Energy Willow Research Articles

Microanatomical Properties of Energy Willow (Salix spp.) Leaves after Exposure to Potentially Toxic Elements from Wastewater Solids and Wood Ash

Microanatomical Properties of Energy Willow (Salix spp.) Leaves after Exposure to Potentially Toxic Elements from Wastewater Solids and Wood Ash

Doubling genome size of energy willow affects woody stem cell wall structure, chemistry, and biogas yield

Doubling genome size of energy willow affects woody stem cell wall structure, chemistry, and biogas yield

Manifestation of Triploid Heterosis in the Root System after Crossing Diploid and Autotetraploid Energy Willow Plants.

Successful use of woody species in reducing climatic and environmental risks of energy shortage and spreading pollution requires deeper understanding of the physiological functions controlling biomass productivity and phytoremediation efficiency. Targets in the breeding of energy willow include the size and the functionality of the root system. For the combination of polyploidy and heterosis, we have generated triploid hybrids (THs) of energy willow by crossing autotetraploid willow plants with leading cultivars (Tordis and Inger). These novel Salix genotypes (TH3/12, TH17/17, TH21/2) have provided a unique experimental material for characterization of Mid-Parent Heterosis (MPH) in various root traits. Using a root phenotyping platform, we detected heterosis (TH3/12: MPH 43.99%; TH21/2: MPH 26.93%) in the size of the root system in soil. Triploid heterosis was also recorded in the fresh root weights, but it was less pronounced (MPH%: 9.63-19.31). In agreement with root growth characteristics in soil, the TH3/12 hybrids showed considerable heterosis (MPH: 70.08%) under in vitro conditions. Confocal microscopy-based imaging and quantitative analysis of root parenchyma cells at the division-elongation transition zone showed increased average cell diameter as a sign of cellular heterosis in plants from TH17/17 and TH21/2 triploid lines. Analysis of the hormonal background revealed that the auxin level was seven times higher than the total cytokinin contents in root tips of parental Tordis plants. In triploid hybrids, the auxin-cytokinin ratios were considerably reduced in TH3/12 and TH17/17 roots. In particular, the contents of cytokinin precursor, such as isopentenyl adenosine monophosphate, were elevated in all three triploid hybrids. Heterosis was also recorded in the amounts of active gibberellin precursor, GA19, in roots of TH3/12 plants. The presented experimental findings highlight the physiological basics of triploid heterosis in energy willow roots.

Metal Accumulation and Tolerance of Energy Willow to Copper and Nickel under Simulated Drought Conditions

The aim of this study was to determine the effect of drought on the accumulation and tolerance of energy willow (Salix viminalis L. var. ‘Gigantea’) to copper (Cu) and nickel (Ni) in the context of phytoremediation potential of the plant and biomass production under adverse water conditions. Drought was simulated with polyethylene glycol (PEG-6000. 5%), and metals were added at a concentration of 1 mM. Plants were cultivated in greenhouse conditions for 21 days according to the experimental variants: control, Cu, Ni, PEG, PEG + Cu and PEG + Ni. The results indicate high toxicity of Cu (chlorosis, necrosis, decrease in biomass, plant dehydration, increase in the content of proline and phenolic compounds), and PEG + Cu co-treatment increased the toxicity of the metal. Ni applied at the same concentration did not cause toxicity symptoms. The willow exhibits the ability to accumulate Ni, and mutual application of PEG + Ni increased Ni uptake to new shoots. Cu caused elevated accumulation of proline and phenolics in leaves accompanied with a decreased carbon and nitrogen content in roots in favor of young shoots. Both metals and drought led to disruption in the content of mineral nutrients (Ca, Mg, Fe). Due to high tolerance to Ni and drought, S. viminalis var. ‘Gigantea’ bears high potential for biomass production on Ni-polluted sites with accompanying metal uptake increased under water deficit.

