APPROVAL SHEET

The complete report of Plant Physiology with title “Measuring the Water

Potential of Plant Tissues” created by:

Name : Rissa Megavitry

Reg. Number : 091404177

Class : ICP

Group : IV (Fourth)

After it’s checked and consulted by Assistant and Assistant Coordinator, it has

fulfilled requirement.

Makassar, May 2011

Assistant Coordinator Assistant

Muh. Nur Qadry S. Yusmar Yusuf

(081404189) (081404172)

Known as,

Lecturer of Responsibility

Drs. Ismail, M.S

19611231 198603 1 015

CHAPTER IINTRODUCTION

A. Introduction

Have we ever thought how the air and water goes into the plant’s body?

The plant entire cell was surrounded by membrane. Cell membrane cans across

by all of substances. Membrane cell functions as a gauze screen at your window

which can across by air but not for the big thing like insect or gravel indeed

mosquito. How’s the certain substance can across the cell membrane? Cells of

plant can across by water, solute food substance, oxygen and carbon dioxide

either goes in or out.

Plant cell need oxygen and carbon dioxide, and how’s that substance

moves through the cell membrane? The composer of substance at this nature is

always moves. The smallest composer called particle. That particle be spread

evenly to all direction. The substances move from the high concentration to the

lower concentration of place. The moves of those substances called diffusion.

Diffusion will stop if the concentration of both places is balance.

Osmosis also occurs at the cell in this nature. The alteration of cell’s form

happens if different solution existing. Cell in the isotonic solution the volume

will constant. In this matter, the cell will get and looses the same volume of

water. Many the sea animals, such as sea star (Echinodermata) and crab

(Arthropod) the cell fluid is isotonic with its environment. If cell in the hypotonic

solution, so that cell will get much water and can cause lysis (in the animal cell),

or high turgidity (in the plant cell). On the contrary if cell in hypertonic solution,

so cell will looses many molecules of water, so cell become wrinkled and can

cause death.

In this practicum we will observe the water potential to know the

movement of water in the plant which leftover or deficiency of fluid. We will

observe the water movement in potatoes and sucrose solution. From this

practicum we will know which one that has the higher water potential. But we

also must watch the other factor that can caused deviation of observation result.

According on that mater so the practicum Plant Physiology implements.

B. Purpose

To measures the value of water potential from potato tissue.

C. Benefit

The students know how to measure the water potential of potato tissue

CHAPTER IIPREVIEW OF LITERATURE

Plant cell has the different characteristic from the animal cell, especially for

the cell wall in plant. Cell wall in high plant is the matrix which inside of it there’s

skeleton that cellulose compound as micro fibril or smooth thread. This matrix

compose from some compounds that hemicelluloses, pectin, biologic plastic, protein

and fat. Generally, the cell wall distinguish become primary cell wall and secondary

cell wall. The difference of both cell walls based on the flexibility, thickness;

compose of micro fibril and its growth. All the activity of plant cell depends on the

existence of cell wall. Cell wall also functions as the way of water exchange, foods

and mineral salt to the cell (Anonymous a, 2011).

According to Anonymous b (2011), water is the 89-95% of plant weight

which lives in the water. Inside of cell, water needed as the solvent of nutrition,

besides that water also as the substrate or reactant for the various biochemical

reactions, and also the cause of enzyme formation. Plant which experiences water

deficiency will wilt even dead. There’re five main mechanisms which move the water

from one place to the other place, that through: diffusion, osmosis, capillary pressure,

hydrostatic pressure, and gravitation.

a. Diffusion

Diffusion is the molecule movement or ion from the high concentration to the

lower concentration. The rate of diffusion depends on temperature and density of

medium. Diffusion of gas is faster than the liquid substance, meanwhile the

diffusion of compact substance slower than the liquid. The movement of big

molecule is slower than the little molecule.

b. Osmosis

Osmosis is diffusion through the semi permeable membrane. Those molecules

will diffuse from the high concentration to the lower concentration. The osmosis

process will stop if the concentration of substance in the both place is balance.

