• Energy Research

Abstract Willow nursery plantations for cuttings' production, which provide planting material for new, improved varieties, can be set up in greater densities and must be harvested in one-year cycles. Therefore, the aim of this study was to determine the effect of planting density on the survival rate, yield and production potential of cuttings of two varieties and three clones in ten successive one-year harvest cycles. The experiment was conducted in the years 2004–2013 in northern Poland. Significant differentiation regarding the biomass yield and the number of cuttings was demonstrated not only between the planting densities, but also between the varieties/clones and the interactions between those factors. The final survival rate was close to 85% with a planting density of 12 000 ha −1 and 24 000 ha −1 . However, the survival rate was half that at the highest planting density. The varieties and clones differed in their morphological features, which affected their yield, both as chips and cuttings number. The best results were achieved for the UWM 095 clone and the Tur variety. The yield varied over the next ten years, but it was not found to decrease as the plantation aged. An increase in planting density from 12 000 ha −1 to 24 000 ha −1 resulted in greater yield, but a further increase to 48 000 ha −1 and 96 000 ha −1 did not bring such effects. The production of cuttings could bring more than 20 times higher potential income compared to the production of chips for energy purposes.

Abstract Willow nursery plantations for cuttings' production, which provide planting material for new, improved varieties, can be set up in greater densities and must be harvested in one-year cycles. Therefore, the aim of this study was to determine the effect of planting density on the survival rate, yield and production potential of cuttings of two varieties and three clones in ten successive one-year harvest cycles. The experiment was conducted in the years 2004–2013 in northern Poland. Significant differentiation regarding the biomass yield and the number of cuttings was demonstrated not only between the planting densities, but also between the varieties/clones and the interactions between those factors. The final survival rate was close to 85% with a planting density of 12 000 ha −1 and 24 000 ha −1 . However, the survival rate was half that at the highest planting density. The varieties and clones differed in their morphological features, which affected their yield, both as chips and cuttings number. The best results were achieved for the UWM 095 clone and the Tur variety. The yield varied over the next ten years, but it was not found to decrease as the plantation aged. An increase in planting density from 12 000 ha −1 to 24 000 ha −1 resulted in greater yield, but a further increase to 48 000 ha −1 and 96 000 ha −1 did not bring such effects. The production of cuttings could bring more than 20 times higher potential income compared to the production of chips for energy purposes.

The biomass of Salix viminalis is the most highly valued source of green energy, followed by S. schwerinii, S. dasyclados and other species. Significant variability in productivity and leaf rust resistance are noted both within and among willow species, which creates new opportunities for improving willow yield parameters through selection of desirable recombinants supported with molecular markers. The aim of this study was to identify quantitative trait loci (QTLs) linked with biomass yield-related traits and the resistance/susceptibility of Salix mapping population to leaf rust. The experimental material comprised a mapping population developed based on S. viminalis × S. schwerinii hybrids. Phenotyping was performed on plants grown in a field experiment that had a balanced incomplete block design with 10 replications. Based on a genetic map, 11 QTLs were identified for plant height, 9 for shoot diameter, 3 for number of shoots and 11 for resistance/susceptibility to leaf rust. The QTLs identified in our study explained 3%–16% of variability in the analyzed traits. Our findings make significant contributions to the development of willow breeding programs and research into shrubby willow crops grown for energy.

The biomass of Salix viminalis is the most highly valued source of green energy, followed by S. schwerinii, S. dasyclados and other species. Significant variability in productivity and leaf rust resistance are noted both within and among willow species, which creates new opportunities for improving willow yield parameters through selection of desirable recombinants supported with molecular markers. The aim of this study was to identify quantitative trait loci (QTLs) linked with biomass yield-related traits and the resistance/susceptibility of Salix mapping population to leaf rust. The experimental material comprised a mapping population developed based on S. viminalis × S. schwerinii hybrids. Phenotyping was performed on plants grown in a field experiment that had a balanced incomplete block design with 10 replications. Based on a genetic map, 11 QTLs were identified for plant height, 9 for shoot diameter, 3 for number of shoots and 11 for resistance/susceptibility to leaf rust. The QTLs identified in our study explained 3%–16% of variability in the analyzed traits. Our findings make significant contributions to the development of willow breeding programs and research into shrubby willow crops grown for energy.