STUDY OF THE UNLOADING AND SELECTION PROCESS OF ENERGY WILLOW CUTTINGS FOR THE CREATION A PLANTING MACHINE

The article highlights the problems of ensuring continuous unloading of energy willow cuttings from slotted bunkers. During the free discharge of rod-like bodies, such phenomena as crypt formations, distortions, pinching occur, which stop the discharge under the action of gravity. Finding such parameters, under which the system will work evenly and without stops, will make it possible to automate many processes related to working with such material, in particular, when developing a piecemeal selection mechanism for a planting machine. The study revealed and analyzed the possible forms of vaults that are formed during unloading from creating obstacles to movement. As a hopper model, for unloading cuttings, a slotted hopper in the form of two walls located at angles to the horizontal plane is considered. These walls form an unloading slot with adjustable width of the unloading window and an adjustable tilt angle. During the study, vaults were recorded, which are formed at different parameters of the bunker during free unloading. As research has shown, in order to ensure uninterrupted unloading of cuttings, there is such a width of the unloading window of the hopper, which will ensure uniform pouring of cuttings without crypt formations and stops associated with this process. The analysis of continuous discharge of rod-like material established that for cuttings of energy willow, the width of the window, which ensures continuous discharge, is 8-12 cm.

THE DISTRIBUTION OF CASH EXPENSES FOR THE CREATION OF BIOENERGY WILLOW PLANTATIONS IN UKRAINE

The economic cost analysis of creating energy willow plantations in Ukraine is provided in the present paper. The experience of creating bioenergy willow plantations at scientific and industrial institutions in Ukraine has been used in the paper. The purpose of this scientific work is to conduct an analysis of the structure of cash expenses for the creation of bioenergy willow plantations based on the experience of various institutions of Ukraine. The analysis is based on a technological map created during the study on drained peat lands at Panfyly Research Station. Analyzing the cost structure by category, the data obtained during the creation of bioenergy willow plantations of Salix Energy LLC and the Institute of Bioenergy Crops and Sugar Beet were also taken into account. After analyzing all the technology stages of growing bioenergy willow, it was revealed that the most expensive is the second stage associated with the preparation for planting and planting willow cuttings in the context of the pricing policy in Ukraine. In general, more than 60% of all expenses fall upon the first year of cultivation. According to the experience of Ukrainian institutions, the cost structure will have a significant shift towards planting material - 55-60%. The remaining costs are distributed during the use of equipment in the field, which constitute 26-30% and transportation costs respectively are 12-19%.

Expression of triploid heterosis in the biomass productivity of energy willow plants under salinity stress

Bioenergy production from short rotation woody species grown on saline soil provides multiple environmental advantages. Breeding of energy willow for salinity tolerance can support green energy utilization. Here, we quantify triploid heterosis in biomass traits under salt stresses. Crosses between diploid cultivars (Tora and Inger) and our autotetraploid plants (PPE-2/6 and PPE-7) resulted in TH16/24 and TH21/2 triploid hybrid genotypes. Growth characteristics of shoots and roots of triploid hybrids and their parental plants were monitored by pixel-based phenotyping under high salt stress (NaCl 2.0 g kg −1/EC: 8.71 mS cm−1) in greenhouse. Different values of Mid-Parent Heterosis (MPH %) were recorded by comparing these two crossing combinations and top or above views (for TH16/24 plants: 3.66% (side pixels) and 22.25% (above pixels) and for TH21/2 plants: 63.30% (side pixels) and 72.10% (above pixels). At the end of the growing period, considerable MPH values were detected in biomass parameters of TH16/24 and TH21/2 plants (shoot length: 18.26%/26.28%; green biomass weight: 40.28%/52.40%; stem diameter: 15.40%/13.98%) in soil with 2.0 g NaCl kg−1. The TH21/2 hybrid plants expressed higher hybrid vigor than plants from the TH16/24 genotype. The TH21/2 hybrid plants exhibited better water use efficiency than their parental plants and showed high MPH values for K+/Na+ ratio in soil containing 2.0 g NaCl kg−1. The presented data support a conclusion that heterosis depending on crossing partners can ensure improvement in salinity tolerance for triploid hybrids. Field experiment has been initiated for the characterization of these hybrids under natural saline soil.

