Gross Composition of Plants by jemimah guce

Abstract The methods commonly used in determining the moisture, dry matter, organic matter and ash contents of plant tissue samples was familiarized and the composition of the plant sample was also determined. It was done by weighing the fresh weight(62.3g, whole plant), heating in an oven, weighing again to get the dry weight(16.4g, whole plant), combusting or ashing and the last weighing to get the ash weight(5.3g, whole plant). The weights were used in calculating the other composition of the plant sample. Thus, there are proper and common methods used to determine gross composition of plants through separated processes that eliminates specific component each. Introduction Generally, plants are composed of water, organic and inorganic compounds. Water is the principal component of plants which is important for growth and development. It comprises 70 to 90 percent of plant’s total weight. Soil is the water source for terrestrial plants. It is an abundant source of water even some appears dry. Water and nutrients are being absorbed through root hairs and transported by the xylem and phloem. It is also important to maintain the turgidity of cell. For plants to develop all necessary elements must be available. These are the organic compounds that occur naturally which when any of these was excluded or depleted would cause death of organism: Carbon, Hydrogen, Oxygen and Nitrogen. Inorganic components are those absorbed by the plants directly from the surrounding which is necessary to be elaborated into

organic compounds by the plant before they can be assimilated by the body. The changing of inorganic matter into organic matter takes place principally in the green leaves of the plant by means of photosynthesis. A plant’s composition depends on the kind of environment. When measuring actual amount of plant matter, the dry weight is considered instead of the fresh because it excludes water, nutrients and other compounds the plant holds. Combusting through controlled temperature to reduce the material to a grayish white carbon-free ash. During combustion, soil OM undergoes a series of physical and chemical transformations (Chandler and others 1983).

A study was done in the Biology laboratory of SLSU, July 26, 2015. It was done to be familiar with the methods commonly used in determining the moisture, dry matter, organic matter and ash contents of plant tissue samples.

Materials and Methodology A. Preparation of Plant Materials. Freshly harvested Synedrella nodiflora was used. Dead, damaged leaves and adhering soil particles was removed by washing them off with water. After it was cleaned, it was dried using cle an tissue papers. Plant organs was separated (leaves, stems, roots), and was cut into 1 cm portions. Each portions was weighed using triple beam balance then carefully wrapped in three clean papers and labelled according to what is wrapped

within. All of these was put in the oven at 70dC for 72 hours. After 72 hours, it was cooled and weighed. B. Combustion/ Dry Ashing The plants cooled after being heated in an oven was placed separately in a weighed evaporating dish and the other with porcelain crucible. The dish was weighed using triple beam balance alone then the plant sample was put and then weighed again. Using low flame of alcohol lamp initially, the plant samples was combusted in a porcelain crucible elevated by a tripod and then the flame was gradually increased to avoid splattering of the material. Using a clean glass rod, the charred samples was carefully stirred. After it was already combusted but there are still ash remains, it was again cooled and weighed with crucible and dish. Then the ash weight was determined by getting the difference between the weight of the crucible plus ash and the tared weight of the crucible/dish. The organic matter weight on the other hand was determined by getting the difference between the dry weight and the ash weight. C. Formulas

1. water =

2. dry matter=

Fresh weight ( FW )−Dry weight ( DW ) x 100 FW

DW x 100 FW

3. ash=

Ash weight ( AW ) x 100 FW

4. organic matter=

DW −AW x 100 FW

Discussion

Figure 1. Formulas used in computing for the % water, dry matter, ash and organic matter of the sample.

% water = ((FW - DW) / FW) * 100 % dry matter = (DW / FW) * 100 % ash weight = (AW - FW) * 100 % organic matter = ((DW - AW) / FW) * 100

Table 1. The recorded and computed percentage of water, dry matter, ash, and organic matter of

Synedrella nodiflora

Fresh weight(g) Dry weight(g) Ash weight(g) Organic matter(g) %water %dry matter %organic matter %ash

LEAVES 17.3 3.9 1.7 2.20 77.5 22.5 12.7 9.8

stems 32.5 9.3 2.5 6.80 71.4 28.6 20.92 7.7

roots 12.5 3.2 1.1 2.1 74.4 25.6 16.8 8.8

total 62.3 16.4 5.3 11.1 ---------

Having a total of 62.3 g of the whole plant (17.3 g leaves, 32.5 g stems, 12.5 g roots) which is considered the fresh weight. The fresh weight still contains all the components of a living plant.

