• Energy Research

Abstract In South Mediterranean conditions, during periods of severe drought mandatory watering restrictions can be established, such as the prohibition to irrigate crops. There is a need for growers of perennial crops such as A. donax to have data on crop response to dry conditions in order to decide on whether to keep or remove the crop. In this work, a four-year-old crop of nine A. donax ecotypes grown under optimal irrigation conditions was subjected to dry conditions for two years in a Xeric Mediterranean environment. Ecotypes performance in the two water conditions was assessed in order to provide data for growers to support their decision. Significant differences were found between ecotypes and water regimes for yield parameters. The interaction of water regime-ecotype was also significant, showing that the effect of the water regime change depended on the ecotype. The relative yield reduction of the mature crop ranged from 53% to 78%; this was as a result of the tough climate conditions in central Spain during the period of vegetative growth of A. donax. Over the whole experiment, an ecotype from South Greece outperformed and could be considered as a reference of the A. donax biomass potential in this environment. Further studies would be needed to assess the genetic distance among ecotypes, as well as to confirm the superiority of this ecotype in different environments.

Concerns about land and water use have led to research on perennial grasses as energy crops for marginal lands, including abandoned lands, low fertility soils and water-deficit areas. The potential of this type of crops should be assessed not only in terms of yield but also in terms of quality of the crop produce. The aim of this work was to investigate if water-deficit conditions affect the energy and compositional characteristics of giant reed when grown under a continental-Mediterranean climate. A two-year field experiment was designedwith two sources of variation: water-deficit level (three levels or treatments) and biomass fraction (leaves, stalks), and thirteen variables (biomass properties).It was found that the differences between the studied water-deficit treatments were small for most variables; on the contrary, the differences between the properties of the leaf fraction and the stalk biomass were much higher and often statistically significant.Therefore, the biomass partitioning into leaves and stalks was revealed as the main factor influencing the quality of giant reed biomass. Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 351-355

Carbon distribution in the stem of 2-year-old cork oak plants was studied by (14)CO(2) pulse labeling in late spring in order to trace the allocation of photoassimilates to tissue and biochemical stem components of cork oak. The fate of (14)C photoassimilated carbon was followed during two periods: the first 72 h (short-term study) and the first 52 weeks (long-term study) after the (14)CO(2) photosynthetic assimilation. The results showed that (14)C allocation to stem tissues was dependent on the time passed since photoassimilation and on the season of the year. In the first 3 h all (14)C was found in the polar extractives. After 3 h, it started to be allocated to other stem fractions. In 1 day, (14)C was allocated mostly to vascular cambium and, to a lesser extent, to primary phloem; no presence of (14)C was recorded for the periderm. However, translocation of (14)C to phellem was observed from 1 week after (14)CO(2) pulse labeling. The phellogen was not completely active in its entire circumference at labeling, unlike the vascular cambium; this was the tissue that accumulated most photoassimilated (14)C at the earliest sampling. The fraction of leaf-assimilated (14)C that was used by the stem peaked at 57% 1 week after (14)CO(2) plant exposure. The time lag between C photoassimilation and suberin accumulation was ∼8 h, but the most active period for suberin accumulation was between 3 and 7 days. Suberin, which represented only 1.77% of the stem weight, acted as a highly effective sink for the carbon photoassimilated in late spring since suberin specific radioactivity was much higher than for any other stem component as early as only 1 week after (14)C plant labeling. This trend was maintained throughout the whole experiment. The examination of microautoradiographs taken over 1 year provided a new method for quantifying xylem growth. Using this approach it was found that there was more secondary xylem growth in late spring than in other times of the year, because the calculated average cell division time was much shorter.