Formation of the above-ground biomass of willow under the influence of varietal characteristics and the type of planting material

Purpose. To reveal the regularities of the formation of the energy willow above-ground biomass structure and evaluate the qualitative and quantitative indicators of the biomass components under the effect of varietal characteristics and the type of planting material.
 Methods. Field experiments were conducted at the experimental field of the Institute of Bioenergy Crops and Sugar Beet (Ksaverivka 2, Kyiv region) located in the zone of unstable moisture in the central part of the Right Bank Forest Steppe of Ukraine in 2019–2022. Cuttings and shoots were harvested in autumn and stored in various ways until planting. In the spring, after planting the shoots in the open ground, the biometric parameters of plants were determined: plant height, stem diameter and the number of stems. The measurements were taken on the same day every month during the three years of the experiment. Two willow varieties were used in the experiment: Salix triandra L. variety 'Panfylska' and S. viminalis L. variety 'Zbruch'.
 Results. The intensity of growth of the above-ground biomass of willow, which also depends on the yield of planting material (cuttings or shoots), was determined by plant height, stem diameter and the number of stems. These indicators were higher in 'Zbruch' compared to 'Panfylska'. Thus, in the second year of vegetation, on the first date of measuring (in spring), the plant height of 'Panfylska' variety was 136.3 cm, while in autumn. on September 21, it was 242.8 cm. In 'Zbruch', the indicators were higher by 12.4 and 13.5 cm, respectively. A similar dependence was found when planting shoots. It should be noted that within one variety, no regular and reliable difference in plant height depending on the type of planting material was found. In the third year of vegetation, a similar dependence of plant height on varietal characteristics was obtained. On average, in 2021–2022, when planting willow cuttings of 'Zbruch' variety, plant height was 276.1 cm in the spring, while in 'Panfylska' it was 20 cm lower (256.1 cm). In autumn, plant height was higher in 'Zbruch' also by 20 cm. Depending on the year of vegetation, the increase in plant height was the greatest in the first year of vegetation compared to the second and third years. Weather conditions during the growing season affected the height of plants; However, in all years of the research it was higher when planting cuttings and shoots of 'Zbruch' compared to 'Panfylska'. No significant influence of variety and the type of planting material on the stem diameter and the number of stems was found in all years of the research.
 Conclusions. Plant height and diameter of stem in dynamics depended on varietal characteristics. In 'Zbruch' variety, when planting cuttings and shoots, the increase in plant height and stem diameter was higher compared to 'Panfylska' both at the beginning of the growing season and in autumn. During the three years of vegetation, varietal characteristics and the type of planting material (cuttings and shoots) showed no significant difference in the plant height, stem diameter and the number of stems.

Indices of Soil and Plant Cover Pollution Due to Re-Introduction of Sediment Water Under the Energy Willow on Aluvisol of Ukraine

Indices of Soil and Plant Cover Pollution Due to Re-Introduction of Sediment Water Under the Energy Willow on Aluvisol of Ukraine

Features of the management of the territories of National nature parks

According to the data of the State Cadastre, at the beginning of 2021, the nature reserve fund counted 8,633 territories and objects with a total area of 4.1 million hectares, which was 6.8% of the country's area. These territories are under the authority of various departments. The main purpose of protected areas is to preserve unique landscapes, species of flora and fauna for future generations. Today, the task is to increase the area of the nature reserve fund. It has been established that national natural parks (NPPs) are one of the largest objects of the protected fund in terms of area. To date, 56 NPPs have been created, which occupy an area of 1,399,161 hectares, which is 30.6% of the entire nature reserve fund. Administrations have been created in national parks to implement the functions entrusted to the park. These include preservation and protection of unique landscapes, conducting scientific research, recreational activities and educational work. The territory of the park includes lands of different purposes. These are mainly forests and other wooded areas (60%), the sea - 21%, inland waters - 6%, agricultural land - 5%, For the effective management of the national natural park, projects are being developed for the organization of the territory of the NPP for the protection, reproduction and recreational use of its natural complexes and objects. At the same time, a project approach is used, which makes it possible to achieve the strategic goals of the park with the help of the proposed measures. It is proposed to grow energy willow on agricultural lands. The environmental component of the project is important, as we have zero carbon emissions when using willow as fuel, which is important at the current price of energy resources. A technological map of growing has been developed, the efficiency of growing energy willow in the territories of the Nobel NPP has been calculated.