Note that the greatest amount was from the stems because of the plant sample we used are somewhat tall. After heating in an oven, the weight decreased. The weight that was lost is the amount of water leaving the dry weight (22.5% or 3.9g leaves, 28.6% or 9.3g stems and 25.6% or 3.2g roots). The dry weight composes of the organic and inorganic compounds. Because of the heating, the water component of the plant evaporated removing all the water component of the plant sample. It can be observed that when water was eliminated, there was a drastic change in their weight. Water in plants like in humans composes 70% in its body. Stems gave the greatest amount of dry weight. The stem, if broken down into their chemical component parts, are roughly made up of organic compounds such as carbohydrates, lipids, nucleic acids, and proteins. Stem has the highest organic matter compared to the leaves and roots (Feliciano, Christian Andrew., Javate, Patrick Simon. Et.al).

Whereas the ash matter of the plant is the inorganic compounds after the organic matter have been removed from the dry weight through combustion. The most widely used methods are based on the fact that minerals are not destroyed by heating, and that they have a low volatility. So after combusting the dry matter, the weight decreased because of the volatile components leaving the inorganic compound. It is important to know the processes and be able to study the plant composition in order to know what composes the plants in our surrounding. Organic matter weight can be obtained by getting the difference of the dry weight and the ash weight since the ash weight was the amount of inorganic compounds obtained from the dry weight when the organic compounds was combusted.

Table 2. The recorded and computed percentage of the whole plant of Synedrella nodiflora. % water of the whole plant 73.7 % dry matter of the whole plant 26.3 % organic matter of the whole plant 17.8 % ash of the whole plant 8.5 The percentage of water, dry matter, organic matter and ash of the whole plant was obtained using the total weight of the fresh whole plant, dry matter, ash and organic matter using the given formulas (see figure 1). The plant consist of 73.7% of water which is normal. The dry matter is the most reliable for studies of the components of plants because of the variability of the amount of water for different kinds of plants. The least amount was the inorganic matter or the ash weight which are obtained from the organic compounds from the environment that only undergone biochemical processes.

Sample calculations:

Summary and conclusion The methods commonly used in determining the moisture, dry matter and ash contents of plant tissue samples was determined and familiarized. Using the plant Synedrella nodiflora freshly uprooted and cleaned. It is first weighed to determine the fresh weight of each separated parts (leaves, stems and roots). Each part was put in a clean paper and dried in an oven for 72 hours with 70 ‘C temperature. It was then weighed to get the dry weight and the amount of water gone. The third method was the combustion, where

the dry matters were separately put in gradually increasing flame until ash was obtained. These ashes were weighed separately also. Then the datas obtained were used in calculating the other needed informations to be knowledgeable on what the plant sample contains. The most reliable basis for study would be the dry weight. The plant consist of the photosynthetic leaves which gives the plant its food. Also the roots that absorbs water and nutrients from the soil. The organic compounds are also from the soil, so the organic components of the plant will differ according to the kind of its habitat. Stem has xylem and phloem that transports those food and water to other parts of the plant like leaves. Therefore, the methods used was a help to determine how plants survive and the components of them. Results showed that the greatest component of plants was water which composes 73.7% of the fresh weight of plant. Then followed by the amount of organic matter (17.8%) and the least was inorganic matter (8.5%) of the whole plant.

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How-to Hydroponics By Keith Robertohttps://books.google.com.ph/books? id=e5xLkJLTMygC&pg=PA27&lpg=PA27&dq=organic+composition+of+plants&source=bl&ots=K5_hHkMaJ7&sig=fbxEtScxkGMAO7OP9I8MN8cDNc&hl=en&sa=X&ved=0CE4Q6AEwCGoVChMIpPLB4ruOxwIVo9mmCh097wQn#v=onepa ge&q=organic%20composition%20of%20plants&f=false

Experiment 3: Percent Composition in Plants Anna Victorinoon 7 September 2013https://prezi.com/kznbt7onat5a/experiment-3-percentcomposition-in-plants/

Source: Boundless. “The Chemical Composition of Plants.” Boundless Biology. Boundless, 21 Jul. 2015. Retrieved 04 Aug. 2015 from https://www.boundless.com/biology/textbooks/boundlessbiology-textbook/soil-and-plant-nutrition-31/nutritional-requirements-of-plants-186/the-chemicalcomposition-of-plants-710-11934/(https://www.boundless.com/biology/textbooks/boundlessbiology-textbook/soil-and-plant-nutrition-31/nutritional-requirements-of-plants-186/the-chemicalcomposition-of-plants-710-11934/