**3.1 Habitat preferences**

Szarvasi-1 energy grass prefers soil conditions similar to common cereals in terms of soil texture, nutrient and water content. However, on lighter soils (e.g. sandy, sandy-silt) it develops faster compared to medium or heavy soils. On sand and sandy soils it can develop seeds in the first year (after spring sowing) and reaches its maximal photosynthetic assimilation one phenophase earlier. The natural habitats of this indigenous plant mainly occur in the central part of Hungary, where the largest sandy areas are located, but it also has an exceptionally natural population on a more clay type soil in a salty marsh.

Considering only the habitats of the natural populations, tall wheatgrass seems to prefer rather alkaline soils where the pH is between 6.5 and 10. However, optimal growing potential and biomass production can be linked to a narrower pH range of 7.5-9. This means that energy grass, in spite of its alkaline origin, can show a more pronounced biomass production in a near neutral soil pH, similarly to the most common cereal cultivations. Slightly acidic soils do not hinder good biomass production, but soil pH below 5.5 negatively affects the yield.

The life span of Szarvasi-1 energy grass cultivation can be 10-15 years long, but the temporal change of biomass production during this time has not yet been monitored sufficiently. We have only one complete data series monitoring the yields of an energy grass field on solonec alkaline soil for more than 10 years. According to this study it takes two years for energy grass cultivation to reach maximal biomass production, which can then be maintained for at least 7 years. At around the tenth year energy grass cultivation starts decrease in yearly biomass production. In semi-arid climates without a ground water table serving as water source for cultivation the durability of the energy grass crops can be much shorter.

The flood tolerance of energy grass is relatively good, especially when the cultivation is at least two or three years old and the tussocks of the individuals are well developed. However, in the first year, the short and weak stems of the juveniles cannot tolerate permanent water cover and die out. Hence, the cultivated energy grass stand opens, the density of the stems declines and the establishment of the grass cultivation remains incomplete. In such a condition, weeds can gain multiple chances to invade and to establish.

High salt concentrations of the soil can be tolerated by Szarvasi-1 energy grass, but only in wet habitats, where a several weeks long seasonal high water table can occur every year. Because of the high salt resistance, Szarvasi-1 energy grass can be used as salt-tolerant forage and can play an important role in the recycling of saline drainage waters for irrigation.

Since *Elymus elongatus* subsp. *ponticus* is a native species of the continental and subcontinental climate in Eastern Europe, it tolerates well the summer high temperatures exceeding daily means of even 30-35 °C, and can also resist cold winter days when the temperature sinks below – 35 °C.

### **3.2 Gas exchange behaviour**

278 Sustainable Growth and Applications in Renewable Energy Sources

*E. hispidus* 4-8 truncate obtuse or acute keel with short

*E. elongatus* 5-11 truncate, glabrous obtuse, awnless two-keeled Szarvasi-1 7-15 truncate obtuse, awnless two-keeled

The glumes of *Elymus* species are indurate-coriaceous, obtuse or truncate, with 1-11 veins, possessing a short awn or no awn at all. The glume can reach half or two thirds of the spikelet in *A. pectiniforme*, two thirds of the spikelet in *E. repens*, and one third of the spikelet in *E. hispidus*, *E. elongatus* and Szarvasi-1 (Fig. 3.). The glumes are 1-3-veined in *A. pectiniforme*, and 3-7-veined in the other taxa. The lemma of *E. elongatus* is obtuse, glabrous, unawned and 5-veined; the palea is two-keeled (Melderis, 1980; Barkworth, 2011). Similarly to other representatives of the Poaceae family, the stigma is feather-like in the *Elymus* genus, where stigmatic secretion is absent even in the mature stage of the stigma, and the receptive surface is discontinuous (Heslop-Harrison Shivanna, 1977). The fruit is a caryopsis.

The evaluated anatomical features allow the differentiation of *E. elongatus* and Szarvasi-1 energy grass from the other investigated members of the *Agropyron*-*Elymus* complex. Szarvasi-1 shows several anatomical traits that enhance drought tolerance, such as a sclerenchymatized epidermis covered by a thick cuticle and dense coverage by nonglandular hairs. On the other hand, the mesomorphic position of stoma guard cells is characteristic of an intermediate water requirement. This dual nature of the habitat tolerance of *Elymus elongatus* cv. Szarvasi-1 has to be taken into account when the new cropfields of

Szarvasi-1 energy grass prefers soil conditions similar to common cereals in terms of soil texture, nutrient and water content. However, on lighter soils (e.g. sandy, sandy-silt) it develops faster compared to medium or heavy soils. On sand and sandy soils it can develop seeds in the first year (after spring sowing) and reaches its maximal photosynthetic assimilation one phenophase earlier. The natural habitats of this indigenous plant mainly occur in the central part of Hungary, where the largest sandy areas are located, but it also