Principles of circular economy applied to energy plants in culture. The correlation of soil quality with the valuation potential of willow by-products

Energy plants are used for biomass products such as wood chips ( pellets ) or working wood (OSB boards). For this purpose, you can cultivate willow (Salix alba), artichoke, elephant grass, Chinese reed, energetic hybrid poplars, canary grass, giant cane, and oil tree (source of biodiesel). The study aims, by analyzing the quality of the soil correlated with the composition of the energetic willow bark, to highlight the potential for the valorization of the by-products. In this study, the soil fertility of some Romanian energy willow crops was compared with chernozem with a high input of humus from the Natural Meadow Reserve of Slobozia Mare, Moldavia. Through the analysis of the bark (plant by-product), the determination of salicin from the dry extract, the aqueous extract, and a compressed mixture was sought. Reported to the main macronutrients and pH, the soil of the energy willow crops in Romania is qualitatively similar to Moldavia. Although willow is cultivated primarily as an energy plant (biomass for pellets, biodiesel), if the conditions of the culture area are monitored, the waste represented by the easily removable bark can be utilized because it contains salicin in concentrations that, depending on the area.

Model of Biomass Productivity Under the Influence of Change in the Phytotoxicity of Podzol Soil Due to Reintroduction of Sewage Sludge under Energy Willow

Model of Biomass Productivity Under the Influence of Change in the Phytotoxicity of Podzol Soil Due to Reintroduction of Sewage Sludge under Energy Willow

Features of creating fast-growing and multifunctional field-protecting forest strips in the Forest-Steppe zone of Ukraine

To ensure the maximum protection of agricultural crops from climatic factors unfavorable for their growth and development, it is necessary to create an optimal number of field protection forest strips. In particular, for the Forest-Steppe zone of Ukraine, less than half of the optimal needs are available, which indicates an urgent need for their additional creation. The expediency of creating fast-growing and multifunctional field forest strips is substantiated, and the productivity of new bioenergy crops during their formation for use in beekeeping and as biofuel is determined. For this purpose, a model of the artificial formation of a forest strip with its possible further exploitation is proposed. The most optimal one is to develop the concept of creating field forest strips with the use of multifunctional tree species, which, in addition to the function of wind, water and dust retention, will also perform other economic tasks. In particular, along with their intended purpose, they can be used as raw materials for biofuel production and as early honey plants. For the accelerated creation of field protection forest strips, it is advisable to use mixed 6–8- row plantings, where the middle 2–3 rows are planted with the involvement of tree species, including the use of species valuable as raw materials for beekeeping. These forest strips are complemented on both sides by planted strips of energy crops, which are important for beekeeping and are a valuable resource for obtaining fuel raw materials. For this purpose, it is advisable to plant 10–12 thousand pieces on one hectare poplar cuttings (Populus sp.), 1250 pieces of paulownia plants (Paulownia tomentosa Steud.) with a row width of 2×4 m and 17–18 thousand pieces cuttings of energy willow (Salix viminalis L.). It is also possible to replace part of the poplar cuttings with cuttings of common robinia (Robinia pseudoacacia L.) and linden (Tilia cordata Mill.). The creation of such plantations near settlements will contribute to their significant use of raw materials and will be quite effective in carrying out their main function of ecological stabilization of agro-landscapes.

