Brassica rapa, more commonly known as field mustard is part of the taxonomic group Family Brassicaceae. According to the Wisconsin Fast Plants Program, B. rapa is a rapidly-cycling species or a fast plant. This plant was believed to have originated from the highlands near the Mediterranean Sea (Tsunoda, 1980 as cite by Rakow, 2004). Nishi (1980, as cited by Rakow, 2004) reported that this species rapidly grows under low temperature conditions. According to Warwick and Francis (1994), B. rapa extensively grows to coastal lowlands, plateaus, hills and montane regions having an elevation of up to 2300 meter above sea level. Typically, the range of B. rapa extends to coastal lowlands, plateaus, hills, and montane areas up to 2300 m. Thus, B. rapa is widely distributed to the Scandinavian regions, spreading across western and eastern Europe and Germany. The species was introduced as an agricultural species in China through western Asia or Mongolia and was also believed to be introduced into Japan by China or Siberia. Similarly, B. rapa was also later introduced into Canada and U.S as a weed and an agricultural species. In Canada, B. rapa is prevalent in disturbed habitats, such as in crops, fields, gardens, roadsides and waste places as described by Warwick and Francis (1994).
Based on morphological characteristics, B. rapa was further categorized into three distinct groups. Those commonly found in the Canadian and Polish regions were the oil-type rape, or summer turnip rape which canola is a specific form. The leafy-type encompasses the “chinensis group (pak-choi, celery mustard), the pekinensis group (Chinese cabbage), and the perviridis group (tendergreen)” while the rapiferous-type comprises the “rapifera group (turnip, rapini), and the ruvo group (turnip broccoli, Italian turnip)” as reported by Hortus Third (1976) and Prakash and Hinata (1980). The oil-type rape and vegetable types are an essential source of diet not only for humans but for sheep and cattle. In India, Sweden, Finland, and Canada, the species is propagated as an oilseed crop (Nishi, 1980 as cited by Rakow, 2004).
Literatures on B. rapa are indeed fast accumulating. Numerous studies from the genetic level to the ecosystems level have been undertaken to fully understand the nature of B. rapa. In this report, the researchers aim is to understand the response of B. rapa to limiting factors such as temperature, nutrient concentration and water availability. Specifically, the objective is to determine the effect of different fertilizer concentrations on the growth of B. rapa.
Cultivation of Brassica rapa
A total of 120 Brassica rapa seeds will be grown covering different type of experimental conditions. All set up will be exposed under the same temperature, moisture, and lighting conditions, while the concentration of fertilizers differs. That is, 30 seeds will be planted for the control (i.e. no fertilizers added) as a reference for comparison, and 30 seeds each will be planted for the set up with soil with 5%, 10% and 15% of nitrogen fertilizer. These seeds will be planted on used potting soil at a depth of 0.5 centimeter. Nitrogen fertilizers will be added each week except for the control after the seed germinates. The height and width of the plant will be recorded weekly. After six weeks, when the plant has fully developed, the plant will be harvested to determine the biomass.
Using SPSS or other statistical package software, data will then be subjected to analysis of variance to determine if the concentration of nitrogen fertilizers added every week has a significant effect on the height, width and biomass of Brassica rapa. Further, a regression analysis will be performed to determine how growth is related to the concentration of nitrogen fertilizers.
Hortus Third (1976). A Concise Dictionary of Plants Cultivated in the United States and Canada. Liberty Hyde Bailey Hortorium, ed. Macmillan Publishing Company, Cornell University.
Prakash, S. and K. Hinata (1980). Taxonomy, cytogenetics and origin of crop Brassicas, a review. Opera. Bot. 55: 3-57.
Rakow, G. (2004). Species Origin and Economic Importance of Brassica. Biotechnology in Agriculture and Forestry, 54: 3-11.
Warwick, S. I. and A. Francis (1994). Guide to the Wild Germplasm of Brassica and Allied Crops, Part V: Life History and Geographical Data for Wild Species in the Tribe Brassiceae (Cruciferae). Technical Bulletin 1994, Centre for Land and Biological Resources Research, Agriculture and Agri-Food Canada.