Mechanisation has been recognised as a key point for the promotion of dedicated energy crops like Arundo donax L. This work reports the performance of commercial machinery modified and assembled by a Spanish manufacturer of agricultural machinery, which was tested in an arundo crop for biomass. Operational speeds and other data gathered during the harvesting tests are given in this article. Actual yield in baled biomass and biomass properties after 8-month storage in open field were determined as well. Results show that the strategy of two-step harvesting: stalk cutting & crushing and biomass collection and baling with this specific machinery is feasible in wintertime. Physical, energy and chemical properties of baled biomass did not change after 8 months. On the whole, the machinery used in these tests performed well; however, the working height of the baler should be improved to avoid damages to irrigation pipes. Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 302-307

In this work a comparative study of whole biomass productivity of several triticale (x triticosecale) and rye (Secale cereale) varieties experimented on different locations of Spain and their energy content is conducted. Varieties are selected for biomass production so that they do not compete with grain cereals grown for food or traditional purposes. Furthermore, the proposed crops are very hardy crops that could represent an option for the cultivation of dry land that have been abandoned for conventional crops because of their poor soil or harsh climate conditions. Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 591-595

The aim of this work was to study the dynamics of seed germination of artichoke thistle (Cynara cardunculus L. var. altilis DC), a perennial herb that has been proposed as an energy crop for solid biofuels and other applications in the Mediterranean region, where it can be grown in dry lands. Crop establishment is crucial for perennials and in the case the cynara crop, it depends on the success of seed germination. In this work, the effects of the environmental factors: temperature, darkness/light exposure and water potential on cynara seed germination are studied. Results show that cynara seeds germinate best in dark and that low water potentials and low temperatures decrease seed germination. Optimal conditions for cynara germination combine darkness, 20-30ºC temperature and water potentials between 0 and -0.25 MPa. Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 339-344

This study addresses the challenge of producing feedstocks for bioenergy and bio-based products in a non-land-dependent system based on the recently-developed concept of Green Floating Filter (GFF). In this system, cattails are grown on floating supports placed in eutrophic water bodies in order to form a biomass mat that contributes to water treatment; the produced biomass is fully harvested at the end of the growth cycle. In this work datasets of key parameters concerning GFF performance were built for the proof-of-concept of GFFs. Results highlighted the relationship between biomass production and water quality, with lower biomass production in the treatment with lowest COD. Biomass partitioning was slightly affected by the water quality, at the contamination levels studied; the submerged biomass represented 45.6% of the total biomass (dry mass) on average, partitioned into 79.5% rhizomes and 20.5% roots at the February harvest. The starch content of the submerged biomass varied with harvest date and biomass partitioning. Main conclusion was that the potential of GFF system for bioethanol and biobased products is high, but it clearly relies on the nutrient water level and the harvest date. Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 207-212

Prickly-pear features morphological and physiological adaptations to hot arid conditions which make this plant species an ideal crop for arid and semi-arid regions. It is a perennial with a distinct morphology, typically a succession of cladodes. This fact allows the development of a specific allometric method for the estimation of the biomass production of this crop. A close relationship was reported in the literature between non-destructive measurements of cladodes and biomass dry weight. In this work, seasonal variations of the regression line that correlates cladodes dry weights to non-destructive measurements of cladodes are studied. Results showed that a single linear equation can be assumed for most of the growth cycle. Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 596-600

The purpose of this research is to use helophytes as floating filters in an artificial aqautic system for water treatment in Lake Cheimaditida and irrigation channels (Western Macedonia, 40 km southeast of Florina, Greece) and in irrigation channels and pods (broader region of Avila, province 150 km east of Madrid, Spain). By using these floating filters, the challenge of producing feedstock for bioenergy without using agricultural land will be achieved. There are several factors that should be considered in order to have successful results such ascharacteristics of the water body and its surroundings,planting density and distribution, etc. Also, there are some criteria that one site must meet for being suitable for GFF establishment. Some of them are the protection of the environment, the environmental conditions for helophytes growth, conditions on the area, etc. Hopefully, the findings of this study may be useful for both bioenergy production with no land use and for contaminated water treatment. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 209-213