ФОРМУВАННЯ ЯКОСТІ ВЕГЕТАТИВНОЇ МАСИ ЕНЕРГЕТИЧНИХ КУЛЬТУР РІЗНОЇ ТРИВАЛОСТІ ВЕГЕТАЦІЇ

The research results show that in the samples of switchgrass plants with different vegetation periods the dry matter content varied from 52.40% in the leaves of the 3rd year of vegetation to 77.15% in the leaves of plants of the 8th year of vegetation. In the leaves of miscanthus, the dry matter content varied from 59.35 to 62.30% depending on the duration of the growing season. This figure for energy willow was in the range of 61.23–66.12%. There is a general trend in the content of raw ash in various plant organs: more in the leaves and less in the stem in all variants of the studied plants. Thus, the ash content in switchgrass plants ranged from 1.2% in the stems of plants of the 8th year of vegetation to 4.5% in the leaves of plants of the 10th year of vegetation. The ash content in miscanthus plants ranged from 1.6% to 3.0%, and in willow samples - in the range of 1.9–3.5%. The accumulation of hemicellulose in bioenergetics plants occurs gradually during the growing season. In particular, a slightly higher content of hemicellulose was observing in the stems of bioenergetics plants, less in the leaves. Thus, in switchgrass plants the highest content of hemicellulose was in the stem – 22.65%, and in the leaves 22.75%. In miscanthus plants, the hemicellulose content in the stem ranged from 21.51 to 22.55%, and in the leaves from 21.49 to 22.30%. With regard to energy willow, the distribution of hemicellulose in the plant varied like switchgrass – less in the leaves and more in the stems. The accumulation and distribution of cellulose in bioenergetics plants was similar to hemicelluloses, the leaves were smaller comparing to the stems. In switchgrass plants, the highest cellulose content was in the stems – 42.03–45.49%, and in the leaves – 42.08–45.33%, depending on the duration of the growing season. The distribution of cellulose in switchgrass and energy willow plants changed similarly. Young plants have little lignin, but with age its amount in the tissues increases significantly. Plants accumulate the most lignin in the spring and less in the fall. The accumulation of lignin in samples of bioenergetics plants was different. Its greater content was in the leaves, and less in the stems. Thus, the plants of switchgrass had the highest amount of lignin in the leaves – 18.59% (plants of the 10th year of vegetation), the lowest in the leaves – 15.92% (plants of the 3rd year of vegetation), and in the stems, respectively, 18.02 and 15.90%.

Municipal Sewage Sludge Composting in the Two-Stage System: The Role of Different Bulking Agents and Amendments

This study assessed the effect of different lignocellulosic amendments and bulking agents on compost stability (based on a 4 day respiration activity test, AT4, and self-heating factor, SHF) and maturity (based on the nitrification index Initr and the ratio of C in humic acids, HA, to total organic carbon, TOC, in compost, CHA/TOC). With all feedstock compositions (FCs), the share of sewage sludge was 79% (wet mass). For FC1, wood chips (13.5%) and wheat straw (7.5%) were used as bulking agents and amendments; for FC2, instead of wood chips, energy willow was added; for FC3, pine bark (13.5%) and conifer sawdust (7.5%) were used. All FCs produced stable and mature compost; however, with FC2, the thermophilic phase last 3 days longer than with the other FCs. Moreover, an AT4 value below 10 g O2/kg dry mass (d.m.) was obtained the earliest with FC2 (after 45 days, ca. 15–20 days earlier than with other FCs). With FC2, Initr below 0.5 was obtained in ca. 60 days, 10 days earlier than with FC3 and 30 days earlier than with FC1. The highest net increases in HS (86.0 mg C/g organic matter (OM)) and HA (56.3 mg C/g OM) were also noted with FC2; with other FCs, the concentrations of these compounds were from 1.3- to 1.5-fold (HS) and from 1.4- to 1.9-fold (HA) lower. With FC2, the highest CHA/TOC (15.5%) was also noted, indicating that this compost contained the largest share of the most stable form of organic carbon. The rates of OM removal in the bioreactor ranged from 7.8 to 10.1 g/(kg d.m.·day). The rates of SH and HA formation ranged from 1.63 to 4.83 mg C/(g OM·day) and from 1.23 to 1.80 mg C/(g OM·day), respectively. This means that, through the choice of the amendments and bulking agents, the length of the composting time needed to obtain a stable and mature product can be controlled.