Osmosis preventable with pressure, that’s why the physiologist always use

osmotic potential term that the pressure which needed to prevent osmosis.

c. Capillary pressure

If capillary pipe immersed to the water, so the water surface in the capillary pipe

will go up until experience the equal between the strains which pull that water

with the height. The pressure which pulls the water called capillary pressure.

Capillary pressure depends on the diameter of capillary: more little the capillary

so the pressure is bigger which pull that water column

d. Hydrostatic pressure

Hydrostatic pressure in the cell also called turgor pressure. The turgor pressure is

important for the cell because can make the cell and tissue become rigid. The

water potential of a plant cell essentially is the combination between osmotic

potential with its pressure potential.

e. Gravitation

Water moves also to respect the earth gravitation, so need the pressure to pull the

water. In herb, the gravitation influence can be ignoring because the different of

elevated in that part of plant is relatively small. In high plant, the influence of

gravitation is very real.

Water potential is the capability of water to moves. Water moves from the

solution with high water potential to the solution with lower potential (water potential

can measure with pressure unit). Pure water (100% water) has Ψw = 0 (zero), as the

highest water potential. All of the solutions have Ψw < 0. If the diffusion of solute

particle is more definite than solvent, will cause the gradient of water potential. If the

pure water in the one side of membrane and solution in the other side (especially in

osmometer), so the water potential of solution is lower than the water potential of

pure water. According the treaty, water potential of water in the atmosphere pressure

and the same temperature with that solution is equal with “0”, so water potential of

water in the atmosphere pressure will be in negative valuable. Therefore, the water

molecule will diffuse from the high potential to the lower potential. As the height of

pressure will increase the water potential, so water potential in osmotic system will

increase to 0 (Ismail, 2008).

Osmotic potential is the potential which caused by the solute substance. The

sign is always negative. Pressure potential is the potential which caused by

hydrostatic pressure of cell contain to cell wall. The value is positive, zero or can also

negative. Adding of pressure (formation turgor pressure) caused the pressure potential

become more positive. Matrix potential caused by water bond in protoplasm colloid

and surface (cell wall). Matrix potential is negative sign, but in generally the cell

which has vacuole, its value can be ignoring (Ismail, 2011).

Plant cell can loss water, if the water potential at outside of cell is lower than

the water potential inside of cell. If the cell loss water in big volume, so is possible

the volume of cell’s content will decrease dramatically so can’t fill all the room

which formed by cell wall. It means, the membrane and cytoplasm will getting loose

from cell wall, it called plasmolysis process. The cell which had plasmolysis

recoverable with entered it to the pure water (Anonymous a, 2011).

CHAPTER IIIOBSERVATION METHOD

A. Date and Time

Day/Date : Wednesday/May, 4th 2011

Time : 07.30 – 09.10 am WITA

Place : Laboratory Biology FMIPA at 2nd floor, east side

B. Tools and Materials

1. Tools

a. Razor blade

b. Analytic weights

c. 12 pieces of petri dish

d. Cork drill with 0.6-0.8 cm diameter

2. Materials

a. Plant material: Solanum tuberosum (potato)

b. Chemical materials: Aquades, and sucrose solution: 0.1 M, 0.2 M, 0.3 M,

0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M

C. Work Procedures

1. Prepared 12 petri dishes and filled with 100 ml of solution: aquades, sucrose

solution 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M

2. Made 12 cylinder of potato with 4 cm long. Removed the skin. Then cut into

small part used razor blade.

3. Washed the sliced potato by water the dried in filter paper then weighed. Next

entered to the sucrose solution. Did it in every potato cylinder. Entered the

sliced potato in same time to sucrose solution.

4. After 10 minutes, put outside that potato slices then dried used filter paper and

weighed again. Did it to all sample of observation.