Considering only the habitats of the natural populations, tall wheatgrass seems to prefer rather alkaline soils where the pH is between 6.5 and 10. However, optimal growing potential and biomass production can be linked to a narrower pH range of 7.5-9. This means that energy grass, in spite of its alkaline origin, can show a more pronounced biomass production in a near neutral soil pH, similarly to the most common cereal cultivations. Slightly acidic soils do not hinder good biomass production, but soil pH

has an exceptionally natural population on a more clay type soil in a salty marsh.

**florets/spikelet Glume Lemma Palea** 

narrowing short-awned keel with short

trichomes

trichomes

**Taxon / Character** 

this energy grass are planned.

**3. Ecological requirements** 

below 5.5 negatively affects the yield.

**3.1 Habitat preferences** 

**Number of** 

*A. pectiniforme* 4-8 abruptly

*E. repens* 4-8 acute, tapering acute

Table 3. Reproductive features of wheatgrass (*Elymus* and *Agropyron*) taxa

Tall wheatgrass is classified as C3 plant with cool season characteristics and seasonally different water use efficiency in moderately saline habitats (Bleby et al., 1997; Johnson, 1991). Several cultivars have previously been developed based on adaptability to different environmental conditions in Europe and Asia, but not from ecophysiological perspective. Szarvasi-1 energy grass was developed from a native population of tall wheatgrass (*Elymus elongatus* subsp. *ponticus*) that was adapted to slightly salty habitats. Therefore it was expected that *E. elongatus* cv. Szarvasi-1 will be a good candidate for biomass crop status because it produces large amounts of organic matter with relatively broad tolerance spectra and a high adaptability to different environments. Here we review the current knowledge on environmental gas exchange responses of Szarvasi-1 energy grass under greenhouse and field conditions to different environmental parameters such as temperature, light, air humidity and carbon-dioxide.

We used the following photosynthetic parameters: *assimilation* as the measure of carbondioxide fixation, *transpiration* as the measure of water loss and *photosynthetic water use efficiency* as the ratio of carbon-dioxide input to water output. All of these parameters depend on stomatal regulation and the abiotic environment. In this section capacities and threshold limits of Szarvasi-1 energy grass gas exchange performance will be presented for a better knowledge of its abiotic environmental requirements (Fig. 10.). To define and to compare gas exchange capacities, growing pots were installed using three soil types (sandy soil, Alfisol-Mollisol, Aquic Mollisol) in the Botanic Garden of the University of Pécs with permanent irrigation. In addition, field experiments were established on three soil types (Alfisol, Alfisol-Mollisol, Aquic Mollisol) in South

Tall Wheatgrass Cultivar Szarvasi–1 (*Elymus elongatus* subsp. *ponticus* cv. Szarvasi–1)

This is presumably due to insufficient water and nutrient availability.

beneficial as an energy crop in mesic habitats with lighter soils.

**4. Propagation** 

generations.

**5. Crop management and production** 

as a Potential Energy Crop for Semi-Arid Lands of Eastern Europe 281

The assimilation and its capacity as the highest net photosynthetic rate in cultivated and natural C3 grasses vary greatly from slight to medium values (20-40 μmol m-2 sec-1) and in the case of C4 crops from medium to high (30-70 μmol m-2 sec-1) values under natural carbon-dioxide conditions, saturated light intensity, optimal temperature and adequate water supply (Larcher, 2003). Comparing Szarvasi-1 energy grass to other grasses or crop species, it has a low-medium assimilation capacity among C3 species with a range of 10.3 - 19.2 μmol m-2 sec-1 in greenhouse, and 10.6 – 20.3 μmol m-2 sec-1 under field conditions. Optimal water use efficiency was measured under moderate light intensity (500-1100 μmol m-2 sec-1) on all of the studied soil types under greenhouse conditions, while the maximum value was observed on sandy soil in spring (3.73 μmol/mmol). Time and phase shifting in plant growth, poor seasonal rates of assimilation and low water use efficiency detected on Aquic Mollisol under both irrigated and climatic drought conditions underline the negative effect of high clay content of soils on the optimal biomass production of energy grass crops.

