and whether biotic controls may be driving B. hybridum invasion. Bacterial community composition of B. hybridum differed based on provenance (native or invaded range) for root, rhizosphere, and bulk soils, as did the abundance of dominant bacterial taxa. Bacteroidetes, Cyanobacteria and Bacillus spp. (species) were significantly more abundant in B. hybridum roots from the invaded range, whereas Proteobacteria, Firmicutes, Erwinia and Pseudomonas were more abundant in the native range roots. Brachypodium hybridum forms novel biotic interactions with a diverse suite of rhizosphere microbes from the invaded range, which may not exert a similar influence within its native range, ostensibly contributing to B. hybridum’s invasiveness. These associated plant microbiomes could inform future management approaches for B. hybridum in its invaded range and could be key to understanding, predicting, and preventing future plant invasions.

Global cooling induced by biophysical effects of bioenergy crop cultivation

Bioenergy crop with carbon capture and storage (BECCS) is a key negative emission technology to meet carbon neutrality. However, the biophysical effects of widespread bioenergy crop cultivation on temperature remain unclear. Here, using a coupled atmosphere-land model with an explicit representation of lignocellulosic bioenergy crops, we find that after 50 years of large-scale bioenergy crop cultivation following plausible scenarios, global air temperature decreases by 0.03~0.08 °C, with strong regional contrasts and interannual variability. Over the cultivated regions, woody crops induce stronger cooling effects than herbaceous crops due to larger evapotranspiration rates and smaller aerodynamic resistance. At the continental scale, air temperature changes are not linearly proportional to the cultivation area. Sensitivity tests show that the temperature change is robust for eucalypt but more uncertain for switchgrass among different cultivation maps. Our study calls for new metrics to take the biophysical effects into account when assessing the climate mitigation capacity of BECCS.