5. Calculated the weigh exchange of potato used the formula below:

% weight alteration= end weight – initial weightinitial weight

×100 %

6. Then made the graphic and plotted the percentage of weight in ordinate and

concentration of sucrose solution in abscissa.

7. Calculated the osmotic potential (Ψs) for each concentration of sucrose

solution, to determinate the water potential of tissue by used formula below:

Ψs = -miRT

Whereas, Ψs : osmotic potential

m : molarities of solution

i : ionisation constanta (sucrose = 1)

R : gas constanta (0.00831 bar/molo)

T : absolute temperature (oC + 273)

8. Determinated with interpolated from the graphic, concentration of sucrose

which not caused the alteration of weight. And calculated the Ψs from this

solution. The value of Ψs is comparable with water potential (Ψw) of tissue.

CHAPTER IVOBSERVATION RESULT AND DISCUSSION

A. Observation Result

Table of relationship between concentrations with weight alteration of potato

SOLUTONINITIAL

WEIGHT (g)

END WEIGHT

(g)

ALTERATION

OF WEIGHT (g)

PERSENTAGE

OF WEIGHT

ALTERATION

(%)

AQUADES 0.7 0.6 0.1 14.28%

0.1 0.7 0.6 0.1 14.28%

0.2 0.6 0.4 0.2 33.33%

0.3 0.6 0.4 0.2 33.33%

0.4 0.9 0.7 0.2 22.22%

0.5 0.7 0.5 0.2 28.57%

0.6 0.7 0.5 0.2 28.57%

0.7 0.8 0.5 0.3 3.57%

0.8 0.6 0.6 0 0%

0.9 0.6 0.4 0.2 33.33%

B. Analysis of Data

Formula:

% weight alteration= end weight – initial weightinitial weight

×100 %

1. Aquades

% weight alteration=0.6 – 0.70.7

×100 %=14.28 %

2. Sucrose 0.1 M

% weight alteration=0.6 – 0.70.7

×100 %=14.28 %

3. Sucrose 0.2 M

% weight alteration=0.4−0.60.6

×100 %=33.33 %

4. Sucrose 0.3 M

% weight alteration=0.4−0.60.6

×100 %=33.33 %

5. Sucrose 0.4 M

% weight alteration=0.7−0.90.9

× 100 %=22.22 %

6. Sucrose 0.5 M

% weight alteration=0.5−0.70.7

× 100 %=28.57 %

7. Sucrose 0.6 M

% weight alteration=0.5−0,70.7

× 100 %=28.57 %

8. Sucrose 0.7 M

% weight alteration=0.5−0.80.8

×100 %=37.5%

9. Sucrose 0.8 M

% weight alteration=0.6−0.60.6

× 100 %=0 %

10. Sucrose 0.9 M

% weight alteration=0.4−0.60.6

×100 %=33.33 %

Formula to calculate the osmotic potential is:

Ψs = -miRT

Whereas, Ψs : osmotic potential

m : molalities of solution

i : ionisation

R : gas constanta

T : absolute temperature

1. Aquades

Ψs = -miRT

= - 0 x 1 x 0.00831 x 298

= 0 bar

2. Sucrose 0.1 M

Ψs = -miRT

= - 0.1 x 1 x 0.00831 x 298

= - 0.248 bar

3. Sucrose 0.2 M

Ψs = -miRT

= - 0.2 x 1 x 0.00831 x 298

= - 0.495 bar

4. Sucrose 0.3 M

Ψs = -miRT

= - 0.3 x 1 x 0.00831 x 298

= - 0.743 bar

5. Sucrose 0.4 M

Ψs = -miRT

= - 0.4 x 1 x 0.00831 x 298

= - 0.991 bar

6. Sucrose 0.5 M

Ψs = -miRT

= - 0.5 x 1 x 0.00831 x 298

= - 1.238 bar

7. Sucrose 0.6 M

Ψs = -miRT

= - 0.6 x 1 x 0.00831 x 298

= - 1.486 bar

8. Sucrose 0.7 M

Ψs = -miRT

= - 0.7 x 1 x 0.00831 x 298

= - 0.733 bar

9. Sucrose 0.8 M

Ψs = -miRT

= - 0.8 x 1 x 0.00831 x 298

= - 1.981 bar

10. Sucrose 0.9 M

Ψs = -miRT

= - 0.1 x 1 x 0.00831 x 298

= - 0.248 bar

C. Discussion

Observation of water potential in plant tissue did by used potato cylinders

which were soaked in different concentration of sucrose solution and in aquades

for 10 minutes. The concentration of sucrose solution is different in order to

know the influence of concentration with osmosis process. Meanwhile the

aquades here is as a control. From the observation explained that the water

potential in aquades and sucrose solution is lower than water potential of potato

cylinder, so we can conclude that liquid from potato cylinder flow out to the

environment.

The table shown that alteration value from aquades until sucrose 0.9 M

solution is change and negative except for sucrose 0.8 M solution which shown

nothing alteration of weight. This because the initial weight of potato is bigger

than the end weight, as the result of weight reduction because the water goes out

from cell to sucrose solution. The other factor that can influence in negative

weight alteration is inequality of cylinder thickness, the duration of soaking, and

also drying process which not good so the potato which should weighing in dry

condition still contains water.

Water movement from potato to sucrose solution shown that

concentration of potato higher than the outside of cell (sucrose solution), so this

solution is hypertonic solution (the solute level is higher than its surrounding). In

this observation potato in sucrose 0.1 M – 0.7 M solution experience the

alteration of weight and also in sucrose 0.9 M solution because the gradient of

solution in outside of cell is different with at inside of cell which called isotonic

solution. So the result of this observation is appropriate with the theory that water

moves from the high potential to the lower potential, this process called osmosis.

CHAPTER VCONCLUSION AND SUGGESTION

A. Conclusion

Water potential is the capability of water to moves. Water moves from the

solution with high water potential to the solution with lower potential (water

potential can measure with pressure unit). Pure water (100% water) has Ψw = 0

(zero), as the highest water potential. Water potential of a solution is influential

to liquid movement in the plant tissue. Bigger the water potential so the

capability of liquid to osmosis is bigger too. The different from observation result

with theory caused by the mistakes which happen when observation, such as

drying process of cylinder potato using filter paper, difference thickness of potato

cylinder caused difference the membrane thickness, and also duration of soaked.

B. Suggestion

1. Assistant must be on time when attend in practicum and must lead the

apprentice when the practicum goes on.

2. The tools in the laboratory must be complete in order the practicum can goes

on good.

3. Apprentice must be on time and more carefully when does observation.

BIBILIOGRAPHY

Anonymous a. 2011. Fisiologi Tumbuhan Potensial Osmosis. iqbalali.com. Accessed on 16th May 2011

Anonymous b. 2011. Air Dalam Tumbuhan. klimatologi.wordpress.com. Accessed on 16th May 2011

Ismail. 2008. Fisiologi Tumbuhan. Jurusan Biologi FMIPA UNM: Makassar

Ismail. 2011. Penuntun Praktikum Fisiologi Tumbuhan. Jurusan Biologi FMIPA UNM: Makassar

Anonymous a

Sel tumbuhan memiliki ciri fisiologi yang berbeda dengan sel hewan khususnya

dengan keberadaan dinding sel pada sel tumbuhan. Dinding sel pada tumbuhan tinggi

merupakan matriks yang di dalamnya terdapat rangka, yaitu senyawa selulosa yang

berwujud mikrofibril atau benang halus. Matriks pada dinding sel ini tersusun dari

beberapa senyawa yaitu hemiselulosa, pektin, plastik biologik, protein dan lemak.