Under non-stressed environmental conditions, optimum gas exchange in Szarvasi-1 energy grass occurred at the beginning of development in early or late spring, depending on irrigation and soil type. Climatic drought has a strong effect on gas exchange performance through the regulation of stomatal conductance, both for carbon-dioxide and water vapour. According to the studied ecophysiological parameters, Szarvasi-1 energy grass could be

Szarvasi-1 energy grass is propagated by seed. Since *E. elongatus* ssp. *ponticus* has evolved in regions of Europe that have long and severe winters, it germinates relatively late in the spring and by the time it develops its tussocks it is mid summer. This is why the suggested sowing time is in autumn, in the middle of September. Its germination needs no special circumstances. A period of only 7 consecutive days with approx. 16 hours dark each day and 18-20 °C air temperatures can maximize the germination success, up to 90 %. In different conditions the proportion of germinating seeds can vary between 52 and 90 %. Seedlings die rapidly without proper humidity conditions, but too much watering or a high water table are also poorly tolerated by Szarvasi-1 energy grass seedlings and juveniles. Similarly, strong competition of weeds can dramatically reduce seedling survival. The plant gets in full flower by the middle of June. The energy grass seeds belong to the transient seed bank-type, where the longevity of the seeds is shorter than a year. Hence, the seed bank of Szarvasi-1 energy grass fields contains seeds with the same age with no overlapping

The recommended sowing time is between the 1st and 20th of September. The soil must be prepared similarly to any other cereals (e.g. wheat, barley etc). The seeds should be sown at the depth of 2-2.5 cm with the sowing distance of 12-15 cm. The seed quantity for a hectare land is approx. 40 kg. The seedlings emerge in 14-18 days. Weed management is necessary in this phase of the development of energy grass plantations to avoid the weed species strengthening at the expense of energy grass individuals. In the early spring rolling on the plantation can be important to mitigate the negative effects of winter frost on the root

Hungary, under natural climatic conditions without any irrigation or fertilization. To evaluate threshold values of gas exchange parameters under different environmental regime, steady state and instantaneous field measurements by IRGA methods were executed.

Among investigated abiotic environmental parameters photon flux density and air humidity turned out to have an essential role in gas exchange performance and regulation (Salamon-Albert & Molnár, 2009, 2010). Under non-stressed soil water conditions (P2, P3, P5) carbon fixation was the most favourable at the beginning of the growing period described by the assimilation capacity and light efficiency regulated by the air humidity (Fig. 10.A). After seasonal precipitation deficiency in late summer (P4), causing a decline in soil water content, hard reduction was detected in water use efficiency because of strong decrease in assimilation capacity and light efficiency, retaining a regular level of transpiration (Fig. 10.B,C). Effect of climatic air drought was significant for stomatal conductance, going shattered in seasonal response by a greater effectiveness to transpiration (Fig. 10.D). As for the other experimental soil types, overall and seasonal assimilation capacity and light efficiency was a little bit lower on Alfisol-Mollisol and significantly depressed on Aquic Mollisol.

Fig. 10. A) assimilation, B) transpiration, C) photosynthetic water use efficiency as a function of light and D) stomatal conductance for water vapour as a function of air humidity, derived from field measurement (instantaneous data, alfisol, unpublished). Fitted curves p<0.01, P2- P5 the vegetative phenophases.

The assimilation and its capacity as the highest net photosynthetic rate in cultivated and natural C3 grasses vary greatly from slight to medium values (20-40 μmol m-2 sec-1) and in the case of C4 crops from medium to high (30-70 μmol m-2 sec-1) values under natural carbon-dioxide conditions, saturated light intensity, optimal temperature and adequate water supply (Larcher, 2003). Comparing Szarvasi-1 energy grass to other grasses or crop species, it has a low-medium assimilation capacity among C3 species with a range of 10.3 - 19.2 μmol m-2 sec-1 in greenhouse, and 10.6 – 20.3 μmol m-2 sec-1 under field conditions. Optimal water use efficiency was measured under moderate light intensity (500-1100 μmol m-2 sec-1) on all of the studied soil types under greenhouse conditions, while the maximum value was observed on sandy soil in spring (3.73 μmol/mmol). Time and phase shifting in plant growth, poor seasonal rates of assimilation and low water use efficiency detected on Aquic Mollisol under both irrigated and climatic drought conditions underline the negative effect of high clay content of soils on the optimal biomass production of energy grass crops. This is presumably due to insufficient water and nutrient availability.

Under non-stressed environmental conditions, optimum gas exchange in Szarvasi-1 energy grass occurred at the beginning of development in early or late spring, depending on irrigation and soil type. Climatic drought has a strong effect on gas exchange performance through the regulation of stomatal conductance, both for carbon-dioxide and water vapour. According to the studied ecophysiological parameters, Szarvasi-1 energy grass could be beneficial as an energy crop in mesic habitats with lighter soils.
