DEVELOPMENT, MORPHOLOGY, DRY MASS ACCUMULATION AND CHEMICAL COMPOSITION OF SPARTINA PECTINATA LINK. AT CONTROLLED WATER LEVEL UNDER MARSHY CONDITIONS
DOI:10.30825/5.EJPAU.182.2020.23.1

Waldemar Helios
Institute of Agroecology and Plant Production Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

Spartina pectinata Link (prairie cordgrass) is a plant that can grow in a wide range of environmental conditions. The aim of this study was to describe the development, morphological traits, dry mass accumulation and chemical composition of this plant in container cultivation under marshy conditions. The water level was at the same level as the ground surface. Based on the test results it can be concluded that Spartina pectinata can grow under wetlands and confined space conditions. However, such a research environment causes that the density of shoots per 1 m² was at the end of vegetation from 155 to 888 units, and the diameter of shoots was around 3 mm. The appearance of new shoots was observed during the entire vegetation period. Prairie cordgrass produced more and more shoots and inflorescences every year, as well as more and more underground and aboveground mass of plants. The ratio of shoots to roots and rhizomes was 1:1.48.

Key words: Prairie cordgrass, morphological traits, dry mass, macronutrients content and uptake.

INTRODUCTION

Research on the cultivation of energy crops in our climatic zone has been conducted in Poland since the end of the 1980s [17, 18]. Depending on the intended use, was selected the appropriate plant species, characterised by a specific chemical composition and yield volume. Identifying bioenergy crops that can be produced successfully on marginal lands reduces the pressure to produce energy crops on land that would otherwise be used to produce food crops [14, 29]. Abiotic-stress tolerance is an important characteristic of energy crops intended for this purpose [25, 27, 28].

Excellent stress tolerance and high biomass yields cause prairie cordgrass to become a good candidate for energy crops on marginal land [9, 15].

The genus Spartina has the most northerly distribution of any of the C4 perennial grasses [22]. Prairie cordgrass forms loose clumps of 0.90 to 2.40 m tall plants with densely attached leaves up to 0.80–0.90 m long and 3 to 13 mm wide. This grass develops a strong and deep root system of 1.5 to 3 m long, which allows the plant to endure short-term droughts. In mid-summer, the plants form 0.30 m long panicle-type inflorescences. Generative shoots are hollow [19]. It is a tall, rhizomatous, warm-season species found in Canada to 60° N latitude and throughout the continental USA, with the exceptions of Louisiana to South Carolina in the Southeast, and California, Nevada and Arizona in the West [6, 21]. It is distributed throughout the eastern coast and inland marshes [13, 20, 21]. However, Mobberley [20] frequently found prairie cordgrass in open dry prairie and on high ground along railroad rights-of-way in the Midwestern United States.

It is characterized by high adaptability to different habitats [1, 11, 12, 19]. The large carbon storage capacity of prairie cordgrass in proaxes and rhizomes makes it useful for carbon sequestration purposes [6]. Experiments conducted in Poland have shown that prairie cordgrass well tolerates unfavourable conditions in the vicinity of nitrogen plants, as well as on a reclaimed coal heap [17]. Evaluations of this plant in Europe and North America indicated it has high potential for biomass production, relative to switchgrass, in short-season areas [6]. The highest yields are obtained on sites with sufficient water supply [11]. The ability of Spartina to establish vegetatively and grow well under variable water levels leads us to recommend further testing in stormwater wetlands, to reduce weed invasions [7].

However, although Spartina pectinata is tolerant of high water tables, it can be excluded by prolonged flooding [10, 26].

 A particularly invasive species of weed, causing shallowing of the bottom of water reservoirs and drainage of wetlands is common reed. Due to less invasiveness [23] and well-developed, more compact root system than in common reeds, prairie cordgrass should be used more often to reinforce embankments, reservoir banks and watercourses.

OBJECTIVE AND SCOPE OF RESEARCH

Although prairie cordgrass is a widely spread plant, there is little scientific literature on this species and publicly available information on its development, the environmental conditions under which it can grow and yield are sometimes contradictory. Our objective was to describe morphology, shoots density and biomass production of prairie cordgrass during the first three years after planting at a constant water level equal to that of the ground surface. Moreover, the chemical composition was determined and the nutrients uptake was calculated.

MATERIALS AND METHODS

The experiment was conducted in the field of the Institute of Agroecology and Plant Production, University of Life Sciences in Wrocław (51°10'35''N, 17°07'13''E) using a complete randomization method in 3 repetitions in the years 2015–2017. Prairie cordgrass plants were taken from a nearby plantation on 20.04.2015 and were planted in 9 containers, each 0.25 m² (0.5 × 0.5 m) and 0.5 m deep, and then they were buried in the ground (Fig. 1).

The field experiments were carried on light soil defined as a very light soil, on loose sand and sandy gravel. It is visible that the soil is from slightly acidic to neutral, the content of phosphorus is from medium to high, potassium is medium and the content of Mg is from medium to high. The pH of the soil and the content of macronutrients are described in Table 1.

Four root cuttings was placed in each of the containers. The water level in the containers was maintained flush with the ground surface (±5 cm). Water with a hardness of 15°n was used for watering. The height of plants were measured 10 times and the number of shoots were measured 12 times in containers during vegetation. In each repetition, the height, diameter and weight of 10 shoots were examined after the end of the vegetation. Fresh mass of shoots, roots and rhizomes was taken from 0.25 m². Then, the underground parts of the plants were rinsed from the soil. The root losses during washing were estimated at less than 2%. Dry mass was obtained by drying for 24 hours at 50°C and then for 5 hours at 105°C.