Dinding sel secara umum dibedakan menjadi dinding sel primer dan dinding sel

sekunder. Perbedaan antara kedua macam dinding ini terletak pada fleksibilitas,

ketebalan, susunan mikrofibril dan pertumbuhannya. Seluruh aktivitas sel tumbuhan

sangat tergantung dengan keberadaan dinding sel ini. Dinding sel selain berfungsi

untuk proteksi isi sel juga berperan sebagai jalan keluar masuknya air, makanan dan

garam-garam mineral ke dalam sel.

Anonymous b

Air merupakan 85 – 95 % berat tumbuhan herba yang hidup di air. Dalam sel, air

diperlukan sebagai pelarut unsur hara sehingga dapat digunakan untuk

mengangkutnya; selain itu air diperlukan juga sebagai substrat atau reaktan untuk

berbagai reaksi biokimia misalnya proses fotosintesis; dan air dapat menyebabkan

terbentuknya enzim dalam tiga dimensi sehingga dapat digunakan untuk aktivitas

katalisnya. Tanaman yang kekurangan air akan menjadi layu, dan apabila tidak

diberikan air secepatnya akan terjadi layu permanen yang dapat menyebabkan

kematian. Terdapat lima mekanisme utama yang menggerakkan air dari suatu tempat

ke tempat lain, yaitu melalui proses: difusi, osmosis, tekanan kapiler, tekanan

hidrostatik, dan gravitasi.

a. Difusi

Difusi adalah pergerakan molekul atau ion dari dengan daerah konsentrasi tinggi ke

daerah dengan konsentrasi rendah. Laju difusi antara lain tergantung pada suhu dan

densitas (kepadatan) medium. Gas berdifusi lebih cepat dibandingkan dengan zat cair,

sedangkan zat padat berdifusi lebih lambat dibandingkan dengan zat cair. Molekul

berukuran besar lebih lambat pergerakannya dibanding dengan molekul yang lebih

kecil.

b. Osmosis

Osmosis adalah difusi melalui membran semipermeabel. Molekul-molekul tersebut

akan berdifusi dari daerah dengan konsentrasi tinggi ke konsentrasi rendah. Proses

Osmosis akan berhenti jika konsentrasi zat di kedua sisi membran tersebut telah

mencapai keseimbangan.Osmosis dapat dicegah dengan menggunakan tekanan. Oleh

karena itu, ahli fisiologi tanaman lebih suka menggunakan istilah potensial osmotik

yakni tekanan yang diperlukan untuk mencegah osmosis.

c. Tekanan kapiler

Apabila pipa kapiler dicelupkan ke dalam bak yang berisi air, maka permukaan air

dalam pip a kapiler akan naik sampai terjadi keseimbangan antara tegangan yang

menarik air tersebut dengan beratnya. Tekanan yang menarik air tersebut disebut

tekanan kapiler. Tekanan kapiler tergantung pada diameter kapiler : semakin kecil

diameter kapiler semakin besar tegangan yang menarik kolom air tersebut

d. Tekanan hidrostatik

Tekanan hidrostatik dalam sel disebut tekanan turgor. Tekanan turgor yang

berkembang melawan dinding sebagai hasil masuknya air ke dalam vakuola sel

disebut potensial tekanan. Tekanan turgor penting bagi sel karena dapat menyebabkan

sel dan jaringan yang disusunnya menjadi kaku. Potensial air suatu sel tumbuhan

secara esensial merupakan kombinasi potensial osmotic dengan potensial tekanannya.

e. Gravitasi

Air juga bergerak untuk merespon gaya gravitasi bumi, sehingga perlu tekanan untuk

menarik air ke atas. Pada tumbuhan herba, pengaruh gravitasi dapat diabaikan karena

perbedaan ketinggian pada bagian tanaman tersebut relatif kecil. Pada tumbuhan yang

tinggi, pengaruh gravitasi ini sangat nyata.