The world's most developed countries and the European Union (EU) deem that the renewable energy sources should partly substitute fossil fuels and become a “bridge” to the utilization of other energy sources of the future. This paper will present the possibility of using pruned biomass from fruit cultivars. It will also present the calculation of potential energy from the mentioned raw materials in order to determine the extent of replacement of non-renewable sources with these types of renewable energy. One of the results of the intensive fruit-growing process, in post pruning stage, is large amount of pruned biomass waste. Based on the calculated biomass (kg ha-1) from intensively grown woody fruit crops that are most grown in Croatia (apple, pear, apricots, peach and nectarine, sweet cherry, sour cherry, prune, walnut, hazelnut, almond, fig, grapevine, and olive) and the analysis of combustible (carbon 45.55-49.28%, hydrogen 5.91-6.83%, and sulphur 0.18-0.21%) and non-combustible matters (oxygen 43.34-46.6%, nitrogen 0.54-1.05%, moisture 3.65-8.83%, ashes 1.52-5.39%) with impact of lowering the biomass heating value (15.602-17.727 MJ kg-1), the energy potential of the pruned fruit biomass is calculated at 4.21 PJ.
Miscanthus, a C4 perennial rhizomatous grass, is capable of growing in varied climates and soil types in Europe, including on marginal lands. It can produce high yields with low nutrient inputs when harvested after complete senescence. Senescence induction and rate depend on complex genetic, environmental, and management interactions. To explore these interactions, we analysed four miscanthus hybrids (two novel seed‐based hybrids, GRC 3 [Miscanthus sinensis × sinensis] and GRC 14 [M. sacchariflorus × sinensis]; GRC 15, a novel M. sacchariflorus × sinensis clone; and GRC 9, a standard Miscanthus × giganteus clone) in Italy, Croatia, Germany and the UK. Over all trial locations and hybrids, the average aboveground biomass of the 3‐year‐old stands in August 2020 was 15 t DM ha−1 with nutrient contents of 7.6 mg N g−1 and 14.6 mg K g−1. As expected, delaying the harvest until spring reduced overall yield and nutrient contents (12 t DM ha−1, 3.3 mg N g−1, and 5.5 mg K g−1). At lower latitudes, the late‐ripening M. sacchariflorus × sinensis GRC 14 and GRC 15 combined high yields with low nutrient contents. At the most elevated latitude location (UK), the early‐ripening M. sinensis × sinensis combined high biomass yields with low nutrient offtakes. The clonal Miscanthus × giganteus with intermediate flowering and senescence attained similar low nutrient contents by spring harvest at all four locations. Seasonal changes in yield and nutrient levels analysed in this study provide: (1) a first step towards recommending hybrids for specific locations and end uses in Europe; (2) crucial data for determination of harvest time and practical steps in the valorization of biomass; and (3) key sustainability data for life cycle assessments. Identification of trade‐offs resulting from genetic × environment × management interactions is critical for increasing sustainable biomass supply from miscanthus grown on marginal lands.
Drought tolerance in Miscanthus sinensis is a desirable trait because of its potential use to develop new varieties, namely intra‐specific hybrids, adapted to drought‐prone marginal lands. In this study, drought tolerance was evaluated on 8 M. sinensis intra‐specific hybrids (GRC1–GRC8). Plants were grown in the growth chamber (14/10 h, 25/20°C, 70% relative air humidity and 300 μmol m−2 s−1 irradiance). Drought was induced by withholding irrigation for 21 days (stress phase) and after re‐watering (recovery phase) for 7 days. Nondestructive multispectral 3D images for plant morphology, color, and chlorophyll fluorescence imaging were used to quantify drought‐induced changes on a weekly basis for the entire duration of the experiment. Total leaf area (TLA) and digital biomass (DB) responded most rapidly to water deficits (7–14 days), followed by leaf senescence (14–21 days), and finally, a drop in the maximum efficiency of PSII (Fv/Fm; 21 days). Traits measured on the last day of the drought treatment were used to calculate the phenotypic plasticity. Significant differences in drought susceptibility and phenotypic plasticity were found among the studied hybrids. Drought treatment (21 days) reduced DB and TLA on average by 50%, normalized difference vegetation index (NDVI) by 20% and Fv/Fm from 0.79 (in control) to 0.69 in the less drought‐susceptible hybrids (GRC4 and GRC5), whereas in drought‐sensitive hybrids (GRC2 and GRC3), 21 days of drought reduced DB and TLA on average by 80%, NDVI by 45% and Fv/Fm dropped from 0.79 (in control) to 0.35. The more drought‐resilient hybrids showed lower phenotypic plasticity than their more sensitive counterparts, a stay‐green strategy enabled through lower biomass accumulation and by extension, reduced water usage. Multispectral imaging and image analysis enabled fast and nondestructive quantification of plant morphological and physiological responses under drought conditions and could be used as an effective screening tool for drought susceptibility.