Perennial crops harvested in short rotations provide substantial amounts of biomass. This study determined the survival rate, biometric features and yield of fresh and dry biomass of 15 willow genotypes (including seven varieties and eight clones), cultivated at two different sites in two consecutive three-year harvest rotations. The study revealed the very high impact of the genotype (81% of the total variance) on the willow yield. The harvest rotation, along with the genotype, had a significant impact on the plant survival rate and the number of shoots per stool. Willow biomass was mainly affected by the plant height, its survival rate and shoot diameter. The significantly highest fresh (106 Mg ha−1) and dry biomass yield (54.0 Mg ha−1) was obtained from the Żubr variety of S. viminalis, which distinguished this variety from the other genotypes. The mean yield for the best three and five genotypes was 13% and 17% lower, respectively, and the mean yield for the whole experiment was 37% lower compared to the mean yield of the best variety (Żubr). Therefore, the choice of a willow genotype is of key importance for successful willow production.

Perennial crops harvested in short rotations provide substantial amounts of biomass. This study determined the survival rate, biometric features and yield of fresh and dry biomass of 15 willow genotypes (including seven varieties and eight clones), cultivated at two different sites in two consecutive three-year harvest rotations. The study revealed the very high impact of the genotype (81% of the total variance) on the willow yield. The harvest rotation, along with the genotype, had a significant impact on the plant survival rate and the number of shoots per stool. Willow biomass was mainly affected by the plant height, its survival rate and shoot diameter. The significantly highest fresh (106 Mg ha−1) and dry biomass yield (54.0 Mg ha−1) was obtained from the Żubr variety of S. viminalis, which distinguished this variety from the other genotypes. The mean yield for the best three and five genotypes was 13% and 17% lower, respectively, and the mean yield for the whole experiment was 37% lower compared to the mean yield of the best variety (Żubr). Therefore, the choice of a willow genotype is of key importance for successful willow production.

Abstract This article presents the results of an 11-year field experiment (2008–2018) conducted in Poland to investigate the biomass yield and energy efficiency of fodder galega (Galega orientalis Lam.) in high-input and low-input production technologies. The demand for energy in the production of fodder galega biomass ranged from 13.0 to 14.2 (year of plantation establishment) to 6.4–8.2 GJ ha−1 (years 2–11). Agricultural intensification increased energy inputs by 11% on average. Dry matter yield (DMY) and energy output peaked in years 4 and 5 (14.7–15.3 Mg ha−1 and 122.4–131.1 GJ ha−1, respectively). In the high-input production technology, DMY was 0.62 Mg ha−1 y−1 higher, energy output was 4.9 GJ ha−1 y−1 higher, the maximum DMY was achieved one year later, and the rate of decrease in biomass yield and energy output in the last years of the experiment (years 9–11) was 30% lower in comparison with the low-input system. The energy efficiency ratio of fodder galega ranged from 2.28 to 2.42 (year 1) to 8.04–16.53 (years 2–11). Productivity was 4% higher in the low-input than in the high-input technology. Fodder galega biomass was characterized by higher energy efficiency in the high-input technology (by approx. 2–12%) only in the last years of the experiment (years ≥10).

Abstract This article presents the results of an 11-year field experiment (2008–2018) conducted in Poland to investigate the biomass yield and energy efficiency of fodder galega (Galega orientalis Lam.) in high-input and low-input production technologies. The demand for energy in the production of fodder galega biomass ranged from 13.0 to 14.2 (year of plantation establishment) to 6.4–8.2 GJ ha−1 (years 2–11). Agricultural intensification increased energy inputs by 11% on average. Dry matter yield (DMY) and energy output peaked in years 4 and 5 (14.7–15.3 Mg ha−1 and 122.4–131.1 GJ ha−1, respectively). In the high-input production technology, DMY was 0.62 Mg ha−1 y−1 higher, energy output was 4.9 GJ ha−1 y−1 higher, the maximum DMY was achieved one year later, and the rate of decrease in biomass yield and energy output in the last years of the experiment (years 9–11) was 30% lower in comparison with the low-input system. The energy efficiency ratio of fodder galega ranged from 2.28 to 2.42 (year 1) to 8.04–16.53 (years 2–11). Productivity was 4% higher in the low-input than in the high-input technology. Fodder galega biomass was characterized by higher energy efficiency in the high-input technology (by approx. 2–12%) only in the last years of the experiment (years ≥10).