Introduction
Background
Invasive plant species can be described as “introduced species that have the ability to thrive in areas beyond their natural range and dispersal” (Cellot et al. 1998). This category of plants easily adapts to new environments in an aggressive manner with high reproduction rates. They lack natural enemies, this combined with their quick multiplication results into outbreak populations in most areas where they are found (Luneva 2009).
Research evidence strongly shows a relationship between the persistence of invasive plant species and the loss of native species with disturbance and fluctuations in soil fertility (DiTomaso 2007). The addition of Nitrogen (N) to soil in disturbed grazing land has been shown to increase the abundance of invasive species such as cheat grass and the “European forget me not” (Myosotis scorpioides), while reduction in N availability has been shown to relatively increase the abundance of the native perennial species. A study carried out by Young in 1998, showed that the seedling establishment of the medusahead increased with fertilization by NO3– , and was not affected by NH4+ fertilization and decreased with the immobilization of the mineral N (Thomas et al. 2003).
The absorption of Nitrate is thought to relatively vary with the type of soil in use due to the difference in water holding capacity. Documented evidence indicates that the waterlogging properties of the clay soil promote denitrification and the loss of nitrogen (Ling 2010). However, other types of soils such as the sandy loam have a higher percentage of nutrient losses through leaching (Cellot et al. 1998).
In the current study different types of soil (sandy loam clay loam and silt loam) will be used to study the relative uptake of nitrogen that will be measured by the germination and growth of Myosotis scorpioides.
The varying types of soil to be used in this study include: sandy loam which can be described as soil material that contains 7 to 20% clay, more than 52% sand, with the percentage of silt and percentage of sand being 30% or more; silt loam, described as soil material that has 50% or higher content of silt and between 12% and 27% clay, or 50 to 80% silt and less than 12% clay; and finally clay loam, described as soil material that contains 27 to 40% clay and 20 to 45% sand (Thomas et al. 2003).
Myosotis scorpioides is a herbaceous perennial plant that belongs to the genus Myosotis, its commony known as the “European forget me not” (Ling 2010). The plant thrives in wet places and is most commonly found near streams and rivers (Luneva 2009). Myosotis scorpioides reproduces sexually through seeds and vegetatively via stolons that root at the nodes (Thomas et al 2003). No data is available to indicate the number of seeds that each Myosotis scorpioides plant produces, however, its close relative Myosotis alpestris has been documented to produce between 20 and 120 seeds per plant (DiTomaso 2007).
The plant mostly grows in areas with disturbance suggesting that the germination of its seeds is promoted by soil disturbance. A study carried out in “Germany identified seedlings of Myosotis scorpioides scattered in moderately grazed areas suggesting that grazing disturbances promote germination” (Luneva 2009). The plant is native in the temperate areas of Europe and Asia but grows exotically in the United States, Canada and other parts of the world. Myosotis scorpioides forms beautiful plant cover and is therefore used as a garden plant (Thomas et al. 2003). Studies show that the plant tends to escape from gardens to wet areas where it forms dense monocultures (Ling 2010).
In the United States, the plant is found in 41 states and is considered invasive in several of them and has been banned in Massachusetts (Luneva 2009).
The goal of this study is to evaluate the influence of Nitrate concentrations on the growth and germination of Myosotis scorpioides seeds planted in either sandy loam, silt loam or clay loam. As described earlier, the relative germination of Myosotis scorpioides seeds increases with increased soil disturbance, mainly in the grazing areas.
The study hypothesizes that the increase in nitrate availability will increase the percentage of germination and the rate of growth of Myosotis scorpioides. Additionally, the study hypothesizes that change in the type of soil (Sandy loam, silt loam, and clay loam) does not affect germination but may cause variation in the rates of growth (DiTomaso 2007).
Problem Statement
Non perennial invasive plant species have tended to relatively increase in number following soil disturbance by activities such as grazing. Such an increase has led to noxious levels of the plants endangering the perennial or native plant populations. The increased rate of germination has been linked to soil disturbance that increases the level of nitrogen (N) availability. Studies have linked but not confirmed the increase in N availability to increased rates of germination of invasive plants. Studies show that the amount of N availability and rate of release for plant growth depends on soil type. Thus this study will seek to identify the correlation between nitrogen, germination and growth of Mysotosis scorpioides, and soil type.
Objectives
The study seeks to investigate the following specific objectives:
- The effect of increasing nitrite concentration on the germination and growth of Mysotosis scorpioides
- THe effect of soil variation in the uptake of nitrogen for the germination and growth of Mysotosis scopioides
Methods
- The materials (seeds of M. Scorpiodes, soil samples and planting trays) o be used in this study will be commercially obtained.
- The different commercially obtained soil samples (sandy loam, clay loam, and silt loam) will divided into three parts each and treated with varying concentrations of nitrate (0mg/L, 5mg/L, and 10mg/L) which will then be placed in separate propagation trays without drainage holes.
- The seeds of the M. Scorpioides will then be planted in the different trays containing different soil samples (sandy loam, clay loam and silt loam) and nitrates at different concentrations.
- Three seeds will be planted in each propagation tray to maximize the likelihood of germination.
- After planting, the propagation trays will be placed in a safe greenhouse where they will be watered and observed daily for seed germination.
- The number of germinated seeds per tray will be determined and then related to the concentration of nitrate and the soil sample used
- After germination, the height of the plants will be measured twice a week (Mondays and Fridays) for two weeks and the data will be recorded according to the soil sample and concentration of nitrate.
- This data will then be used to determine the effects of varying concentrations of Nitrogen on the germination and growth of S. Scorpioides in different soil substrates.
References
Cellot, B., F. Mouillot, and C. Henry. 1998. Flood Drift and propagule bank of aquatic macrophytes in the riverine wetland. Journal of vegetation Science. 9(5). 631-640.
DiTomaso, J., and E. Healy. 2007. Weeds of California and other Western States.
University of California Agriculture and Natural Resources Communication Services, Oakland, CA. 834 p.
Ling, C. 2010. Myosotis scorpioides. USGS Nomindigeneous Aquatic Species Database, Gainesville, FL. Web.
Luneva, N. 2009. Weeds, Myosotis arvensis L. – Common (field) Forget-me –not.
AgroAtlas. Interactive agricultural ecological atlas of Russia and neighboring countries: Economic plants and their diseases, pests, and weeds. 2012. Web.
Thomas A., T. Charles, and A Douglas. 2003. Nitrogen effects on seed germination and seedling growth. J Range Manage. 56: 646-654 p.