Accounting of growing energy willow in the system of managerial information technologies of energy crop production

Accounting of growing energy willow in the system of managerial information technologies of energy crop production

FIRE AND EXPLOSION CHARACTERISTICS OF ENERGY WILLOW BIOMASS DURING THE SUPERHEATED STEAM DRYING PROCESS

In this paper the explosive and fire properties of energy willow dust were experimentally determined before and after drying with superheated steam at temperatures of 120°C, 140°C, 160°C and 180°C. The conducted research has shown that the parameters of the operation of the installation of drying with superheated steam of the energy willow biomass have a decisive impact on the fire-explosive characteristics of the dust produced. The results indicate that the higher the drying temperature, the stronger the probability of ignition of the willow dust cloud, the faster the flame propagation and the higher the explosion intensity. Although the superheated steam drying installation for energy willow biomass is considered to be safe, the probability of occurrence of a fire or explosion events of the biomass dust-air mixture is likely.

Phytoextraction of toxic elements and chlorophyll fluorescence in the leaves of energy willow (Salix sp.), treated with wastewater solids and wood ash

Open-field small plot long-term experiment was set up during 2011 with willow (Salix triandra × S. viminalis ‘Inger’), grown as a short rotation coppice energy crop in Nyíregyháza, Hungary. The sandy loam Cambisol with neutral pH was treated three times (2011, 2013, and 2016) with 15 t ha–1 municipal sewage sludge compost (MSSC) and with 600 kg ha–1 (2011, 2013) or 300 kg ha–1 (2016) wood ash (WA). In 2018 the MSSC-treated plots were amended with 7.5 t ha–1 municipal sewage sediment (MSS), and 300 kg ha–1 WA. MSSC and WA or MSS and WA were also applied to the soil in combinations during all treatments. Control plots remained untreated since 2011. Repeated application of wastewater solids (MSSC, MSS) and wood ash (WA) significantly enhanced the amounts of As (up to +287%), Ba, Cd (up to +192%), Cu, Mn, Pb, and Zn in the topsoil of willows. The combined application of MSSC+MSS+WA resulted in significantly higher Mn and Zn and lower As Ba, Cd Cr, and Pb concentrations in topsoil than MSSC+MSS treatment of soil without WA. Nitrogen concentrations in leaves of treated plants were generally slightly lower or similar to control. All soil treatments significantly enhanced the uptake or accumulation of nutrient elements (Ca, K, Mg, P) and potentially toxic elements (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in the leaves of willows during 2018, 2019, and 2020. Significantly higher Mn or Zn concentrations were measured in MSSC+MSS+WA than in MSSC+MSS treatments. Significant amounts of Cd (up to 1.11 mg kg–1) or Zn (up to 183 mg kg–1) can be translocated (phytoextracted) from a soil amended with wastewater solids or wood ash to willow leaves. In 2018 the treatments decreased the chlorophyll fluorescence values, while in 2019 and 2020 the light adapted fluorescence yield (Y) values were higher in treated than in control plants.