Shoots were collected from ten randomly chosen plants to determine the chemical composition. Plant material was dried, minced and there was performed chemical analysis:

• Raw ash – was determined by burning plant material at 600°C in an electric furnace,
• The Kjeldahl method using the Kjeltec apparatus was applied for the total nitrogen determination,
• Potassium, calcium concentrations were determined by a colometric method,
• Phosphorus concentration was determined by a colometric method with vanadium and molybdenum reagents,
• Magnesium concentration was determined by a colometric method with yellow titanium.

All studied parameters were evaluated statistically, using the analysis of variance, at the confidence level of 0.05. The correlation coefficients are also significant with p<0.05. The AWA programme was used for data computation [3]. The results were prepared using Excel 2000 and Statistica 12 Pl.

RESULTS AND DISCUSSION

In the first half of the 20th century, the average annual air temperature was 8.6°C, the average temperature of the vegetation period (IV–IX) 14.7°C, and with temperatures above 15°C – 95. Frosty days is below 30. The annual average temperatures in the years of research were higher than the long-term average. The detailed temperature are described in Table 2.

The shoot density ranged from 100 tillers m² to 1140 tillers m² in natural populations [6, 8]. In our own research, the number of shoots at the end of vegetation increased from 156 in the first year after planting to 888 at the end of the research (Tab. 3).

New shoots appeared during the whole vegetation period. In the first year after planting, the formation of new erect tillers above ground level was more evenly distributed over time than in the third year, when more than 70% of new erect tillers above ground level appeared up to 12 days after the beginning of vegetation (Tab. 3, Fig. 2).

The emergence of new shoots peaked in April and all above-ground stems had died by mid-November (Fig. 5). It was similar in the research of other authors in the conditions of Eastern England [22]. A large number of erect tillers was observed under the ground level, when there was a transfer of nutrients from the aboveground shoots to the rhizome of the plant at the end of the vegetation period (Fig. 3).

A similar observation in three stands of 'Red River' was described by Boe at all [6]. Prairie cordgrass  development is illustrated in Figures 4, 5.

In the Bałuch-Małecka study [2] in 1 year of the experiment the height of plants was 0.92 m.  Majtkowski [18] found that Spartina pectinata reached the height of 2.30 m in the fourth year of growth. Boe et al. [6] showed that the number of leaves on a shoot was from 4.4 to 4.8. In own research the plants were lower and had more leaves on the stem. The uneven new shoots growth during the vegetation and therefore large differences in their height caused that despite the slight tendency to increase the height of plants and the number of leaves per plant, the differences in years were insignificant. A significant increase in plant height with the age of the plants was observed only on the 96th day after the beginning of vegetation (Tab. 4).

The similarly to the number of shoots per 1m² between the first and the third year after planting, the number of inflorescences per unit area were increased. No significant differences in the diameter of shoots were observed (Tab. 5).

Kowalczyk-Juśko [16] noticed a small prairie cordgrass yield in the first year after planting and its increase in the following years. In our own research, year after year, its dry mass of rhizomes, roots and shoots was increasing. However, the dry mass of rhizomes and roots per 1 shoot did not change significantly. The proportions of aboveground to underground parts were 1:1.48. A larger ratio of roots and rhizomes to aboveground shoots was observed (1:1.65) in the natural environment of prairie cordgrass occurrence [6]. It can therefore be concluded that under the natural conditions of this plant, the groundwater level is often below the surface of the ground and under such conditions the prairie cordgrass produces a stronger root system than in its own experience. After the end of vegetation, the dry mass of one shoot increased significantly in the first two years of the study. No significant differences in water content were observed in the aboveground and underground parts of plants. This may indicate that in all the years of the study the plants managed to finish vegetation before winter (Tab. 6).

Boe [4], Boe  and Beck [5] recorded significant positive linear correlations between the number of shoots per 1 m², dry mas per shoot and the yield of switchgrass biomass.

In our own experiment with prairie cordgrass, a positive correlation between number of shoots and dry mass of underground and aboveground parts of plants and dry mass of 1 shoot was confirmed (Tab. 7).

The shoots were characterized by a lower content of crude ash than underground parts of plants. Higher content of nitrogen, potassium and phosphorus in roots and rhizomes than in shoots indicates the efficient transfer of these elements at the end of vegetation from aboveground to underground parts of plants (Tab. 8).

Lower nitrogen content in the overground parts of prairie cordgrass than in willow [24] after the vegetation caused in relatively low amounts of nitrogen oxides were released into the atmosphere as a result of plants combustion.

High biomass yield was obtained in a pot experiment due to good lighting of plants (Tab. 6).

In the natural environment [5] and in field experiments [11] the yield of prairie cordgrass was low, in effect the accumulation of nutrients per hectare in the harvested biomass was usually lower than in Table 9 and the fertilization needs of this plant were relatively small.

CONCLUSIONS

To conclude, these results reveal that the cultivation prairie cordgrass in containers under marshy conditions is possible. However, such a research environment causes that the prairie cordgrass shoots are low and have a small diameter. However, a very large plant density resulted in a large accumulation of dry matter. Due to the marshy research environment, the ratio of roots and rhizomes to shoots was high (1:4). At a later stage of the research it is useful to check how the plant reacts to different doses of domestic sewage. Potentially, it would be a plant that could be used in domestic sewage treatment plants.

Received: 26.05.2019
Reviewed: 30.07.2019
Accepted: 31.08.2019

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