Study of increasing thermodynamic efficiency and hydrogen amount in the process of solid fuels and biomass gasification

The effect of fuel composition such as hard coal and biomass in fluidized bed on the thermodynamic efficiency of three gasifier types, low heating value (LHV) and syngas composition was studied by simulation in CFD program. The paper presents various small gasification systems with fluidized bed of water-coal mixture and water-biomass mixture both with oxygen (air) and without oxygen. The work presents the extended mathematical model of gasification process taking into account also 13 kinetic chemical reactions enabled to apply them in CFD program. The chemical model is based on surface reactions given in the model of Equivalent Reactor Network (ERN) in Ansys Energetico. Simulation of gasification of different reactor designs enabled to obtain the mass concentration of chemical compounds in the syngas which influenced on thermodynamic efficiency and LHV. Additionally, heating of the gasifier walls by electrical system without air gives higher mass ratio of hydrogen (15%) and carbon monoxide (75%) in the syngas than in the oxidized gasification system. The simulation tests showed high thermodynamic efficiency, taking into account the exergy above 80%, both for the oxygen gasification of hard coal-slurry and biomass as well as for the externally heated gasifier without the supply of oxygen. The highest thermodynamic efficiency 90.5% was obtained during gasification of energy willow in the oxidation reactor due to the large difference in LHV of syngas and fuel. Obtaining the maximum possible mass ratio of H2 in syngas and a high thermal efficiency for the OXGR system from the gasification of subbituminous coal dust occurs at a ratio C/O2 = 0.314 and at almost stoichiometric ratio of C/H2O = 0.63. In the case of gasification of biomass in the form of finely ground energy willow in the OXGR system, these ratios were respectively: O2/C = 1.82 and C/H2O = 0.47. While maintaining the almost stoichiometric ratio C/H2O = 0.75, resulting from the water-gas shift reaction, low heating value of the syngas for the analysed gasification systems was over 25 MJ/kg. The paper shows comparison of mass fractions of CO, H2, H2O, H2S, CO2, O2, CH4, tar and other chemical compounds in the syngas. Application of the gasification reactor with external heated walls and without oxygen inflow produces the syngas without tar and volatile species in comparison to the systems with additional oxygen supply. In oxidized reactors the syngas contains a large amount of CO2 about 25–30% of total mass.

Triploid Hybrid Vigor in Above-Ground Growth and Methane Fermentation Efficiency of Energy Willow.

Hybrid vigor and polyploidy are genetic events widely utilized to increase the productivity of crops. Given that bioenergy usage needs to be expanded, we investigated triploid hybrid vigor in terms of the biology of biomass-related willow traits and their relevance to the control of biomethane production. To produce triploid hybrid genotypes, we crossed two female diploid Swedish cultivars (Inger, Tordis) with two male autotetraploid willow (Salix viminalis) variants (PP-E7, PP-E15). Field studies at two locations and in two successive years recorded considerable midparent heterosis (MPH%) in early shoot length that ranged between 11.14 and 68.85% and in the growth rate between 34.12 and 97.18%. The three triploid hybrids (THs) developed larger leaves than their parental cultivars, and the MPH% for their CO2 assimilation rate varied between 0.84 and 25.30%. The impact of hybrid vigor on the concentrations of plant hormones in these TH genotypes reflected essentially different hormonal statuses that depended preferentially on maternal parents. Hybrid vigor was evinced by an elevated concentration of jasmonic acid in shoot meristems of all the three THs (MPH:29.73; 67.08; 91.91%). Heterosis in auxin-type hormones, such as indole-3-acetic acid (MPH:207.49%), phenylacetic acid (MPH:223.51%), and salicylic acid (MPH:27.72%) and benzoic acid (MPH:85.75%), was detectable in the shoots of TH21/2 plants. These hormones also accumulated in their maternal Inger plants. Heterosis in cytokinin-type hormones characterized the shoots of TH3/12 and TH17/17 genotypes having Tordis as their maternal parent. Unexpectedly, we detected abscisic acid as a positive factor in the growth of TH17/17 plants with negative MPH percentages in stomatal conductance and a lower CO2 assimilation rate. During anaerobic digestion, wood raw materials from the triploid willow hybrids that provided positive MPH% in biomethane yield (6.38 and 27.87%) showed negative MPH in their acid detergent lignin contents (from –8.01 to –14.36%). Altogether, these insights into controlling factors of above-ground growth parameters of willow genotypes support the utilization of triploid hybrid vigor in willow breeding to expand the cultivation of short rotation energy trees for renewable energy production.